Mineral Deposits 

of Central America 

By RALPH J. ROBERTS and EARL M. IRVING 

With a section on 

MANGANESE DEPOSITS OF PANAMA 

By FRANK S. SIMONS 

GEOLOGICAL SURVEY BULLETIN 1034 

Prepared under the auspices of the 

International Cooperation Administration, U. S. Department of State 

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON a 1957 
UNITED STATES DEPARTMENT OF THE INTERIOR 

FRED A. SEATON, Secretary 

GEOLOGICAL SURVEY 

Thomas B. Nolan, Director 

For sale by the Superintendent of Documents, U.S. Government Printinl!\ Office 

Washington 25, D. C. 
CONTENTS 

Page 

Abstract---------------------------------------------------------- 1 

Introduction------------------------------------------------------ 3 

Acknowledgments------------------------------------------------- 4 

GeographY-------------------------------------------------------- 5 

Surface features ____ ------------------------------------------- 5 Climate and vegetation ____________________ -- _____ --- ___ ---_____ 7 

Transportation------------------------------------------------ 9 

British Honduras _____________ ---- __________ ----_-----_____ 10 

Guatemala------------------------------------------------ 10 

ElSalvador----------------------------------------------- 10 

Honduras------------------------------------------------- 11 

~icaragua------------------------------------------------ 11 

CostaRica----------------------------------------------- 12 

Panama and the Canal Zone-------------------------------- 12 

GeologY---------------------------------------------------------- 13 

Previouswork------------------------------------------------- 13 

Stratigraphy of northern Central America________________________ 14 

Pre-Permian rocks_________________________________________ 14 

Rocks of Paleozoic age------------------------------------- 14 

Permian system_______________________________ _ _ _ _ _ _ _ _ 15 

Santa Rosa formation______________________________ 15 

Chochallimestone ______________________ ---- _ _ _ _ _ _ _ 16 

Pre-Cretaceous rocks __________________ ----_---_____________ 19 

Rocks of Mesozoic age------------------------------------- 19 

Tertiary system___________________________________________ 23 

Quaternary system ____ -------------------------------_____ 24 

lgneousrocks_____________________________________________ 25 

Intrusive rocks________________________________________ 25 

Volcanic rocks _______ ---------- __ ------------------___ 26 

Stratigraphy of southern Central America_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 28 

Pre-Tertiary rocks_________________________________________ 28 

Rocks of Mesozoic age------------------------------------- 29 Tertiary system ________________________ .:.__________________ 29 

Quaternary system ___ ------------------------------------- 32 

lgneousrocks_____________________________________________ 32 

Geologic structure_------------- ___ ------- ____ ------------------___ 33 

Ore deposits _________ ------ ____________ ----- _______________ .._______ 36 

History of mining ____ --------- _________________________ -----__ 36 

Antimony deposits _________ ----- ______________ -----------______ 38 

Honduras-------------~----------------------------------- 39 

El Quetzal mine_______________________________________ 39 

Geology__________________________________________ 40 

Description of the ore bodies________________________ 40 

Suggestions for further prospecting__________________ 43 

m 
IV CONTENTS 

Ore deposits-Continued 

Antimony deposits-Continued 

Honduras-Continued Page 

Benjamin mine________________________________________ 44 

Siria mine ________________________ ------------- __ ----- 44 

Los Hornitos mine ______ ;_______________________________ 44 

Las Flores deposits _________________________________ --- 45 

San Fernandez mine_---------------------------------- 46 

San Francisco mine____________________________________ 46 

La Uni6n mine ________________ ------------------------ 46 

(}uatemala________________________________________________ 47 

Las Tablas deposit_____________________________________ 47 

El Carrizal prospect ___ -------------------------------- 47 

ElHornoprospect_____________________________________ 47 

Nicaragua------------------------------------------------ 47 

La Cadena prospect----------------------------------- 47 

Chromite deposits ______________________________________ ----___ 48 

Guatemala------------------------------------------------ 48 

Production------------------------------------------- 48 

GeologY---------------------------------------------- 49 

Description of the ore deposits-------------------------- 50 

Jalapa district_____________________________________ 51 

La Gringa mine_______________________________ 51 

Corona mine_______ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 51 

La Paz mine ______ ---------------------------- 52 

Cabanas district___________________________________ 52 

La Joya mine ____ ----------------------------- 53 

La Corona deposits____________________________ 53 

Buenos Aires mine_____________________________ 54 

SanJuan prospect----------------------------- 54 

San Juancito prospect__________________________ 54 

El Audiencio deposit___________________________ 54 

San Antonio deposits--------------------------- 55 

Other deposits ______ ----- __________ ----------- 55 

Pasasaguas district ___ ----------------------------- 55 

El Retiro district _________ -- __ ----_------- ____ ----- 55 

Copper deposits ___ ----- ____ -------------------- ___ ---------___ 56 

Guatemala------------------------------------------------ 56 

San ~ateoprospect------------------------------------ 56 ~ataquescuintla mine _____________ ---- __ -----__________ 56 

Los Sandillales prospect_ ____________________ ------------ 57 

Zuh6j deposits __ ------ ______________ ----- _________ ---- 57 

Cerro Vivo prospect----------------------------------- 58 

Other deposits________________________________________ 58 

1Ionduras------------------------------------------------- 58 

El Amatillo prospect___________________________________ 59 

Petoa deposits _______ ---- _______ -~- _________ --________ 59 

~acutlaprospect______________________________________ 60 

Lorna Chamuscada deposit ______ ------------ __ --------- 60 

Las Chacaras mine _____ ------------ __ ------------_____ 60 

SantaCruz prospect___________________________________ 61 

.Other deposits_________________________________ __ _ _ _ _ _ 61 
CONTENTS · Y, 

Ore deposits-Continued 

Copper deposits-Continued P,ge. 

CostaRica----------------------------------------------- 61 

Aguacate district______________________________________ 61 

Monte del Aguacate mine__________________________ 61 

Puriscal area___ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 61 

Guayabo deposits---------------------------------- 62 

San Rafael deposits-------------------------------- 62 

Nicaragua------------------------------------------------ 62 

Rosita mine ___________________ ------- _______ -------___ 82 

Iron depoffits-------------------------------------------------- 64 

IIonduras------------------------------------------------- 64 

Agalteca deposits _________________ --------_____________ 64 

GeologY------------------------------------------ 64 

Group P------------------------------------------ 67 

Group Q----------------------------------------- 68 

Group B----------------------------------------- 68 

Group C----------------------------------------- 69 

Group 0----------------------------------------- 70 

Reserves and outlook for additional discoveries________ 71 

Aramecina deposits ___ -------------------------------__ 71 

Nicaragua------------------------------------------------ 72 

Rosita area ______________________ --------------_______ 72 

Otherareas------------------------------------------- 12 

Guatemala------------------------------------------------ 72 

Costa Rica_______________________________________________ 72 

Lead-zinc deposits ________________________ -------______________ 73 

Guatemala and El Salvador--------------------------------- 73 

GeologY---------------------------------------------- 73 

Description of the ore deposits__________________________ 73 

Meta pan district __ -----------------------------___ 74 

San Juan mine_------------------------------- 74 

San Casimiro mine_____________________________ 76 

El Tajado mine_______________________________ 76 

San Isidro Montafiita prospects __ --------------- 77 

El Brujo mine_________________________________ 77 

La Esperanza prospect ___ -------------------___ 77 

Chaguite deposits ___________________ .:.__________ 77 

Monte Verde deposit_ _____ ~-------------------- 78 

Other deposits ___________________ --------_____ 78 

Alotepeque district _______ ----------------------___ 78 

San Pantale6n mine____________________________ 79 

Santa Rosalia mine _________ ------------------- 80 

Plomosa Grande mine__________________________ 80 

Tajo de Montenegro mine______________________ 80 

La BaHena mine_______________________________ 80 

San Jose Grande mine__________________________ 81 

Santa Sofia mine __ ---------------------------- 81 

San Fernando mine____________________________ 81 

El Chorro mine_______________________________ 82 

San Bartolo mine______________________________ 82 

Other mines ___ --------------------------_____ 82 
CONTENTS 

Ore deposits-Continued 

Lead-zinc deposits-Continued Page. 

Ctuatemala________________________________________________ 83 

Treatment of the ore___________________________________ 83 

Local terminology of the ores___________________________ 84 

Chiantla-San Sebastian district ___________ --------------- 84 

Cteology__________________________________________ 85 

Description of the ore deposits______________________ 87 

Torl6n mine__________________________________ 87 

Chochruprospect______________________________ 90 

Mineral de Ocre mine__________________________ 91 

Tziminas mine________________________________ 91 

La Sara mine_________________________________ 92 

La Esperanza mine____________________________ 92 

Other mines ____ ------------------------------ 94 

San Miguel district ___________________ ------___________ 94 

CteologY------------------------------------------ 95 

Description of the ore deposits______________________ 95 

Rosario mine ___________________ --------------- 96 

Bola de Oro mine______________________________ 97 

Villa Linda mine __ ---------------------------- 97 

Other deposits ______________ ---------_------_- 99 

Cohan district ____________________ --------------------- 99 

CteologY------------------------------------------ 100 

San Joaquin mine ____ ----------------------------- 101 

Santo Domingo mine_______________________________ 102 

Pampujmay mine__________________________________ 102 

Sepacay deposit----------------------------------- 102 

Suquinayprospect_________________________________ 103 

La Camelia prospect_______________________________ 103 

Sequilha prospect_ __________________________ ------_ 103 

Caquipec mine_----------------------------------- 104 

San Sebastian deposits ________ --------------------_ 104 

Manganese deposits____________________________________________ 104 

Costa Rica----------------------------------------------- 105 

Cteology______________________________________________ 105 

Descriptjon of the ore deposits-------------------------- 105 

Panama, by FrankS. Simons------------------------------- 106 

Bahia de Mandinga area ___ ---------------------------_ 106 

Cteology__________________________________________ 108 

Description of the ore deposits_--------------------- 109 

Rio Navagana deposits_________________________ 109 

Mine 1--------------------------------------- 110 

Mine2--------------------------------------- 110 

Mine3--------------------------------------- 111 

Mine4--------------------------------------- 111 

Nombre de Dios area__________________________________ 111 

Cteology__________________________________________ 113 

Mines along the Rio Fat6 ___ ----------------------- 113 

Mostroncosa deposit___________________________ 113 

Mangue de Indio prospect______________________ 114 

Panama (Ventura) prospect--------------------- 114 

Machita deposit ________ ----------------------- 115 

Blaqueprospect------------------------------- 115 

La Mesa prospect_____________________________ 116 
CONTENTS vn 

Ore~ deposits-Continued 

Manganese deposits-Continued 

Panama-Continued 

Nombre de Dios area-Continued Page 

Cerro Viejo deposits._---------·------------------- 117 America prospect .. ________________ ._____ _ _ _ _ _ _ _ 117 

Maria:-Defense prospect ___________ '"' ..... __________ 117 

Mtlo;riana deposit __________________ .. __ .,._________ 119 

Juneprospect--------------------------------- 119 

Hyatt area. ___ --------------------------------------- 119 

Hyatt no. 1 mine---------------------·------------ 121 

Hyatt no. 2 mine~-------------------_,. __ ;,._________ 124 

Calzada Larga area ____________________ ._._____________ 128 

Bahia de Montijo-Ponuga area-------.----.. ---------:,_____ 128 

Harriet prospect ___________ ---------.. -------------· 129 

La Matilde deposits-----------------------·--------- 131 

Nuestro Amo _prospect ____ ----------------•-------- 134 

Honduras------------------------------------------------- 135 

La Mesilla area __ .. _----------------·--.. --------------- 136 

Tendalmine______________________________________ 136 

Quebrada de Ruben prospect________________________ 137 

Malachateprospect________________________________ 138 

Cerro Bonito prospect-----------·------------------- 138 

Sabanagrandearea_____________________________________ 138 

Villa Nueva area _________________________ ~------------ 138 

Flor Azul prospect_________________________________ 139 

Ojojona. deposits ________ -------------------------__ 139 

El Apintal prospect-------------------------------- 140 

Other deposits ___ ---- ____ ------------------------- 140 

Guatemala________________________________________________ 141 

Perezprospect---------------------------------------- 141 

Brenesprospect--------------------------------------- 141 

La Cumbre deposits ____ ------------------------------- 141 

Mica deposits_________________________________________________ 142 . Guatemala _______________________________ ------... .:._________ 142 

Geology ________________________________________ ._____ 143 

Properties of Guatemalan muscovite_____________________ 145 

Pachalum district ____________________________ .... ________ 148 

Palibatz mines __ ---------------------------------- 148 Palibatz no. 1 mine __________________ ..;_________ 149 

Palibatz no. 2 mine____________________________ 151 

El Anono no. 1 mine------------------------------- 152 

El Anono no. 2 mine------------------------------- 152 

Xeabaj mine______________________________________ 153 

El Cipres no. 1 mine ___________________________ .. ___ 153 

El Cipres no. 2 prospect____________________________ 154 

Los Volcancillos prospect--------------------------- 154 

Santa ~a prospect------------------------------- 155 

El Jocote prospect.--------------------------•----- 155 

Tzitzil prospect. _________________________ --------- 155 

Sechunprospeet___________________________________ 156 

Talaxc6cprospect_________________________________ 156 

Los Tablones prospect ____ ------------------------- 156 

Quiac6j prospect .. ___ ------------------------------ 156 
vm CONTENTS 

Ore deposits-Continued 

Mica. deposits-Continued 

Guatemala-Continued Page 

Agua Caliente district__________________________________ 157 

La Adilia mine------------------------------------ 157 

La Constancia mine _____ --------·------------------ 157 

La Virginia mine_------ ___ ------------------------ 158 

LaEsperanzamine-------------------------------- 158 

Nueva Wellington mine _____ ----------------------- 159 

La Cabrera mine_---------- _______________ :________ 159 

Libertad and Margareta prospects____________________ 160 

El Perez no. 1 mine________________________________ 160 

El Pino prospect ____ ------------------------------ 160 

Quartz deposits ______ ------ ____ ------- _____________ ----------_ 161 

Guatemala------------------------------------------------ 161 

Geology----- ______ ----------- ____ --------- _____ ------- 162 

El Chol.area_ _ _ _ _ _ _ _ _ __ _ _ __ _ _ _ _ _ _ _ _ __ _ _ _ _ _ __ _ _ _ _ ___ _ _ _ 164 

Santa Lucia mine__________________________________ 164 

Los Limones mine ____ ------ __________ ------------- 165 

Trapiche Viejo mine------------------------------- 165 

Los Amates deposit-------------------------------- 165 

Itabinalarea__________________________________________ 166 

Toloxcoco mine ____ ------------------------------- 166 

Chipacapoxmine---------------------------------- 166 

Cubulco area _____ ------------------------------------- 167 

Jeeulmine---------------------------------------- 167 

Izotrumine_______________________________________ 167 

SanJuanprospect--------------------------------- 167 

Chirruman prospect_ ____ -------------------------- 168 

. El Cand6n prospect------------------------------- 168 

- Pomaxan prospect--------------------------------- 168 . Paraxaprospect___________________________________ 168 

Chautulul prospect _______ ------------------------- 168 

Dolores deposit _____ ------------------------------ 169 

Other deposits ___ --------------------------------- 169 

Quicksilver deposits ______ ------------------------------------- 169 

IIonduras------------------------------------------------ 169 

Los Izotes mine __________________ --------------------- 169 

La Canada mine _____ --------------------------------- 170 

PazdeposUs------------------------------------------ 172 

Coyolito prospect ___________ ---------- ________ ----- 173 

Venadoprospect---------------------------------- 173 

Capitan prospect ____ ------------------------------ 173 

Guatemala and El Salvador_________________________________ 174 

Gold and silver deposits ___________ ----------------------------- 17 4 

Production __________________ ..:. __ --------- ____ ------------- 175· 

IIonduras------------------------------------------------- 175 

El Rosario mine ____ ----- _________ ----- _____ ----------- 175 

Agua Fria mine __ ------------------------------------- 176 

San Andres mine______________________________________ 178 

Anderson and Rey del Oro mines------------------------ 178 

Mangulile mines_______________________________________ 178 

Opotecamine----------------------------------------- 178 

Other deposits in northwestern IIonduras_________________ 179 
CONTENTS 

Ore deposits-Continued 

Gold and silver deposits-Continued 

Honduras-Continued 

San Felix mine _______________________________________ _ 

La Victorina mine ________________ ----- ___ --------- ___ _ 

Conchagua mine _________ ----- ______ -:-----·-----------_ 

La Alhambra mine _________ ---------------.,~~----------

Santa Lucia and Valle de Angeles mines __ :---------------- Montafi.ita and San Antonio de Oriente jdeposits __________ _ 

Yuscaran deposits __ --- ___________ -----:----- __ ----- ___ _ 

Sabana Grande mines __________ ------------------------

El P6rvenir mine _________________ ---- __ --------------_ 

El Transito mine ______________________ ----------- ____ _ 

San Martin deposits ______ -----------------------------

El Corpus deposits ________________ --------------------_ 

Tatumbla mine _____________ ---------------------------

El Mochito mine __ ------------------------------------

Quitagana mine __ -------- __ --------------------------- Placer deposits _______________ ---------------------- __ _ 

Rio Guayape and Rio Jalan placers------------------

Costa Ri~~~e~ -~~~~~~~ -_ ~ = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = Aguacate district ____________________ ; ___ --------------_ 

Abangares district ___________________ , ___ -- ___ ------- __ _ 

Miramar and Esparta districts __ ------------------------ Peninsula de Osa area _________________________________ _ 

Nicaragua ____________________________ --·-----------------_ La Luz mine ________________________ , _________________ _ 

Pis Pis district ______________________ ----- ____ ---------

Chontales district ____________________ , _____ -------------

Matagalpa area __ ------------------------------------- La India mine ________________ ------------------ __ _ 

El Lim6n mine _______________ ---------- ____ -------

Verde mine __________________ ------------ ________ _ 

San Albino mine __________________________________ _ 

Other areas ___________________ ------·------------------

El Salvador-----------------------------------------------

San Sebastian mine ___________________________________ _ 

Divisadero mine _____________________________ ----------

Hormiguero mine _____________________ -----------------

Monte Mayor mine __________________ , ___ ---------------

Potosf mine ____________________ ------ __ ------ ________ _ 

Monte Cristo mine ___ ---------------1------------------

El Dorado mine ____ ----------------------------------- Guatemala ___________________________ ------------ __ -------

La Canoa placer deposits ______________________________ _ 

Las Quebradas placer deposits---------,------------------

Panama--------------------------------1------------------ V eraguas mines ____________________ + ________________ _ T Placer .deposits ____________________ -~- ________ ------ __ _ 

ungsten deposits __ • _______________________ .... _______ -------- __ _ 

References cited ________ .. ______________________ ----- __ -------------

Metric equivalents ______________________________ :---_---------------

IndeX------------------·------------------------------------------

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X CONTENTS 

ILLUSTRATIONS 

[Plates in pocket] 

PLATE 1. Geologic map of Central America. 

2. Topographic map of Central America. 

3. Composite level map of the El Quetzal antimony mine, 

Honduras. 

4. Geologi'c map and sections of the El Quetzal antimony mine, 

Honduras. 

5. Index map, geologic maps, and sections of the Corona, La 

Joya, La Paz, and La Gringa chromite mines, Guatemala. 

6. Geologic map and sections of the Agalteca area, Honduras. 

7. Geologic map and sections of the groups B, C, 0, P, and Q 

iron-ore bodies, Agalteca area, Honduras. 

8. Index map, geologic map, and section of the Alotepeque district, Guatemala. 

9. Geologic map of the Chiantla-San Sebastian district, Guatemala. 

10. Map of the Torl6n mine workings, Guatemala. 

11. Maps of the Rosario mine area, Guatemala. 

12. Geologic map of the Villa Linda mine, Guatemala. 

13. Index map showing location of mica mines, Joyabaj and 

Granados area, Guatemala. 

14. Geologic map and section of Palibatz no. 1 mica mine and 

geologic maps of the Palibatz no. 2 and El Anono no. 1 mica 

mines, Guatemala. 

15. Sketch maps of the workings of the La Constancia, La Adilia, 

Nueva Wellington, La Esperanza, and La Virginia mica 

mines, Guatemala. 

16. Sketch maps of the Toloxcoco, Xeul, Los Limones, and Santa 

Lucia quartz mines, Guatemala. Page 

FIGURE 1. Geologic map of the El Quetzal antimony mine, Honduras____ 39 

2. Projected longitudinal profile of the El Quetzal antimony 

mine, Honduras __________________________ ------------_ 42 

3. Map of the San Juan mine workings, El Salvador___________ 75 

4. Index map showing locations of mines in the Cohan district, 

Guatemala___________________________________________ 83 

5. Map of the La Esperanza mine workings, Guatemala________ 93 

6. Geologic map of the San Joaquin mine workings, Guatemala__ 101 

7. Sketch maps of the Bahia de Mandinga manganese deposits, 

Panama---------------------------------------------- 107 

8. Managanese deposits in the N ombre de Dios and the Rio 

Boquer6n areas, Panama ____ -------- __ ----------------- 112 

9. Map of the Hyatt no. 1 manganese mine, Panama___________ 122 

10. Map of the Hyatt no. 2 manganese mine, Panama___________ 125 

11. Map of the Harriet manganese deposits, Panama____________ 130 

12. Map of the La Matilde manganese deposits, Panama_ _ _ _ _ _ _ _ 132 

13. Map of the Tendal workings, La Mesilla area, Honduras_____ 136 

14. Map of Cubulco, Guatemala, showing location of the quartz 

mines________________________________________________ 161 

15. Geologic map and section of the La Canada quicksilver mine, 

Honduras-------------------------------------------- 171 
MINERAL DEPOSITS OF CENTRAL AMERICA 

By RALPH J. RoBERTS and EARL M. IRVING 

ABSTRACT 

The mineral deposits of Central America were studied between 1942 and 

1945, in cooperation with tlb.e United States Department of State and the Foreign 

Economic Administration. Emphasis was originally placed on the study of 

strategic-mineral deposits, especially of antimony, chtomite, manganese, quartz, 

and mica, but deposits o:E other minerals that offered promise of significant 

future production were also studied. A brief appraisail of the base-metal deposits 

was made, and deposits of iron ore in Honduras and of lead and zinc ores in 

Guatemala were mapped.. In addition, studies were made of the regional 

geology of some areas, data. were collected from many sources, and a new map 

of the geology of Central America was compiled. 

Central America comprises three principal physiographic belts: a northern 

belt of folded mountains extending through central Guatemala and northern 

Honduras and into Nicaragua, a middle belt occupied by a dissected volcanic 

plateau extending from Guatemala eastward through El Salvador and across 

southern Honduras into Nicaragua, and a southern belt of folded strata and 

volcanic rocks in Costa Rica and Panama. 

In northern Central America the folded mountains are composed of gneiss, 

schist, quartzite, and marble, which have been intruded by granitic rocks. 

These rocks are overlain by Permian ( ? ) and Permian sedimentary rocks and are 

cut by later granitic rocks and serpentine of supposedly late Permian or early 

Mesozoic age. Marine and continental sediments of Jurassic, Cretaceous, and 

Tertiary age, and lavas and pyroclastic rocks of Cretaceous and Tertiary age, 

overlie the rocks of Paleozoic age. 

The volaanic plateaus in middle Central America consist mostly of late 

Mesozoic and Tertiary la"ras and pyroclastic rocks, but older rocks are· exposed 

locally where erosion has been deep or where these rocks were never completely 

buried. Volcanic activity began in Cretaceous time and continued intermittently 

during the Tertiary, probnbly reaching a maximum during the Miocene and becoming less intense during the Pliocene and early Quaternary. Several volcanoes 

are still active. 

In southern Central America folded Tertiary marine and continental sediments 

rest on a basement complex of pre-Eocene sedimentary, metamorphic, intrusive, 

and extrusive rocks. The Tertiary basins varied greatly in form, and the rock 

units deposited in them are so highly lenticular that it is difficult to correlate 

from one basin to another . 

.A:ntimony deposits are found in Honduras and ad,acent parts of Guatemala, 

in central Guatemala, and in western Nicaragua. On~y the Honduras deposits have 

thus far been productive ; the total production has n about 700 tons of metal• 

lurgical and chemical ore. The El Quetzal mine in w tern Honduras has yielded 

more than 80 percent of this total. Here the antimony ore is in fault zones that 

cut graphite schist and intrusive rocks. 

1 
2 MINERAL DEPOSITS OF CENTRAL AMERICA 

Chromite deposits have been found in the Jalapa, Cabanas, and Santa Rosa 

districts in Guatemala. These have yielded about 9,850 long tons of chromite ore 

of metallurgical grade, containing from 48.31 to 59.97 percent Cr20a and with 

a chromium-to-iron ratio of from 2.70 to 3.96. The ore forms lenses that contain 

from a few tons to 2,000 tons each in sheared serpentine. 

Copper properties are known in Guatemala. Honduras, Nicaragua, and Costa 

Rica. The Rosita properties in eastern Nicaragua had reserves in 1955 totaling 

about 2 million tons that averaged 3.9 percent copper. The deposit was formed 

by contact matesomatism, and ore was concentrated by oxidation and supergene 

enrichment. 

Iron deposits are found in Guatemala, Honduras, Nicaragua, and Costa Rica, 

but only the Agalteca deposits, in central Honduras, have a notable reserve. 

The ore is magnetite and hematite which replace limestone and hornfels adjacent 

to intrusive diorite. The inferred reserves total about 8 million tons, averaging 

about 53 percent iron, 0.01-0.08 percent phosphorus, 0.02 percent sulfur, and 10 

percent silica. Because of their remoteness from the coast and the lack of transportation facilities, the deposits have not been exploited, but an increase in the 

market price may make the deposits workable in the future. 

Lead-zinc deposits are being worked in the Departamentos de Huehuetenango 

and Alta Verapaz in Guatemala. The Chiantla district in Huehuetenango has 

been mined intermittently since colonial days, and the San 1\::liguel district, also 

in Huehuetenango, has been worked since about 1915. The lead-zinc ore bodies 

replace limestone and dolomite of Permian and Cretaceous age. Near the 

surface the ore has largely been oxidized to lead and zinc carbonates, but primary sulfides are found at depth. The outlook for future production is promising, provided transportation facilities are improved. Lead-zinc deposits near 

Cohan in Alta Verapaz were being explored in 1946, and shipments were started 

early in 1949. Deposits are also known in the Departamento de Chiquimula and 

adjacent parts of El Salvador ; one deposit in the Meta pan district was put 

into production in 1950. 

Deposits of manganese ore in Costa Rica and Panama have been worked intermittently and have yielded about 97,000 long tons of metallurgical ore. The 

ore bodies consist principally of manganese oxides derived from manganese 

carbonates and silicates. Individual ore bodies contain from a few tons to 

several thousand tons. As the known ore bodies of commercial grade have 

been mostly mined out, the outlook for future production is not promising. 

Mica deposits were mined in central Guatemala between 1918 and 1942; the 

production, about 100,000 pounds of sheet mica, was used largely fo;r electrical 

purposes. Most of the mica is green or bottle green and undesirable for use in 

condensors. A small quantity of ruby and rum condensor mica was also produced. 

Under the stimulus of high prices between 1941 and 1944, about 1,000 pounds 

of radio quartz was produced in Guatemala. The quartz was in lenticular 

veins in metamorphic rocks ; the usable crystals ranged in weight from less than 

a pound to 52 pounds. Most of the quartz was classified as grade 2 or 3. 

Production of gold and silver in Central America during recent years has 

been greatest in Nicaragua, where the total value is about $8 million yearly, 

chiefly gold. Honduras is second, with a production of about $3 million yearly, 

chiefly silver. Most of the veins are of Tertiary age and were probably related 

to middle Tertiary volcanism. Some of the veins are older and were probably 

formed during the intrusive periods of Paleozoic and Mesozoic time. 
MINERAL DEPOSITS OF CENTRAL AMERICA 3 

INTRODUCTION 

This report is based on investigations carried on by the Geological 

Survey (U.S. Department of the Interior) under the auspices·of the 

Interdepartmental Committee on Scientific and Cultural Cooperation 

(U. S. Department of State) and the Foreign Economic 

Administration. The function of the last two agencies is presently 

carried on by the International Cooperation Administration. Roberts 

is responsible for the text of this report and for the compilation of 

the geologic map (pl. 1). He was in Central America from January to 

April 1942 under a program of scientific and technical cooperation 

with the American Republics sponsored by the Department of State, 

and mapped manganese deposits in Costa Rica and manganese and 

antimony deposits in Honduras. From December 1942 to May 1945 

he was assigned by the Geological Survey to the Central American 

Minerals Mission of the Foreign Economic Administration .under .the 

direction of William C. Schmidt, and mapped deposits of lead, zinc, 

mica, and quartz in Guatemala; antimony, iron, and mercury in Honduras; lead, zinc, and copper in El Salvador; ·and iron, copper, and 

antimony in Nicaragua. 

Irving, attached to the Foreign Economic Administration, was in 

Central America from December 1942 to February 1945. He n1apped 

copper deposits in Guatemala and Costa Rica and chromite and iron 

deposits in Guatemala, and assisted Roberts in mapping iron deposits 

in Honduras and lead-zinc, mica, and quartz deposits in Guatemala. 

Prior to World War II Irving had been engaged in gold mining in 

Honduras. His first hand knowledge of many' mines has been incor .. 

porated in the present report, and it has been supplemented by the 

published data available. 

In addition, the work of many others is included in this report. 

Among the contributors are William C. Schmidt and Lawrence G. 

Houk, mining engineers, attached to the Central American Minerals 

Mission, who each contributed several reports which are incorporated 

here. Philip W. Guild and FrankS. Simons of the Geological Survey did field work in Central America under the program sponsored by 

the Department of State. Guild examined chromite and antimony 

deposits in Guatemala in 1942, and Simons mapped manganese 

deposits in Panama during 1942 and 1943. Fred H. Dakin, consulting 

engineer, examined antimony deposits in Honduras in 1941 and made 

his reports available to the Foreign Economic Administration. 

In accordance with the program for procuring strategic minerals in 

Latin America, carried on between 1942 and 1945 by the Foreign Economic Administration under the direction of Alan M. Bateman, the 

writers visited many mines, prospects, and deposits in mineralized 
4 MINERAL DEPOSITS OF CENTRAL AMERICA 

areas. For the most part only brief examinations were made, although 

some promising properties and districts were mapped or studied in 

detail. The main emphasis was on the examination of deposits containing strategic minerals, but some other deposits that offered hope of 

postwar development were also studied, and a few gold and silver mines 

were visited during the course of other work. Descriptions of the deposits are arranged alphabetically according to commodities and are 

subdivided on the basis of geographic location. 

ACKNOWLEDGMENTS 

The writers are greatly indebted to many who aided in field work and 

furnished valuable data. Among these men are Graham Nelson, D. N. 

Spencer, Rafael Hueso, Fern Kettel, Frank Cameron, T. N. Slaughter, 

Alfred Kirkland, and Donald McDonald in Nicaragua; K. M. Matheson, P. W. Hyde, R.N. Reinninger, Eduardo da Costa Gomez, Salvador 

Lopez, S. M. Waller, Vernon Grove, Fernando Ferrari, Guy R. 

Molony, Juan Baretto, Rudolph Nater, Manuel Bueso, and Dona 

Carmen, v. de Carfas in Honduras; Helmut Meyer-Abich, Rene Keilhauer, T. W. Thompson, Valdemar Raun, Mario Sol, Rafael Lima h., 

Daniel Basauri, Paul Crawford, Carlos Sagrera, Raoul Salavarria, 

and Hjalmar Samuelson in El Salvador; Antonio Eskanasy, Virgilio 

Recinos, Humberto Recinos, Robert H. Sayre, Delfino Sanchez Latour, 

Luis Leysbeth, Alejandro Synegub, Jose Tomas Rodas, Eduardo 

Goyzueta, Florencio Santiso, Jose I ten, Antonio Rodriguez, Rodolfo 

Vegas, Gonzalo Vidal, W. E. Dieseldorff, Adolfo Benz, Carlos Guzman, 

and Francisco Mota in Guatemala; Alfonso Segura, Max Esquivel, 

Fabio Fournier, Enrique Fournier, Adan Rodriguez, W. R. Scott, 

Plato Malozemo:ff, Arturo Fernandez, Gabriel Dengo, Cleto Moraga, 

and Antonio Rosales in Costa Rica; and J. Huertematte in Panama. 

Many others who acted as guides and field assistants deserve special 

thanks for their cooperation and loyalty under difficult conditions. 

Rudi N ater and Javier Galindo, who acted as field assistants on the 

longer investigations, rendered valuable aid and did much to expedite 

the work. 

Officers of the United States Department of State and of the Foreign 

Service, without exception, cooperated wholeheartedly with the 

authors in working with government officials of the Central American 

countries. 

Officials of the governments of the countries of Central America 

gave unfailing cooperation and placed all possible facilities at the 

authors' disposal. At times they furnished guides, field assistants, 

and transportation when these were not otherwise available. 
MINERAL DEPOSITS OF CENTRAL AMERICA 5 

GEOGRAPHY 

Central America (pls. 1, 2) comprises the six independent republics 

of Guatemala, El Salvador, Honduras, Nicaragua, Costa Rica, and 

Panama; the British colony of British Honduras; and the Panama 

Canal Zone. These countries extend southeastward in an S-shaped 

curve from lat 18°3' -7°12' N. and from long 77°15' -95°10' W. Centra~ 

America is 1,300 miles long (see Metric Equivalents, p. 199) measured 

along its axis, and its width ranges from 31 miles at the narrowest 

part of the Isthmus of Panama to about 300 miles across the widest 

part of Nicaragua and Honduras. · 

The populations, areas, and capital cities of the Central American 

countries are summarized below (U. S. Bureau of Foreign and. 

Domestic Commerce, 1942, 1943a). 

Country 

Area (approximate) Population (l!MO) " Capital 

Sqmile Sqkm. 

Guatemala ____ ------- ___ 48, 290 125, 071 3,284,269 Guatemala Ci.ty. Honduras _______________ 46,332 120,000 1,105,504 Tegucigalpa. El Salvador _____________ 13, 176 34,000 1, 787,930 San Salvador. Nicaragua ______________ 49,200 127,430 1,380,287 M.anagua. Costa Rica ______________ 23, 160 60,000 639, 197 San Jose. Panalna ________________ 33,667 86,902 631,637 Panama. 

Canal Zone __ ----------- 502 1,300 51,287 British Honduras ________ 8,598 22,270 45,000 Belize. 

SURF ACE FEATURES 

Central America may be considered, for convenience, as comprising 

three principal physiographic units (pl. 2): a northern unit of mountains of old folded rocks, extending through northern Guatemala ahd 

northern·Honduras into Nicaragua; a middle unit consisting of a dissected volcanic plateau, extending from central Guatemala eastward 

through El Salvador and southern Honduras; and a southern unit of 

folded strata and volcanic rocks in Costa Rica and Pandma. , 

Each of these major units can be subdivided into physiographic 

provinces. The northern unit contains the· Peten lowland and the 

Antillean cordillera; the middle unit, the upper Pacific cordillera and 

the Guatemala-El Salvador coastal plain; and the sou the~ unit, the 

Nicaraguan lowland, the Costa Rica coastal plain, 'the central cordill~ra of Costa Rica and Panama, and the Pacific coastal plain. 

The Peren lowland, which is underlain by folded Tertiary rocks, 

ranges in altitude from about 500 feet on the west to 2,000 feet on tlie 

east and south where it merges with the Antillean cordillera. · 

The Antillean cordillera is a ~lt of folded Cretaceous and older 

rocks that extends through central Guatemala and· Honduras into 
6 MINERAL DEPOSITS OF CENTRAL AMERICA 

Nicaragua. These mountains rise to about 13,400 :feet in western 

Guatemala, and they everywhere constitute rugged, deeply dissected 

ranges whose average altitude is more than 4,000 :feet. 

The upper Pacific cordillera is a dissected volcanic plateau extending 

from Chiapas, Mexico, through southern Honduras and El Salvador 

into central Nicaragua. The altitude o:f this plateau ranges :from 

10,000 feet in western Guatemala to 8,000 :feet in Gracias, Honduras; 

it drops to 4,000 :feet in Nicaragua, where the upland slopes southward 

to the ocean. Volcanoes built upon this plateau by Tertiary and 

Quaternary volcanism are alined along its southwestern border; the 

highest is Tacana, 13,816 :feet in altitude, at the Mexico-Guatemala 

boundary line. The plateau is only partly dissected in Guatemala, 

whereas in El Salvador and Honduras its dissection is so advanced 

that few remnants o:f the original upland surface remain. The plateau 

is bordered on the north in Honduras and Nicaragua by a coastal plain, 

which, although absent in the places where the ranges are truncated 

at the coastline, elsewhere ranges in maximum width from 15 miles in 

Honduras to 50 miles in Nicaragua (Bengston, 1926, p. 403-413). 

The broad alluvial plain extending southward up the Rio illua 

valley is a graben, which is part of the prominent transverse fault 

system extending southward into the Golfo de Fonseca. 

The Guatemala-El Salvador coastal plain, which borders the volcanic belt on the southwest, ranges in width :from 35 miles at the Mexican border to 10 miles at the El Salvador border; the plain widens 

again in eastern El Salvador and ends near the Golfo de Fonseca, 

where volcanoes occur in the coastal area. 

The southern part of Nicaragua is separated from the northern part 

by the Nicaraguan lowland, which Hayes (1899, p. 347) interpreted 

as a peneplain cut· on Eocene and younger rocks. Lago de Nicaragua. 

occupies the western part of this depression, having been dammed by 

the volcanoes of the Pacific coastal area. The ranges that make up the 

southwest volcanic chain of the central cordillera rise from the Nicara~ 

guan lowland. 

Costa Rica is bordered on the north by a coastal plain of variable 

width which joins the Nicaraguan iowland on the north and continues 

southward into Panama. The Cordillera Central de Costa Rica is in 

part a volcanic plateau above which volcanoes rise as high as 11,326 

feet. Southward the plateau grades into the rugged and dissected 

Cordillera Central de Talamanca, which is composed of intrusive 

igneous rocks and sediments and which continues southeastward into 

Panama. 

The Pacific coastal plain varies in width but is mostly less than 5 

miles wide. Three peninsular ranges, the Nicoya, the Osa, and the 

Burica, are connected with the mainland by low alluvial plains (Schu-
GEOGRAPHY 7 

chert, 1935, p. 593). On the north these peninsulas _are bounded by 

volcanoes. 

Panama is a continuation of the Cordillera Central de Talamanca. 

Except for a narrow coastal plain in some places, the isthmus consists 

mainly of discontinuous ridges, but a number of volcanoes rise above 

the ridges in northwestern Panama. 

The Pacific coastal plain in Guatemala is prograding because of the 

enormous volume of detritus that is being carried southward by 

streams· draining the volcanic chain. Farther southeast, in El Salvador, the coastal plain is narrow and has a rugged shoreline that is 

being actively eroded, although raised terraces at about 40 and 100 

feet above sea level indicate that the most recent movements have been 

emergent. 

The Caribbean coastal plain also has recently been uplifted. Near 

Livingston, Guatemala, coral reefs of Pleistocene age are several hundred· feet above sea level, and along the north coast of Honduras and 

the east coast of Nicaragua, uplifted terraces show evidence of Pleistocene and Recent emergence. In Costa Rica and Panama the principal movements have been submergent, although local Recent emergence is indicated by raised terraces. 

C~Jl,YIATE AND VEGETATION 

The climates of Central America are varied: a tropical rain-forest 

climate on the Caribbean coast, a savanna climate on the Pacific coast~ 

and a highland climate in the interior uplands (Trewartha, 1943, p. 

317-356, 501-513). These variations, caused -by the high rugged 

mountains that follow the axis of Central America, make most parts 

of the region both pleasant and healthful. 

In Central America, three temperature zones are comn1only recognized : the tierra caliente (hot region) , generally extending from sea 

level to about 2,500 feet; the tierra templada (temperate region), extending from 2,500 feet to about 6,500 feet; and the tierra fria (cold 

region), which extend-s from 6,500 feet to 14,000 feet. However, in 

southeastern Central America the hot region extends to about 4,000 

feet, and although some mountains reach 8,000 feet in altitude they 

are still in the temperate region, there being no cold region. 

The tropical climate of the Caribbean coastal belt is characterized 

by a high annual rainfall, which ranges from about 80 inches to as· 

much as 297 inches. The rain is brought in by the trade winds from· 

the Caribbean Sea; the rainfall is distributed throughout the year,. 

but the months with heaviest precipitation are from June to December. The vegetation of the coastal belt is a tropical rain forest co11·-

taining an evergreen broadleaf flora that includes tree ferns, pahns,' 

mahogany, chicle, and many other species. Trees as much as 150 feet 

388364-5J7-2 
8 MINERAL DEPOSITS OF CENTRAL AMERICA 

high are common, and climbing vines, lianas, and parasitic vegetation, 

together with a heavy undergrowth, create a dense canopy of shade 

with only a subdued light beneath. 

The temperature range in the tropical rainy belt depends upon the 

altitude: at the coast the mean temperature is about 80° F., and the 

annual range is 65°-95° F.; in the mountains the mean temperature 

range is 65°-75° F. Streams are abundant in this zone and flow year 

round; on the low lands and coastal plains, broad flood plains are characteristic (Reed, 1923, p. 133; Shelford ( chm.) and others, 1926, p. 

596-622). 

On the Pacific slope the rainfall is unevenly distributed throughout 

the year and there are distinct wet and dry seasons. The annual rainfall ranges from 60 to 100 inches. The heavy rains fall between May 

and November, when southerly winds prevail; during the intervening 

months some places are completely without rain, although light rains 

generally fall in the months just after and before the heavy rains. 

In many places a 2-week dry spell, the canicula or veranillo, breaks 

the rainy season in August. 

The seasonal distribution of rainfall gives rise to a savanna climate. 

The savanna is principally a grassland with scattered clumps of trees. 

On the margins the clumps become closer, forming a forest that 

merges on its borders into the tropical rain forest. In most places the 

trees are deciduous, but, where rainfall is light, they give way to cactus and scrub brush. 

Temperatures in the sa.vanna are comparable to those of the tropical rainy belt but rise somewhat higher during the dry months. 

Streams show marked seasonal fluctuation, and many dry up during 

the dry season. During the rainy season the streams occasionally become flooded and inundate wide areas of valley bottom. Water supply is often a serious problem during the dry season in the savanna 

areas, although in most places adequate supplies can be developed. 

The highland climates of Central America prevail in the mount'ft.ins 

and plateaus rising above the tropical lowlands. Generally the tropical climate extends up the flanks of the highlands to altitudes of about 

3,000 feet. The rainfall is very unevenly distributed in the highland 

areas, ranging from a few inches a year in some interior valleys to as 

much as 80 inches on the margins of the highland. As on the Pacific 

coast, the wet and dry seasons are distinct, but the climate is cooler; 

in the mountains the minimum temperature is 30° F., and during the 

warmer months maximum temperatures may be 80°-90° F. The vegetation of the highlands is similar to that of many parts of the United 

States : open pine and oak forests characterize the slopes, and many 

high plateau areas are covered with grass. Along the margins of the 

highlands, where the rainfall is greatest, the oak and pine forest 

merges with the rain forest. 
GEOGRAPHY 9 

In northern Honduras and northwestern Nicaragua the oak and 

pine forest is largely confined to the zone between 1,000 and 4,000 feet 

in altitude, and above 4,000 feet the slopes are covered with dense 

evergreen broadleaf forest. To the south, in central Honduras and 

western Nicaragua, the pine forest is best developed between 3,500 

and 5,000 feet above sea level. 

The highland rivers that head in the mountainous areas are commonly perennial, and water supplies are abundant; streams heading 

in plateau areas may be intermittent, and water may be scarce in those 

areas during the dry seasons. 

TRANSPORTATION 

One of the principal problems affecting mining in Central America 

is transportation. Parts of Central America have been developed recently by systems of roads, railroads, and airlines so that movement 

is much less a problem than formerly, but poor transportation is still 

one of the principal deterrents in developing mining properties in 

remote areas. 

In remote areas, supplies for the mines, as well as the minerals 

produced, have to be transported by slow, costly methods. The foot 

trails followed by the Indians and later by the Spaniards were gradually widened and made passable for cars and trucks. In most places 

no attempt has been made to relocate the roads, and consequently they 

are winding and steep where they traverse the rugged mountains of 

the. interior. Torrential showers make maintenance difficult, as most 

of the roads are not surfaced and become badly gullied during wet 

·weather. During the worst part of the rainy season, therefore, most 

roails are impassable, and the best of them are unfit for heavy hauling. 

The Inter-American Highway and feeder roads connecting with it 

,a.re d~igned for all-weather traffic. The low grades on this highway 

wiU greatly cut the cost of transportation and make possible the use 

of heavy hauling equipment. 

Railroads have been built in many parts of Central America, principally during the period 189Q-.1920, when transcontinental lines were 

built cross Panama, Costa Rica, and Guatemala (U. S. Bureau of For-

,eign and Domestic Commerce, 1943b, 1945). The other countries, with 

the exception of British Honduras, are partly covered by railway 

networks. 

The most spectacular development in Central American transporta-

·.tion followed the development of commercial aviation. The airplane 

offers speedy travel to remote areas, many of which had no other means 

.of access, and has played a major role in developing mining opera-

:tions in Honduras and Nicaragua. 
10 MINERAL DEPOSITS OF CENTRAL AMERICA 

BRITISH HONDURAS 

British Honduras has no railways, and access to the interior is byroads or shallow-draft boats. As the rivers are navigable only in 

their lower courses, much of British Honduras is difficult of access 

and is only sparsely settled. A road has been built from Belize northward by way of Orange Walk to Consejo, and branches continuewestward. During the dry season vehicles can travel westward to theGuatemalan border. Other short roads extend inland from the coast 

from Stann Creek, Placentia Lagoon, and Punta Gorda. 

GUATEMALA 

The International Railways of Central America owns the narrowgage railroad that serves most of Guatemala. The main line runsfrom Puerto Barrios on the Caribbean coast through Guatemala City 

to Ayutla on the Mexican border; branches extend to the ports of 

San Jose, Cham peri co, and Ocos on the Pacific Coast. TheEl SalvadorDivision extension of the International Railways turns south at 

Zacapa and enters El Salvador near Meta pan. 

The Verapaz Railway, now operated by the Guatemalan government, serves the Departmento de Alta Verapaz. A combined waterand rail system transports freight by barge from Puerto Barrios and 

Livingston by way of Lago de Izabal to Panz6s, a distance of 110 miles,. 

then by railroad 291h miles to Pancajche. Truck roads passable the 

year around connect Pancajche with ranches in the area. 

The principal highways of Guatemala are in the southern and central parts of the country. The Inter-American Highway extends from 

Ayutla at the Mexican border eastward to Escuintla; another highway 

leads from Tapachula through Quetzaltenango to Guatemala City and 

thence eastward to El Salvador. Connecting roads link these highways in several places. Secondary roads extend into the highlands 

from several points on the Inter-American Highway: one runs northward from Guatemala City to Semococh and another from Guatemala. 

City to Rio Hondo, paralleling the railroad; another extends from 

Quetzaltenango to Tojquiaj ; and still another from Los Encuentros 

to Cunen. 

Work on the Inter-American Highway was not carried on in Guatemala between 1941 and 1945. A new route which leads from the 

State of Chiapas in Mexico through Huehuetenango and thence to 

Guatemala City is now contemplated for this highway. Aerovias de 

Guatemala operates frequent air service to Quetzaltenango, Cohan, 

and Flores. 

EL SALVADOR 

There are two railway lines in El Salvador. One, the El Salvador 

Division of the International Railways of Central America, enters El 
GEOGRAPHY 11 

Salvador near Metapan, runs southeastward to San Salvador, and 

-continues across the entire length of the country to the por·t of Cutuco 

on the Golfo de Fonseca. The other railroad, owned by the Salvador 

Railway Company, Ltd., extends frmn San Salvador southwestward 

to the port of Acajutla and northwestward to Santa Ana. Both 

,railroads are narrow gage. 

· The Inter-American Highway passes through El Salvador, extending from San Cristobal on the Guatemalan border, through San Salvador to Cutuco, and thence to Goascoran, Honduras. Over part of 

-the distance the highway parallels the railroads. Secondary roads 

1passable most of the year extend southward and northward from the 

main highway, giving El Salvador the best-developed road network 

·of all the Central American countries. 

HONDURAS 

·The railroads of Honduras are all on the north coast; they run along 

-the coastal plain and up into the broad valleys. Three principal railroad systems cover the area. The National Railway, operated by the 

·Tela Railroad Co., runs between Puerto Cortes on the Atlantic coast 

to Potrerillos, a distance of 59 miles. The Tela Railroad Co. also 

-operates connecting lines to Tela and Ulua, which serve the .banana 

plantations of the United Fruit Co. on the north coast of Honduras. 

'The railroad of the Standard Fruit and Steamship Co. extends from 

the port of La Ceiba eastward and westward along the coast, then 

jnland to connect with lines of the Trujillo Roalroad, a subsidiary of 

·the United Fruit Co. The Trujillo Railroad extends from the port of 

·Trujillo up the Rio Agmin to Olanchito; in 1942 a part of the railroad 

'Was torn up. 

The highways of Honduras cover only the central and southern 

. parts of the country, but they connect with the railroad at Potrerillos 

to permit travel to the notth·coastal area. A few short roads ·extend 

~out from the railroads on the north coast. 

The Inter-American Highway enters Honduras near Goascoran on 

-the El Salvador border and continues eastward, entering Nicaragua 

at El Pino. From San Lorenzo, on the Bahia San Lorenzo, a road ex-

;tends northward to Tegucigalpa, crossing the Inter-American High-

·way near N acaome. From Tegucigalpa a road extends northward 

through Comayagua, Potrerillos, and San Pedros Sula to El Paraiso; 

.a road extends westward from San Pedro Sula to Macuelizo. 

NICARAGUA 

Transportation facilities are best developed in the western part of 

Nicaragua because both industry and population are concentrated in 

that area. The National or Pacific Railroad extends from the port 

<Of Corinto through Managua to Granada on Lago de Nicaragua. 
12 MINERAL DEPOSITS OF CENTRAL AMERICA 

Branch lines extend to Jinotepe, Puerto Morazan, and El Sauce. Another 8ection of the railroad, separated from the main line, runs be .. 

tween San Jorge and San Juan del Sur, a port on the Pacific Ocean. 

The Inter-American Highway enters Nicaragua at El Pino, from 

which it extends southeastward to Managua and thence to the Costa 

Rican border at Pefia Blanca. Secondary roads extend eastward from 

Managua to La Libertad, and othe:rs from several points on the highway into western Nicaragua. 

The eastern part of Nicaragua can be reached only by air or by 

trails from the western part. The TACA Co (Transportes Aereas 

Centroamericanos) operates frequent flights from Managua to eastern 

Nicaragua and northern ports. Shallow-draft boats can travel from 

the Caribbean Sea up the principal riversas much as 50 milu;. 

COSTA RICA 

Most of Costa Rica's population is concentrated on the central plateau; therefore, transportation facilities are best there. Two railroads 

extend to San Jose, the capi·tal-the Northern Railway, which runs 

from Puerto Limon on the Caribbean coast, and the Pacific Railway,. 

which runs from Puntarenas on the Golfo de Nicoya. In ad~ition, a 

railway network owned by the United Fruit Co. covers part of the 

Atlantic coastal plain to the northwest and south of Puerto Limonr 

On the Pacific coast, two short railroads serve ban81na. plantati()BS in 

the Puerto Quepos and Golfito areas. The principal routes of trans~ 

portation are in a belt extending east and west across the country. 

The highway system also is best developed on the central plateau~ 

Roads radiate from San Jose eastward as far as Guacima and westward to Puntarenas. The Inter-American Highway extends into) 

Costa Rica from Nicaragua to Las Caiias, but the section into San Jose·: 

is not complete. From San Jose the highway extends to San Isidro .. 

A gap still exists between San Isidro and the Panama border. The· 

Peninsula de Nicoya and parts of northwestern Costa Rico are served 

by the TACA Co. The only airport in eastern Costa Rica is at Puerto 

Limon. 

PANAMA. AND THE CANAL ZONE 

The transportation routes of Panama are best developed in the Canal 

Zone, which bisects the country, and in the southwestern coastal area~ 

Three railroads are operated in Panama. The line of the Panama 

Railroad Company parallels the Panama Canal from Col.6n to Panama 

and crosses the isthmus. Another, the Ferrocarril Nacional de Chiriqui (Chiriqui National Railroad), extends from Port Armuelles: 

through David to Boquete and Pedregal in central western Panama. 

The third, the United Fruit Company Railway, extends from Almirante on Laguna de Chiriqui to Suretka in Costa Rica. 
GEOLOGY 13 

Most of the Inter-American Highway in Panama is passable the 

year around, but a section from the Panama border to San Isidro, 

Costa Rica, is not yet complete. The highway has been constructed 

only to Chepo, east of Panama. A transisthmian highway roughly 

parallels the canal from Panama to Colon. 

The Chiriqui Land Company Railway from Puerto Armuelles to 

Progreso connects with the lines of the Chiriqui National Railroad. 

In the province of Colon, two short railroad spurs are used for hauling 

bananas. 

GEOLOGY 

The geology of Central America is still far from being completely 

known. In much of the region widely separated traverses have given 

only a glimpse of the complex stratigraphy and structure, and vast 

areas have never been visited by a geologist. Central America offers a promising field for geologic study, for, contrary to the general 

concept of tropical jungle being everywhere, many of the highland 

and savanna areas have exposures comparable to those in our Western 

United States. Travel in Central America is still difficult in most 

places, and due care should be taken to plan for traveling in the proper 

season. 

The geologic map of Central America (pl. 1) shows the geology 

as based on the best information now available. The map includes 

data obtained from many reports, which vary widely in the scale of 

their maps and the fullness of their descriptions. 

PREVIOUS WORK 

Dollfus and Montserrat (1868, p. 270f) were the first geologists to 

visit Central America who made any attempt to map the rocks and 

to describe them systematically. Their map, although generalized, 

gives a good idea of the stratigraphic sequence in Guatemala and 

El Salvador. 

In the 1880's the noted German geologist and volcanologist Karl 

Sapper began the work that laid the foundation of the study of Central ~erican geology. Sapper made a series of trips through all 

parts of Central America, gathering geologic data. In 1899 he published the first of his summary works dealing with the geology of 

northern Central America, which included a geologic map on a scale 

of 1 : 1,100,000. His summary of the geology of southern Central 

America followed later (Sapper, 1906). Subsequent work by Sapper 

and others modified in many details the maps accompanying these reports, and in 1937 Sapper published a revised account of the geology 

of Central America. Miillerried ( 1942a, 1944) has also made many 

valuable contributivns to the geology of northern Central America. 
14 MINERAL DEPOSITS OF CENTRAL AMERICA 

Many other geologists have contributed to our knowledge of the 

geology of Central America, although little regional mapping has 

been done. Oil companies interested in petroleum in Central America 

have done detailed work in some areas, but most of this work is not 

yet available for publication. 

STRATIGRAPHY OF NORTHERN CENTRAL AMERICA 

PRE-PERMIAN ROCKS 

In Guatemala, Honduras, and Nicaragua, metamorphic rocks are 

widespread; they include gneisses, schists, quartzites, marbles, and 

phyllites that form the cores of the principal ranges. The degree of 

metamorphism varies from place to place, and there is probably a 

great time interval between the youngest and oldest rocks; however, 

they are grouped in three units in plate 1. Sapper (1937, p. 2'3), 

Miillerried (1942b, p. 472), and the writers consider that these metamorphic rocks may include some pre-Cambrian formations and that 

the youngest may well be of late Paleozoic age. All that has thus far 

been proved is that the metamorphic rocks in some pl:;tces underlie 

fossiliferous Permian ( ~) strata and are therefore pre-Permian ( Schuchert, 1935, p. 342) .· 

The metamorphic rocks crop out in· a belt extending eastward from 

Chiapas, in Mexico, through Huehuetenango in western Guatemala, 

and make up the Sierra de Chuacus, the Sierra de las Minas, the 

Sierra del Espiritu Santo, and the coastal ranges of northern Honduras and Nicaragua. These rocks consist of a great thickness of 

garnetiferous and micaceous gneiss, mica schist, hornblende schist, 

andalusite and garnet schist, quartzite, and marble. In places the 

metamorphic gneiss grades into intrusive granite gneiss and granite. 

Metamorphic rocks of lower grade, such as phyllite, quartzite, schist, 

and marble, are also found within this belt, especially in Honduras 

and Nicaragua; some of these rocks may belong to a younger series. 

They may be of late Paleozoic or even early Mesozoic age, and may 

have been metamorphosed during orogenic movements and by granitic 

intrusions accompanying the orogenies. 

Miillerr.ied ( 1942b, p. 4 7 4) suggests that Central America had a 

geologic history similar to that of northern Mexico and the southwestern United States, where sedimentary rocks of early Paleozoic age 

were metamorphosed during orogenic movements of middle and late 

Paleozoic time. This may well be true, but only detailed geologic 

work will solve the many problems that these rocks present. 

ROCKS OF PALEOZOIC AGE 

Rocks of Paleozoic age are widespread in northern Central America and form a belt as much as 22 miles wide adjoining the metamorphic belt on the north in Guatemala and extending eastward to Puerto 

Barrios. In British Honduras, lithologically similar strata make up 
GEOLOGY 15 

the Maya Mountains, and in northern Honduras and Nicaragua they 

crop out in the coastal ranges. · 

PERMIAN SYSTEM 

In Guatemala the strata of Paleozoic age that have been dated consist of two formations of Permian age: the Santa Rosa formation of 

Permian( n age and overlying limestone and dolomite beds which we 

propose calling the Chochallimestone. 

SANTA ROSA FORMATION 

Santa Rosa formation was the name applied by Dollfus and Montserrat (1868, p. 270f) to strata exposed near the village of Santa Rosa 

in the Departamento de Alta Vera paz, Guatemala. The formation· 

consists of interbedded sandstone, shale, limestone, puddingstone, and 

marl. Its upper beds grade into the overlying limestone, which was 

referred to by Sapper (1899, p. 64) as the Carbonkalk. 

The Santa Rosa formation is deeply weathered ·at the type :J~wlity,. 

and the base is not exposed. However, near Sinanja in Alta Verapaz, 

according to Sapper (1937, p. 24) the Santa Rosa formation rests unconformably on the folded pre~ Permian(~) rocks, and its lowest members contain fragments of these rocks. It is likely that the basal beds 

of the Santa Rosa formation rest unconformably everywhere on the 

pre-Permian ( ~) rocks. 

Sapper described the basal part of the Santa Rosa formation as consisting of coarse clastic rocks, which become progressively finer upward and are interbedded with increasing amounts of sha:ly limestone. 

The formation is exposed almost continuously westward into Mexico. 

The thickness of the section in Chiapas, Mexico, is reported to be 

1,000-3,300 feet (Miillerried, 1942b, p. 472; Thompson and Miller,. 

1944). Thompson and Miller measured several sections in Chiapas 

and made a tentative correlation with part of the Santa Rosa formation. They called the lower clastic beds the Santa Rosa ( ~) formation 

-and named the upper beds the Grupera, the La V ainilla, and the 

Paseo Hondo formations. According to them, the Grupera formation 

consists of 400 feet of interbedded shale and sandstone which contains 

many invertebrate fossils. They correlated these beds with the Hueco 

limestone of west Texas of W olfcamp age. The Grupera formation 

is overlain by the La Vainilla limestone, about 300 feet thick, wh~ch 

contains Sahwage!f'liJna figueroai and appears to be youngerthanupper 

Wolfcamp, but pre-Leonard (Thompson and Miller, 1942). The La 

Vainilla limestone is overlain by 475 feet of interbedded limestone 

and shale which Thompson and Miller named the Paseo Hondo formation. Fusulinids collected from these rocks are correlated with 

those of the Leonard formation of west Texas. 

In the Chiantla-San Sebastian area in the Sierra de los Cuchumatanes in western Guatemala, which was mapped by Roberts (pl. 9), 
16 MINERAL DEPOSITS OF CENTRAL AMERICA 

no complete section of the Santa Rosa formation is exposed, but a lower 

unit of interbedded sandstone, shale, and conglomerate and an upper 

unit of red, brown, gray, and black shale with interbedded shaly limestone, sandstone, and dolomite were mapped. The lower unit is exposed on:ly in a fault block at the foot of the range, but a few miles to 

the west it is several thousand feet thick. The upper unit, which is well 

exposed on the middle slopes of the range, has a thickness of about 

a thousand feet. The upper 400 feet of the section is composed mainly 

of interbedded shale, limestone, and shaly sandstone. The limestone 

members range in thickness from a :few :feet to more than 75 :feet; they 

are lenticular and pinch and swell along the strike. No attempt was 

made to subdivide these rocks, but units equivalent to the Grupera 

and La Vainilla :formations o:f Miller and Thompson (1944, p. 481-

504) probably occur there. 

Fusulinids collected :from the upper part o:f the Santa Rosa :formation near Chochal (pl. 9) were determined by Lloyd G. Henbest to 

be of Permian ( ~) to middle Permian age (W olfcamp and Leonard). 

The~ooJ.lections were reported "On as follows : 

Specimens from the upper part of the Santa Rosa formation, near Ohoc1wl 

44-C-47 (from Torlon mine). 

Sohwagetrina or possibly Parafusu'Uina sp. (material insufficient for 

determination. but there are indications that Schwagerina gr'llr 

per.aensis Thompson and Miller is represented) 

Grupera formation is suggested, but the evidence is very meager. 

Early to middle Permian age is rather definitely indicated. 

~C-45 (half mile iwrthwest of peak, altitude 7,442 feet, southwest of Tor16n 

mine). · . . 

Schwagerinid fragment. 

Material insufficient to determine other than that it indicates Permian 

age. 

The limestone and shale beds in the upper part o:f the Santa Rosa 

formation also contain many poorly preserved larger invertebrate 

fossils. These were studied by J. E. Smedley and :found to contain 

productid, spiriferid, derbyid, and chonetid brachiopods, as well as' 

an avicular pectinid and other pelecypods, corals, gastropods, and 

bryozoans. For the most part specific detenninations of these fossils 

were not possible, but Smedley stated that the fauna could well be of 

Permian age. 

CHOCHAL LIMESTONE 

The limestone units that Sapper (1899, p. 64) referred to as the 

Carbonkalk were never precisely defined. He apparently used this 

term to include all the units between the Santa Rosa formation ~nd 

the Todos Santos formation. In places the boundary between the 

Santa Rosa :formation and the overlyingJimestone is sharp, but generally these limestone units interfinger with the upper shales of 'the 

Santa Rosa formation, and the contact is gradational. 
GEOLOGY 17 

When the Chiantla-San Sebastian area was mapped (pl. 9) the 

massive, cliff-forming limestone units that form the upper slopes of 

the range were distinguished from the interbedded limestone and 

·shale units of the middle slopes. Fusulinid collections from these 

upper limestone beds near Chochal have been studied by Henbest, who 

<determined them to he of Leonard and possibly Word age. The lime-

~stone units would therefore be in part correlative with the La V ainilla 

:and Paseo Hondo formations of Miller and Thompson, but the 

fusulinids indicate that the units also contain beds younger than the 

Paseo Hondo formation. As the limestone at Choohal is a mappable 

unit and is not specifically correlative with the Paseo Hondo 

formation, it is proposed that it be named the Chochallimestone. 

The section selected as typical is llh miles north of the La Esperanza 

mine and 2112 miles east of Chochal, where the limestone is well exposed in steep cliffs. This section includes the following units : 

Section of the OhochaZ Zimestone, 1lh miZes north of the La Jilsperanza mine 

and 2lh miles east of OhochaZ 

Erosion surface. 

Thiolmestt 

(feet) 

Limestone, gray, thin to medium thickness beds; contains dolomite, shale, 

and shaly limestone beds. ~'orms craggy outcrops and steep cliffs___ 350 

Limestone, gray, cliff-forming---------------------------------------- 95 

Limestone, gray, sb.aly---------------------------------------------- 30 

Limestone, thin to medium thickness beds, with shale pertings...:..________ 50 

Lim~tone and dolomit~ gray; shale units with chert nodules and abundant crinoid stems, braehiopods, bryozoans, and fusulinids---------- 75 

600 

This section is incomplete; higher units are present outside the 

mapped area, and it is estimated that the formation may be as much 

as 2,000 feet thick. Fusulinids collected :from the lower part of this 

section were studied by Henbest and reported on as follows: 

Specimens from the Ohockal limestone, 2% mile1 each oj Ohacl5al 

44-C-37 (two and a half miles northeast of Chochal, at an altitude of about 

11,000 feet). 

Eoverbeekina americana 

tParafusuUna au&tra'Us 

Preservation of the fossils is poor. Correlation with the Paseo Hondo 

of Thompson is indicated. 

44-Q-11 (a mile northwest of Chochal at an altitude of about 10,500 feet). 

ParafusuUna sp. (large form 16-19 mm long, with phrenotheca closely 

coiled} 

Word age, Permian seems represented. 

Collections from other localities in the Chochal limestone were obtained in the middle slopes of the range. On the basis of very small 

and more or less metamorphosed samples, Henbest gives the following report: 
, 

18 MINERAL DEPOSITS OF CENTRAL AMERICA 

Specimens from the Ohochal limestone, middle· Blopes of the Sierra de los 

OuchumataneB 

44-C-30 (Las Manzanas, altitude 8,400 feet, about three-fourths mile northwest: 

of houses). 

Endothyra sp. 

Eoverbeekina americana Thompson and Miller 

Schwauerina sp. or Parafusulina sp. 

Parafusulina sp. 

Apparently correlative with the Paseo Hondo formation. Middle• 

Permian age is indicated rather definitely but the possibility of Hueco 

early Permian(?) age, cannot be ruled out. 

44-C-31 (Las Manzanas, altitude 8,500 feet, about a mile northwest of houses) .. 

Eoverbeekina americana Thompson and Miller 

Parafusulina sp. (possibly Schwauerina sp.) 

fParafusulina australis Thompson and Miller 

Apparently correlative with the Paseo Hondo formation. Middle Permian indicated but might possibly be of Hueco, early Permian ( ?) age~ 

44-C--33 (half-mile southwest of La Esperanza mine). 

Oornttapira sp. 

Endothyra sp. 

Eoverbeekina americana Thompson and Miller 

Schwagerinid or parafusulinid (not identifiable) 

Apparently same age as 44-C-30 and 44-C-31. 

44-C-78 (on trail at 8,100 feet, about a mile south of Las Manzanas). 

Parafuaulina sp. 

Specimens intensely distorted by rock :flow. Species appear to be as: 

young or younger than the Paseo Hondo formation and differ from any 

of the faunas discussed above. The great uncertainity of evidence must 

be emphasized. 

HU-266 (near trail about a mile southeast of Chochal). 

fParafusulina guatemalaensia Dunbar (material insufficient for a positive determination but appears to be within the limits of the species as· 

defined by Dunbar) 

Sponge spicules very abundant. Correlation with 44-C-11 is suggested. 

but must be regarded as very uncertain. With the material at hand it· 

could not be proved that this form does not belong to an earlier Permiall' 

species of Schwauerina. 

The Chochal limestone extends eastward from the type _area and 

forms prominent cliffs in the ranges near San Cristobal, Cohan, and· 

Panz6s. Dunbar (1939, p. 344-348) redescribed three lots of fusulinids collected by Sapper from-limestone in north-central Guatemala 

near Cohan. Two species were recogniz~d : Parafusuli'fi!Z sq-pperi fr~.­

Trece Aguas and Panzal was determined to be middle :Permian, 

Leonard, or possibly Word in age, and P arafus~tl-ina guatemalaensis· 

from Purulha was determined to be of Leonard age. The limestone 

that yielded these collections is lithologically similar ~o the Chochal 

limestone and is probably correlative. 

Strata of Paleozoic age are reported in other parts of Central 

America but have not been studied in detail. In northwestern Guate~ 

mala, Termer (1931, p. 244), found plant remains in dark shales that: 
GEOLOGY 19 

were as8igned to the Permian. These beds may be a f~cies of the Santa 

Rosa formation. Strata of Paleozoic age. that extend into northern 

Honduras and western Nicaragua have been described by Sapper 

(1937, p. 24, 25), Mierisch (1895, p. 56_.:57) and others. The strata 

·consist of interbedded slate, phyllite, limestone, quartzite, and quartzite conglomerate. These rocks may in part be equivalent to the Santa 

Rosa formation and Permian limestone of. Guatemala, but m~y well 

include older strata •. The fossils. found thus .far in these- rocks .have 

·been-too poorly preserved for: specific determination. 

PR.&CRETACEOUS ROCKS 

Because of the uncertainty of the age of the. metamorphic rocks that 

underlie the Metapan formation in eastern Honduras and Nicaragua, 

these rocks have been labeled pK on plate i~ signifying only that they 

are pre-Cretaceous in age. They probably include rocks of Jurassic, 

Triassic, and Paleozoic ages, and may even include rocks of pre-Cambrian age as well. ROQK~ OF, MESOZOIC AGE 

Rocks of Mesozoic age underlie much of the northern part of Central 

America, especially north of the belt of rocks of Paleozoic and prePaleozoic age in Guatemala and Honduras. The sections of Mesozoic 

age generally include basal redbeds, overlain by interbedded limestone, 

dolomite, and shale. The stratigraphic succe.ssion has been ably ~UID,­

marized by Schuchert (1935, p. 237) and Imlay. (1943, p .. 1499, 1501, 

and 1505; 1944, p.1113-1120). 

The Paleozoic era ended in Central America with an o:r:ogeny during 

which the rocks of Paleozoic age and older rocks were folded and cut 

by granite and serpentine intrusive bodies. The earliest Mesozoic 

formations are terrestrial deposits composed mainly of coarse clastic 

rocks, but they also locally interfinger with beds of shale, marl, and 

limestone that may have been deposited in marine or lacustrine environments. On plate 1 the older Mesozoic rocks have been assigned 

to the El Plan (Tegucigalpa), Todos Santos, and Metapan formations. 

Most writers have correlated these formations because they are lithologically similar, but they are not equivalent in age and were probably 

deposited in separate basins. 

One of the confusing problems in Central American geology is the 

terminology used for the redbeds and associated rocks in central Honduras. The Tegucigalpa formation is one of the formations that has 

long been involved in controversy. Near the Rosario mine at San 

Juancito, plant remains collected from shales were regarded by Newberry (1888, p. 324--351) to be of Rhaetic (Late Triassic) age but were 

later redetermined by Knowlton (1918, p. 607) to be of Early and 

Middle Jurassic age. Sapper (1937, p. 27} referred to these plant-
20 MINERAL DEPOSITS OF CENTRAL AMERICA 

bearing shales as the Tegucigalpa formation and believed that they 

might be in part equivalent to the Meta pan :formation. Weaver 

(Schuchart, 1935, p. 36) described the Tegucigalpa formation as. consisting of about 800 feet of dark-brown sandstone. and dark .. gray to 

black carbonaceous shale and argillite; he stressed the fact that these 

rocks were more indurated than the strata of the Metapan formation .. 

As far as the writers know ther;e are no dark shale and sandstone beds 

near Tegucigalpa that are correlative with the Jurassic rocks near San 

Juancito. To avoid the confusion caused by the use of the term Tegucigalpa formation, Carpenter (1954, p. 25) proposed that the plantbearing beds at San ,J uancito be named the El Plan formation. He 

described the formation as consisting of alternating members of darkgray shale and siltstone with some argillaceous sandstone and pebbly 

conglomerate. The thickness shown on Carpenter's figure 2 is about 

3,000feet. · 

Carpenter (1954, p. 27) also mapped the geology of the Rosario 

mine area in central Honduras and divided the Cretaceous rocks 

there into five :formations. The oldest, the Cantarranas :formation, 

consists of a lower member of limestone and shale 132 feet thick; a 

middle member of calcareous shale, sandstone, and limestone, 345 :feet 

thick; and an upper member of limestone, calcareous siltstone, and 

sandstone, 125 :feet thick. Fossils :found in the upper member include 

Ostrea, Gryphaea cf. G. corrugata, Pholadomye, and Orassatellitesl; 

the formation was considered to be in part equivalent in age to the 

Metapan formation in the northern part of the Departamento de 

Tegucigalpa. The next younger :formation was named the Colonia 

andesitic tuffs and breccias. Near the Rosario mine these rooks rest 

unconformably on the Triassic El Plan :formation and are about 3,000 

feet thick. The Colonia formation interfingers laterally with the 

Crucero tuffaceous dacite flows, which total more than 400 :feet in 

thickness. The next younger Cretaceous :formation is the Plancitos 

formation, which consists of medium- to coarse-grained grit, sandstone, siltstone, and shale, and is about 1,900 feet. thick. Inasmuch 

as these Cretaceous units have not been mapped separately outside of 

the Rosario mine area, they are assigned to the Metapan :formation 

on plate 1. 

The Todos Santos :formation, named by Sapper (1899, p. 65; Miillerried, 1942b, p. 474-475) after a village in the Departamento de Huehuetenango, Guatemala, comprises about 1,200 :feet of interbedded 

reddish-brown sandstone, shale, and conglomerate; in places green 

shales and gray limy shales are intercalated, and thin limestone lenses 

are present locally. The Todos Santos :formation rests unconformably on :folded and metamorphosed rocks of the Santa Rosa and ~lder 

:formations and is over lain by limestone of Albian to Cenomanian age 
GEOLOGY 21 

(late Early Cretaeeous to early Late Cretaceous) according to MUller-· 

ried (1942b, p. 476). 

At Todos Santos, Miillerreid found plant remains of Early a.nd 

Middle Jurassic age in the lower part of the Todos Santos formation, 

and· he considered it likely that the basal part of the formation might 

be Late Triassic, but, as the Todos Santos strata overlap an older land 

mass, the basal-beds in one place may differ in age from those in another. In Chiapas the upper Todos Santos strata have yiel4ed 

N eocomian (Lower Cretaceous) fossils. On plate 1 the Todos Santos 

formation is designated as Jurassic and Cretaceous. 

Near San Miguel Acatan the Todos Santos formation is overlapped 

by limestone and dolomite probably of Early Cretaceous age. The 

overlap is an angular unconformity and shows that the uplift of the 

Sierra de los Cuchumatanes had continued during the Late Jurassic· 

and Early Cretaceous. The Todos Santos formation in this area is 

probably not more than 400 feet thick, and west of San Miguel it is 

entirely absent in places, either because it was not deposited or because 

it was eroded before the Cretaceous limestone was deposited. 

At San Mateo Ixtatan, Guatemala, and in Estado de Chiapas, 

Mexico (Sapper, 1937, p. 27), the upper Todos Santos strata are marl, 

shale, and sandstone, and include interbedded gypsiferous a.nd saltbearing strata, indicating a change northward from terrestrial to 

marine conditions of deposition. In Chiapas, beds of comparable age 

(Imlay, 1944, p. 1118) contain marine fossils that have been listed 

by Miillerried ( 1936, p. 36). 

In eastern Guatemala, El Salvador, and Honduras, redbeds lithologically similar to the Todos Sandos strata have been named the 

1\fetapan formation by Sapper (1899, p. 65; 1937, p. 27). The type 

locality is at Metapan, in northwestern El Salvador. No section has 

been measured there, but the strata are estimated by the present writers 

to be 1,500 feet or more in aggregate thickness. Where the base of 

the section is exposed near Concepcion in nearby Guatemala, the 

Meta pan formation rests on contorted schist that has been assigned 'to 

the Paleozoic. (See pl. 8.) The lower part of the Metapan formation inchides interbedded sandstone, conglomerate, shale, volcanic 

tuff, and marly beds. The beds are mostly dark red, but some are 

purple, dark green, and yellow and brown. The coarser members show 

poor sorting and were evidently derived from nearby sources. The 

upper part of the formation is composed of interbedded red, yellow, 

and gray shales with thin limy shale and limestone beds; the highest 

member is a cliff-forming limestone 100 feet or more thick which is 

exposed east of Metapan and at El Sillon near Concepcion. The 

limestone contains poorly preserved fossils of indeterminate age. 

The Metapan formation is not highly fossiliferous, but red shale 
MINERAL DEPOSITS OF CENTRAL AMERICA 

beds associated with volcanic tuff near Metapan yielded fossils determined by Ralph Imlay to be Ewogyra arietina Roemer of late 

-Com~nche (early Late Cretaceous) age. 

In eastern Guatemala and western Honduras Sapper (1899, P: 65) 

described limestone that rests concordantly on shale, sandstone, and 

conglomerate that he called the Metapan beds. The limestones were 

differentiated by Sapper (1899, map; 1937, table 6). He considered 

. th& limestone to he. of Cretaceous age. but did not collect diagnostic 

f<>ssils from it. Subsequently Miillerried ( 1942a, p. 125) and others 

established a middle Cretaceous age (now known to be early Late 

·Cretaceous) for the limestone units that overlie the redbeds of the 

Metapan formation in eastern Guatemala and Honduras. The limestone is therefore only slightly younger than the Metapan formation. 

On plate 1 the limestone is included with the Metapan formation near 

· Metapan, but throughout central Honduras and Nicaragua it is shown 

separately. 

· Weaver (1942, p. 179-180) proposed the name ·Esquias formation 

for the upper part of the· sequence of· interbedded limestone, conglomerate, sandstone, and shale that overlie the Metapan formation 

in central Honduras. Fossils that Weaver found in the Esquias 

formation were poorly preserved and not diagnostic, so he could not 

determine how much of Cretaceous time was represented by these beds. 

This formation is therefore not differentiated on plate 1 but is grouped 

'with the Upper Cretaceous limestone unit. It seems likely that a considerable thickness of limestone and shale may lie between the Meta pan 

formation and· the Esqufas formation. Further study of the sections 

·in central Honduras will be required before the stratigraphic successions can be determined. 

Although the Todos Santos formation and the Metapan formation 

are similar in lithologic composition, they are not of the same age, 

as suggested by several authors (Miillerried, 1942a, p. 129; Sapper, 

1937, p. 26, 27, 109), for the fossils\collected in the Todos Santos fOrmation are Early Cretaceous (Neocomian) or older, and those collected 

in the Metapan formation are early Late Cretaceous. It is possible, 

however, that older beds may be found in the Metapan formation that 

are equivalent in age to the beds in the upper part of the Todos Santos 

formation. 

In northwestern Guatemala the Todos Santos formation is overlain 

by limestone, which Termer (1932, p. 247; 1936, p. 142) named the 

Ixcoy formation and correlated with the Cohan limestone of Sapper 

(1899, p. 65; 1937, p. 28-29). Termer found no diagnostic fossils in 

the Ixcoy but thought it might be correlative with middle to Upper 

Cretaceous limestone in Estado de Chiapas, Mexico. The Ixcoy formation comprises over 2,000 feet of interbedded limestone and 
GEOLOGY 23 

dolomite and is the host rock of the lead-zinc deposits of the San 

Miguel district. For the most part the beds are thick to massive and 

light to dark gray. In many places the formation contains thick 

intraformational conglomerates and breccias, possibly formed during 

periods of minor crustal movements. 

In northwestern Guatemala (pl. 1}, the Ixcoy formation is shown 

by Termer to be in fault contact with the Cohan formation, which 

contains late Early Cretaceous fossils in its lower beds (Miillerreid, 

1942a, p. 134, 136). The Cohan formation was estimated to be more 

than 1,000 feet thick. North of Cohan, the Cohan formation is overlain by Upper Cretaceous limestone similar to Upper Cretaceous beds 

in Chiapas. 

Termer assigned all the limestone of the Sierra de los Cuchumatanes 

to the Ixcoy formation, but inasmuch as Sapper (1899, p. 67) mapped 

two areas of Sepur rocks (of Eocene age) at the crest of the range, 

it seems certain that the Upper Cretaceous· is present there also, beneath the Sepur beds. The higher beds in the range are composed 

of massive craggy-weathering limestone with thick-bedded and thinbedded members, which are unlike the porous coarse-grained breccia 

and conglomerate that occur in the Ixcoy formation. The upper limestone is dense and fine grained and ranges from light gray to brownish 

gray. These beds may be 500 feet or more in thickness in this.area. 

TERTIARY SYSTEM 

The Tertiary rocks of northern Central America comprise marine 

and continental formations that range in age from Eocene to Pliocene. 

The marine beds are well exposed in northern Guatemala, where they 

overlap the Cretaceous beds. 

No recent comprehensive accounts of the Tertiary stratigraphy o-f 

northern Central America are available, but Schuchert (1935, p. 332, 

390, 556-564) and Sapper (1937, p. 31-32} summarize published 

information up to 1937. . 

The oldest Tertiary rocks in Guatemala are in the Sepur formation, 

of Eocene age, exposed in the northern part of the Republic (Sapper, 

1937, p. 31}. ·These beds consist chiefly of red sandstone, conglomerate, and shale, with local interbedded limestone and marl members. 

Near Cahabon, beds of terrestrial conglomerate and sandstone predominate, but to the north and west the coarse facies grades into red 

and yellow marine clay and marl that are interbedded with yellow 

sandstone, conglomerate, and limestone. The conglomerate beds are 

composed of pebbles of andesitic volcanic rocks, limestone, schist, 

and quartzite. Judging from the increase in coarseness of the Sepur 

strata southward, they were probably derived from highland areas 

in central and southern Guatemala and western Honduras. 

388364-57-3 
24 MINERAL DEPOSITS OF CENTRAL AMERICA 

· Wadell (1938, p. 341) has described the basal part of the Tertiary 

section in the· southern part of the Departamento de Peten, Guatemala, 

as consisting of sandstone and sandy marl of the Sepur formation, 

resting on fossiliferous Upper Cretaceous limestone. To the north the 

Cretaceous rocks are overlapped by Upper:Eocene( ~),Oligocene, and 

Miocene rocks, largely limestone, marl, gypsum, and limestone· breccia 

and conglomerate. 

·Carpenter (1954, p. 28) reports that red shale, siltstone, and sandstone estimated to be 10,000 feet thick make up the southern third of 

the Sierra San J liancito north of Tegucigalpa. He· named this sequen·ce the Valle de Angeles formation and thought that it might be 

Late Cretaceous or early Tertiary in age. This formation is overlain 

by younger pyroclastic and volcanic rocks. 

Woodring (1928, p. 67) mentions the occurrence of lower'Miocene 

molluscs inbeds exposed on the Rio Dulce iii north~astern Guatemala. 

Van den Bold (1946, p. 43-48, 52--57, 126) studied ostracoda collected 

from Tertiary strata in Guatemala, British Honduras, and Cuba by 

geologists of the Bataafsche Petroleum·Maatschappij. ·He found that 

some of the ostracodes resembled those reported from beds in the 

Southern United States. Van den Bold lists ostracodes and Foraminifera of Paleocene, early ·and middle Eoce~e, and 'Miocene ages 

from Guatemala and British Honduras. 

Flores, who carried out field· studies in northern British Honduras 

during 1950-51 (1952, p. 404-413), found that Upper Cretaceous, 

"Paleocene-lower Eocene," middle Eocene, and "Mio-Pleistocene" 

sedimentary rocks were present there. The Upper Cretaceous rocks 

include limestone, dolomitic limestone, dolomite, and a thin sandstone 

unit at the base of the exposed section. The "Paleocene-lower Eocene" 

rocks are limestone and dolomitic limestone which in places contain 

secondary black chert and a few bentonitic layers. The middle Eocene 

limestone is dense, commonly fragmented, and contains large chert 

inclusions. The "Mio-Pleistocene rocks" that overlie these formations 

include bentonitic clays with gypsum veins and poorly consolidated 

sands overlain by white sandy marls .. No fossils of Oligocene age 

were identified, and Flores considers that the Oligocene was a period 

of general emergence in this area. 

QUATERNARY SYSTEM 

Quaternary deposits underlie large areas in northern Central 

America (pl. 1). The wide Pacific coastal plain is composed of interbedded gravels and sands derived principally from ·the volcanic upland 

areas, and most large valleys are floored with alluvium (Sapper, 1937, 

p. 36). The belt of Quaternary deposits along the Atlantic coast is 

narrower, and marine terraces are found in some places. In British 
GEOLOGY 25 

Honduras and Honduras, quartzose sands underlie savannas along 

the coast; in part these sands.are Pliocene, but they also include ~Qu~t­

. ernary beds (Sapper, 1937, p. 84). 

In Guatemala, Honduras, and El Salvador, pyroclastic and volcanic 

rDcks of Quaternary .age .are widespread in the v.pland and Pacific 

coastaLareas and represent the continuation of volcanicactivity that 

b~gan in the Tertiary. Some of the volcanoes. are st.iH active, and 

ash falls have contributed large volumes of material to the so~lsand 

recent ,deposits .. (See Sapper, 1937, p. 10-22,: for. a detailed description (i)f .... volcanic activity in Central America .. ) 

IGNEOUS .ROCKS 

INTRUSIVE ROCKS 

Intrusive. rocks form a considerable. area w:ith:i,n the belt of prePermian metamorphic rocks that crosses northern Guatemala, }Ionduras, and Nicaragua. The intrusive rocks are cb.iefty gra~ite ~nd 

quartz monzonite .but include a little granodiorite and diorite, and 

serpentine forms two belts .that crop out discontinuous~y across Guatemala. . Smaller bodies, composed chiefly of . diorite, .granodiorite, 

quartz monzonite, and granite porphyry, are . scattered. over cent;J;al 

Guatemala, Honduras, and Nicaragua, south of ,the metamorphicrock.belt . 

. The granite and quartz monzonite are generally coars~ grained and 

light .to medium gray; biotite is their chief dark mineral. In. places 

these rocks are massive,. but for the most part they show a ;well-de:ijned 

foli.ation parallel to the structure of the enclos1ng rocks. Their Jtge 

is not known. Near San Miguel Acabin, Departamento de Huehuete· 

nango, Guatemala, unfoliated granite cuts shale of the Santa Rosa 

formation and is thus younger than Permian ( ~) ; the granite may have 

been intruded at the close of the Paleozoic. However, some of the 

foliated granite contributed pebbles and boulders to the conglomerate 

of the Santa Rosa formation, indicating that this granite is prePermian ( .~) . 

Bodies of serpentine are found north of the metamorphic belt from 

the . D!3partmento de Huehuetenango eastward nearly to Puerto 

Barrios; these are lenticular and are distributed along faults. ,Serpentine. also occurs east of Sal bin, in the southern part of the metamorphic belt. Serpentine intrusions form an important part of the 

central rap.ges of Guatemala. Two principal s,erpentine. belts h:;tve 

been Ulftpped (Sapper, 1899, p. 71; 1937, p. 10~) : one on the north 

of the metamorphic belt extends from San Sebast,ian eastwa:rd. to 

Salama, then from Panz6s nearly to Puerto Barrios ; the other, in the 

southern part of the.metamorphic belt, extends from Saltau.eastward, 

separating the metamorphic rocks into tw~ parts. Both belts follow 
26 MINERAL DEPOSITS OF CENTRAL AMERICA 

zones of strongly deformed rocks, probably along major faults, and 

therefore outline the principal structural features of Guatemala. 

The age of the serpentine is not definitely known, but it intrudes the 

Chochallimestone of Permian age and is overlain by the Todos Santos 

formation of Late Jurassic and Cretaceous age. The serpentine was 

therefore intruded sometime between the middle Permian and Late 

Jurassic. The serpentine intrudes the foliated granites but has been 

recrystallized locally by later intrusions. 

In central Guatemala, Honduras, Nicaragua, a~d El Salvador, small 

intrusions of diorite, granite porphyry, granodiorite, and quartz monzonite cut sedimentary rocks as young as Cretaceous. These intrusive 

rocks are entirely unfoliated and may be of Late Cretaceous or early 

Tertiary age. Typical intrusions may be found at Metapan in El 

Salvador and at Agalteca in Honduras. Dikes and sills of fine-grained 

and porphyritic rocks related to these intrusive bodies are widespread. 

Carpenter (1954, p. 29-31) has described the intrusive sequence at 

the Rosario mine, San J uancito, Honduras, in detail. He recognized 

hypersthene andesite, dacite, and granodiorite in the mine area. 

In southern Guatemala, southern Honduras, El Salvador, and 

Nicaragua, intrusive igneous rocks, chiefly andesitic in composition but 

including rhyolite and latite, form small irregular bodies, dikes, and 

sills. These rocks are related to the flows and pyroclastic rocks that 

make up the thick Tertiary cover, and some may have been the feeders 

for the flows and volcanic centers that were the source of the pyroclastic rocks. For the most part they are probably early Tertiary in 

age. VO~CANIC ROCKS 

Except for boulders of lava in Cretaceous conglomerate, the extrusive rocks known in northern Central America are of Tertiary and 

Quaternary age~ They are chiefly andesite, basalt, rhyolite, and 

latite, and occur as interbedded flows, generally interlayered with 

pyroclastic rocks. Most of the volcanic activity took place during 

Miocene and Pliocene time (Sapper, 1937, p. 40), when predominantly 

rhyolitic pyroclastic rocks and andesitic flows appear to have been 

extruded, but volcanism has continued into the Quaternary, and some 

volcanoes are still active. The early volcanoes, which gave rise to the 

bulk of the pyroclastic material and flows, have largely been eroded 

so that only their roots remain. The chain of later volcanic cones 

that borders the Pacific slope of Central America is built upon the 

eroded earlier volcanic plateau, much as Mount Rainier and Mount 

Baker in the Cascade Mountains of the State of Washington are built 

upon uplands composed of volcanic rocks. The later volcanoes bordering the Pacific in Central America were probably formed for the most 

part during late Pliocene and Quaternary time, for many of them 
GEOLOGY 27 

are very little eroded. In all, 61 principal volcanoes, and other smaller 

cones, are known to have been formed (see Sapper, 1927; also, other 

papers of his that describe Central American volcanoes). Activity 

still continues at several places, and Izalco in El Salvador and Santa 

Marfa in Guatemala are spectacularly active. The pyroclastic rocks 

and flows forming these cones are largely andesitic in composition, 

but some cones in eastern Guatemala are basaltic. The maximum 

thickness of the volcanic section of the underlying plateau is not 

known; in many places, however, it is more tban 3,000 feet thick. 

In western Honduras, in the Departmento de Gracias, part of the 

Tertiary sequence has been studied by Olson and McGrew {1941, p. 

1219-1244). The succession is ·600-1,000 feet thick and consists of 

clay, sandstone, volcanic ash, and conglomerate, and some marl. 

The beds contain lower I,liocene vertebrate fossils, among them 

Pliohippus hondurensis. 

Sayre and Taylor (1951, p. 170-185) have given a general account 

of the geology of El Salvador with emphasis on the geology of the 

valleys. They divided the volcanic rocks into 2 units_ of Tertiary age, 

3 units of Pleistocene age, and 1 unit of Recent age. The Tertiary 

rocks include early ( ~) Tertiary basic lavas and felsites with intercalated pyroclastic rocks and sediments, and late Tertiary pyroclastic 

deposits intercalated with andesitic and basaltic lava flows. The oldest Pleistocene unit consists of water-laid clay, silt, and sand that 

were deposited as lake beds; these rocks interfinger with pyroclastic 

rocks and lavas. Basaltic and andesitic lava flows and pyroclastic 

rocks that make up the volcanoes of the central highlands in El Salvador have been assigned to the middle unit of the Pleistocene (older 

Quaternary lavas and pyroclastic deposits). The youngest Pleistocene 

unit includes sands and gravels that form terraces on the Rio Lempa 

and its tributaries. The Recent volcanic rocks include basalt and 

andesite that were extrnded from vents on the flanks of the larger 

volcanoes and pyroclastic deposits derived from central eruptions. 

Sayre and Taylor (1951, p. 186-221) give also a detailed discussion 

of the ground-water conditions in each rock unit and discuss the 

ground-water hydrology in El Salvador, where studies were made of 

the water supplies of 30 towns and cities. 

During recent years Meyer-Abich has also carried on reconnaissance 

mapping of a considerable part of El Salvador and has published detailed maps of several areas ( 1952, 1953). The results of this work are 

incorporated in the geologic map (pl. 1). The Tertiary and Quaternary rocks have been grouped into units which include older Tertiary 

volcanic rocks (probably pre-Pliocene) that contain rhyolitic and 

andesitic flows and pyroclastic rocks in northern El Salvador; younger 

Tertiary andesitic lavas and pyroclastic rocks of probable Pliocene 

age; andesitic and basaltic lavas and pyroclastic rocks mainly of 
28 MINERAL DEPOSITS OF CENTRAL AMERICA 

Q.uaternary age which :form the chain o:f volcanoes that·extends northwestward through the country; lacustrine beds; tuff~ a:nd ash:deposits 

in some o:f the valleys; and= andesitic and· basaltic vol~anic rooks· .in 

some vol~anoes, such as Guazapa about 15'miles north of San Salvador, 

which are more deeply eroded than the youngest volcanoes· and may be 

o:fearly Pleistocene or· even Pliocene age. 

ST!RATIGBAPHY· OF SOUTHERN, CENTRAL AMERICA· 

Southern Central America, which comprises Nicaragua, ·costa Rica, 

and Panama, is connected with South America by the Panama-Costa 

Rica isthmus, which· is a submarine swell that is 200 miles wide at a 

depth o:f 6,000 :feet below sea level, and.100-130 1niles wide at a depth o:f 

600 :feet. The land width is 31-120 miles. The basement complex of 

the isthmus consists of Cretaceous ( ? ) and pre-Cretaceous igneous, 

metamorphic, pyroclastic, and sedimentary rocks. Marine :formations, 

largely clastic rocks, were deposited on these basement rocks beginning 

in Late Cretaceous time in southern Nicaragua and western Costa 

Rica and· in Eocene time in Panama. Volcanic and pyroclastic rocks 

interfinger with the marine sediments, indicating concurrent volcanic 

activity. 

At the end of early Miocene time strong defor1nation was accompanied by the intrusion of granite and syenite; less intensive deformation continued into late Miocene and Pliocene. 

PRE-TERTIARY ROCKS 

The pre-Tertiary rocks that :form the basement complex in southern 

Central America are quite different :from those o:f northern Central 

America. They consist of a complex o:f igneous and metamorphic 

rocks,. of Cretaceous ( ? ) and pre-Cretaceous age, which is shown on 

plate 1 as a single unit. The basement complex forms tlie principal 

axis o:f · southern Central America, although over wide areas it is 

covered by younger sedimentary and volcanic rocks. The sediments 

that locally overlap the axis range in age from Cret'aceous( ?') to Pliocene; the seaways in which these sediments were deposited were stable 

in some places but highly unstable in others. On the whole, individual 

basins were small, and the sedimentary units deposited in them were 

highly l{mticular. 

In western Costa Rica the basement complex is composed chiefly of 

basaltic volcanic rocks, including flows, pyroclastic rocks, and pillow 

lavas. Diorite and· diabase intrude these roclts in places and' make up 

tlie axis of the Peninsula de Nicoya, wliich trends northwestward 

(Roberts, 1944~ p. 389). On the northeast and: southwest, Late 

Crefaceous, Eocene, and Oligocene sediments overlap the basement 

complex. On the east the marine sediments are covered tiy volcanic 
GEOLOGY 29 

and pyroclastic rocks which were derived from the chain of volcanoes 

of the middle cordillera of Costa Rica. At the Nicaraguan border the 

principal peaks are on the Pacific side of the isthmus, but to the south, 

in central Costa Rica, they are on the Caribbean side. · 

The Cordillera Central is a thick series of interbedded pyroclastic 

rocks and lavas forming a plateau upon which volcanic cones have been 

built. Irazu, the highest of these cones, reaches an altitude of 11,300 

feet. 

In Panama the basement complex is composed of indurated sedimentary rocks, intrusive and extrusive igneous rocks, and metamorphic rocks. Jones ( 1950, p. 899) noted basalt, metabasalt, metatuff, 

hornfels, dacite porphyry, and other rock types near the Canal Zone; 

these rocks have been cmnplexly faulted, closely folded, tilted, and 

highly altered. Olsson (1942, p. 233) 1nentions andesite associated 

with greenstone and sandstone that may be of pre-Tertiary age near 

Punta Cambuyal on the Peninsula de Los Santos. 

ROCKS OF MESOZOIC AGE 

The only rocks of Mesozoic age definitely known in southern Central 

America, in southern Nicaragua, have been described by W egemann 

( Schuchert, 1935, p. 607). They consist of shale and sandstone with 

much volcanic material, are 6,800 feet in aggregate thickness, and contain Late Cretaceous fossils. Cretaceous fossils are also reported in 

northwestern Panama (M. L. Thompson, written communication), 

but thus far the fossils have been found only in boulders, whose source 

is not known. 

TERTIARY SYSTEM 

The Tertiary system of southern Central America includes formations as old as Paleocene, and the succession represents the whole of 

the Tertiary with fair completeness. Woodring and Thompson (1949, 

p. 223-247) have studied the Tertiary formations of the Canal Zone 

and adjoining parts of Panama. They prepared a chart, which is 

reproduced below, showing the correlation of forrn.ations in four areas 

in Panama and the Canal Zone. 

The 3,000-foot thick Gatuncillo formation of middle ( ~) and late 

Eocene age, the oldest known Tertiary formation in Panama, consists 

of mudstone, siltstone, impure bentonite, and limestone lenses. 

The Bas Obispo, Las Cascadas, and Bohio formations, of Oligocene 

age, include much pyroclastic material. The Bas Obispo formation 

is chiefly agglomerate composed of fragments of andesite and basalt 

imbedded in hard tuff; pebbles and cobbles are locally present, and 

in places the unit is rudely bedded. The overlying Las Cascadas 

agglomerate is less indurated and contains more fine-grained material. 

Both formations contain intercalated lavas. The Bohio formation, 
Suggested correlation of Tertiary formations in the Panama Canal Zone and adjoining parts of Panama 1 

A Gaillard Cut and Pacific Ocean Gatun Lake area and Caribbean Madd b . p 

ge side of isthmus, Canal Zone Sea coast, Canal Zone en asm, anama Quebrancha syncline, Panama 

Early Chagres sandstone 

Pliocene Toro limestone member 

. Afi:~:. .11111111111111111111111111111 

c Gatun formation ~ ................................................................ ? 1 .............. ? ....................... ? ........ . 

,s La Boca formation, Pedro Miguel Alhajuela sandstone 

~ agglomerate, Panama tuff member 

Earl Cucaracha formation -~ Calcareous sandstone 

y . ( ) .... member Emperador hmestone member. ? ~ 

----- ' ~'~ Chilibrillo limestone 

Culebra formation -- ~ member l--t------fTTTT'TT11 ' ? .,_. ............................................. .. ...................................................... . 

• • s:: £ Pyroclastic rock and 

Upper member .2 'Cl clay member----- , o § Calcareousbsiltstone .... ~'~ ts(?) 7---.. ....... mem er Late S 'til Limestonelens(?) '§1dl--------------l Q) '"' () ... s ~ Middle member .g Cal~areous sandstone- t3· ~ Quebrancha limestone 

u 0 s11tstone member ""' member 

~ ~ ~ ? 1----~--+--------------~ ~ Las Cascadas :;' Lower .§ c · k 0 Las Cascadas agglomerate ..;;; as 0 .2 Volcamc-roc member . agglomerate .::;: member c; ....... Early -= Bohio formation ~ cU 1---------------------l 

Bas Obispo formation Bas Obispo ~ Boh1o ~ E Gritty sandstone ..................... ........................................... formation ~ formation .2 member )--1------~ .............................................................. 1-------------'l--.l...-----------~ 

Middle(?) 

and Basement complex Gatuncillo formation Gatuncillo formation Gatuncillo formation 

late Eocene 

'--C::_:ta~_:~~(~L_ _ __ __,__ Basement c~Jll~- ~~asement complex Basement complex 

1 Broken horizontal lines indicate that top, or base, of formation in question is not exposed. Vertical ruling indicates hiatus:' omitted between 

Gatuncillo formation and basement complex. Age of Las Cascadas agglomerate is questionable. (Woodring and Thompson, 1949, p·. 223-247.) 

c,.., 

0 

~ ~ t"4 

t:l 

t.:<J 

~ '(TJ 

8 

U2 

0 

~ 

c 

t.:<J 

~ 

~ t"4 

~ t.:<J 

l;:tl 

~ 

~ 
GEOLOGY 31 

estimated to be about 1,000 feet thick, consists of conglomerate, tuffaceous sandstone, and tuffaceous siltstone. It is largely nonmarine 

and is equi'\talent in age either to the Bas Obispo or both the Bas 

Obispo and the Las Cascadas formations, depending on the area, as 

shown in the chart on page 30. 

The Caimito formation, of Oligocene and Miocene age, has been divided into 2 to 5 units. In the Gatun Lake area the lowest member is 

conglomerate and tuffaceous sandstone; the middle member is tuffaceous sandstone, tuff, and thin beds of limestone; and the upper 

member is predominantly tuffaceous sandstone, siltstone, and agglameratic tuff. Elsewhere the formation consists of limestone and tuffaceous sandstone and siltstone. 

In the Gaillard Cut area (the part of the Panama Canal across the 

continental divide), rocks equivalent to the upper part of the Caimito 

formation east of the Canal Zone have been divided into the Culebra, 

Cucaracha, and La Boca formations. The Culebra formation consists 

of carbonaceous shale and mudstone, tuffaceous clastic rocks, and caleareous rocks; a massive lenticular limestone member, the Emperador 

limestone, is present near the top of the unit. The Cucaracha formation is composed chiefly of bentonitic clay; other constituents of 

the formation are shale, siltstone, sandstone, tufl', and conglomerate. 

The La Boca formation consists chiefly of silty or sandy tuffaceous 

mudstone, but in places it contains sandstone, limestone, and conglomerate; members of the formation present locally are the Pedro Miguel 

agglomerate and Panama tuff. 

The Gatlin formation, in the Gatlin Lake area and along the Caribbean coast of the Canal Zone, consists of massive sandstone, siltstone, 

conglomerate, and tuff, and is considered to be of middle Miocene and 

possibly late Miocene age. Its thickness probably exceeds 1,400 feet. 

The Gatlin formation is overlapped by the Chagres sandstone, which 

includes the Toro limestone member, a basal lim,e-cemented coquina. 

Fossils in these units indicate that they are of early Pliocene age. 

Olsson (1942, p. 231-235) has summarized the Tertiary geology of 

the remainder of Panama; he has pointed out that the Tertiary rocks 

occur mainly in elongate marginal belts or embay1nents in the Isthmus 

of Panama. The rocks range in age from Eocene to Pliocene. The 

Eocene rocks in the Tonosi Valley in south-central Panama consist of 

limestone, shale, sandstone, conglomerate, and volcanic material, and 

have an aggregate thickness of about 2,000 feet. Near David, in western Panama, algal and foraminiferal limestones of late Eocene age 

are exposed. Oligocene rocks are widely distributed throughout 

Panama and include coarse clastic rocks as well as limestone and shale. 

The Miocene rocks in Panama consist of shale, sandstone, and limestone; local unconformities within the section show that orogenic 

movements were contemporaneous with marine deposition at many 
32 MINERAL DEPOSITS OF CENTRAL AMERICA 

places. Following the Miocene the seaways in Panama were greatly 

redu-ced in ·extent. Pliocene and Pleistocene formati'6ns are known 

in only ·a few places, principally along the presen:t c·oastlines (see 

Terry, 1956; the geologic maps are much more detailed than pl. 1 of 

this report) . 

The succession of Tertiary rocks in the coastal areas of Costa Rica 

is similar to the succession in Panama. The Atlantic slope of Costa 

Rica, according to Olsson (1922, p. 181-1'83), is underlain by Tertiary 

sedimentary rocks whose main dip is northward. The succession 

includes rocks ranging in age from Oligocene to Pliocene. The 

Oligocene rocks are mainly sandstone, shale, and limestone. The 

Miocene rocks, whose thickness ranges from a few hundred to several 

thousands of feet, include sandstone, dark shale, lignitic shale, conglomerate, and coralline limestone. Olsson ( 1922, p. 205-206; see 

also Woodring, 1928, p. 68, 88) 'pointed out that during the Miocene 

much of Costa Rica was largely submerged; during the early Miocene 

a ·sea ·extended across Costa Rica, connecting the Atlantic and Pacific 

Oceans. Disturbances during the later Miocene resulted in partial 

closing of the seaway, and in the Pliocene the area was elevated. 

Williams ( 1952) has summarized the geology of the central plateau 

of Costa Rica. He pointed out that the plateau consists mainly of 

volcanic and pyroclastic rocks which rest on a ·basement of marine 

sedimentary rocks that range in age from Eocene to Miocene. The 

early volcanic eruptions in the Cordillera ·Central began in the late 

Pliocene or early Pleistocene and filled valleys cut in the pre-Pliocene 

rocks. The flows consist of pyroxene andesites and related lavas and 

pyroclastic rocks. After an interval of erosion and weathering of 

these rocks, part of the Meseta Central was covered by lava that was 

probably derived from two volcanoes, Poas and Barba, probably in 

the Pleistocene. Subsequently, andesitic and basaltic lavas and 

younger mudflows and residual deposits largely covered the older volcanic ·material. 

'QUATERNARY SYSTEM 

In southern Central. America Quaternary ·rocks form a wide coastal 

plain in eastern Nicaragua and part of Costa Rica, and, as in northern 

Central America, there is no coastal plain in much of eastern Panama. 

Major ·volcanism extended froin the Tertiary into the Quaternary, 

but little volcanic activity has continued until Recent time except in 

southern 'Nicaragua and southern and central ·costa Rica. 

IGNEOUS ROCKS 

Igneous rocks form an important part of the Tanges of eastern 

Costa Rica and Panama, where they make up part ·of the basement 

complex. Granite, diorite;and granodiorite are the principal intrusive 

igneous rocks; syenite, monzonite, and other 'Varieties also are reported 
GEOLOGY 33 

(&pper, 1937, p. 120, 134). According to w·oodling (or:;tl ~ommunication), in Panama there were two periods of intr~i<tn; pro~bly 

Late Cretaceo~, and Oligocene an.d early Miocene.. .Jones ( 1:900, p. 

901) has described plugs and dikes of basic r9ek ()f early i\fipcan~ 

age near Colon. Altered lavas and pyrocl~tic rooks, predomin.a~tly 

basaltic and andesitic, also form part of the b.ose1llent complex. 

The volcauoes of southern Central America, like tho.se of northarn 

Central America, are andesitic. Schuchert ( 1935, p. 568) pointed opt 

that volcanoes in Costa Rica and Panama are only mildly active, and 

that they become progressiv~ly mor.e active to the west in ij"icara.gu~, 

El Salvador, and Guatemala. 

GEOLOGIC STRUCTURE 

Central America has been divided into two main goologic aDd 

tectonic regions·: nuclear Central America, which comprises Guatemala, Honduras, El Salvador, and northern Nicaragua; and the 

Isthmian link, which comprises Panama, Costa Rica, -and soathe:m 

Nicaragua (Schnchert, 1935, p. 6; Sapper, 1899, p. ·73-'St>; 1937, p. 

49-65,. 'fhese two regions are sepa-rated by the Nicaraguan lewland. 

Nuclea·r Central America includes the mountain. ranges ef ancient 

folded rocks that extend eastward across Guate.ma1a, Honduras, El 

Salvador, and northern Nicaragua, and form the .structarai frame .. 

work of northern CentTal America. The Isthmian link has .a, ibasemeut 

of igneous rocks with a veneer of Late Cretaceous -and T.erti:a:ry iStrsta 

and forms the young iand ·bridge that -conne~ts Central .f:Mld Soo.th 

America. . 

The ancient anticlinal core of the pre-Permian crystaltline r-ooks is 

exposed in Estado de Chiapas, Mexico, where it is overlapped on ~file 

north by sedimentary rocks of late Paleozoic and. Mesozoic age. 1.'he 

crystalline core extends southeastward, entering Guatem-a4a ·nea:r 

Huehuetenango, where it curves southward in -a 'bJl()ad arc whose oolllte¥ 

is near Rabinal, and continues eastward into '6he coasta"l· :ranges of 

northern ·Honduras and Nicaragua, finally passing out inte the Garibbean Sea. It is inferred from exposures of these rocks on the Isla 

Roatan that the core continues toward Jamaioa, bounding .the 

Cayman ·'Trough on the south. 

Sapper :(1937, p. 41, 42} has emphasized that the major structul'eS 

of Central America were formed 'before Permian ·time and may be itS 

old as pre-Cambrian. The o-ldest trend lines of nuclear <:Jentral America are still evident in the alinement of major ranges and have ·probably to -some extent controlled -the ·more recent orogenic mo-vements. 

The Cockscomb Mountains in 13ritish ·Hoodul'as <fl>re pamllel to :tile 

ranges of Guatemala. Submarine ridges connecting the Mister-iosa 

and Cayman ·Banks may be a submerged eastward continuation of 

the Cockscomb Mountains, bounding the Cayman Trough on the north. 
34 MINERAL DEPOSITS OF , CENTRAL AMERICA 

•. 

The rocks of Paleozoic age that flank the anticlinal core are folded 

in western Gua,temala and seem to be progressively more metamorphosed to the east, so that the shale of the Santa Rosa formation in 

the west becomes phyllite and schist near Puerto Barrios, in eastern 

Guatemala, and in Honduras. 

The rocks of Paleozoic age were folded and eroded in pre-Jurassic 

time, for the Todos Santos formation everywhere rests on folded Permian rocks of the crystalline basement. Intrusions of granite and 

serpentine, probably related to this orogeny, cut the Permian and 

crystalline rocks and may have been emplaced between late· Permian 

and late Triassic time. 

The El Plan formation and possibly the lower part of the Todos 

Santos beds were deposited in terrestrial basins which covered much of 

Central America during the Jurassic, and continental deposition probably prevailed throughout the Jurassic and Early Cretaceous. 

Toward the close of the Early Cretaceous, submergence changed the 

continental basins to marine embayments, and marine limestone and 

dolomite were deposited over an area roughly coextensive with the 

underlying terrestrial beds. Deposition continued in most places into 

the Late Cretaceous. Imlay (1944, p. 1090, 1104) clearly shows the 

probable extent of the Cretaceous seas on his paleogeographic maps 

of Central America. 

The earliest Tertiary beds are coarse clastic rocks of the Sepur 

formation, whose composition shows that they were derived from a 

wide variety of sources including crystalline rocks, Permian limestone 

and quartzite, and limestone and volcanic rocks of Mesozoic age. The 

Sepur strata were probably deposited during orogenic movements in 

Late Cretaceous and Eocene time~ Intrusions of granodiorite and 

diorite that accompanied the orogeny cut the Cretaceous rocks 

throughout eastern Guatemala and Honduras. Folds, largely trending eastward, were developed in the Cretaceous rocks and appear also 

to have involved rocks as young as those of Sepur age. 

The orogenic movements culminated in thrust faulting, first mapped 

in the Departamento de Huehuetenango (pl. 9), which thrust the Permian rocks over the Todos Santos formation and the Cretaceous limestone. The extent of the thrusting is not known, and many such faults 

may be present in central Guatemala. Faulting shown by Sapper 

(1899, table 1) in the northern part of the Sierra de los Cuchumatanes 

may include thrust as well as normal faults. 

The Sepur strata, exposed in Guatemala in the Departamentos de 

Huehuetenango, Alta Verapaz, and Peten, were involved in the folding and the thrusting, and the orogenic movements must therefore 

be as late as Eocene and are possibly in part post-Eocene. However, 

by Miocene time the Peten area had become more stable, for Miocene 
·GEOLOGY 

sedimentary rocks overlapping the earlier Tertiary units are hardly 

deformed. 

Uplift of the ranges in nuclear Central America continued during 

the Tertiary, and the volcanic activity which had begun in Early 

Cretaceous time (Schuchert, 1935, p. 33-36) reached its full force in 

mid-Tertiary time. The distribution of the early volcanoes is not 

well known. Bodies of intrusive rock in the principal mine areas 

may well indicate centers of former volcanic activity. The lava and 

pyroclastic rocks .that accumulated south of the older ranges have an 

aggregate thickness in some places of more than 3,000 feet. 

One of the most striking features of the Caribbean Sea is the Cay-· 

man (Bartlett) Trough (Taber, 1922, p. 91-113; 1934, p. 614-615; 

Woodring, 1928, p. 414-415). It is interesting to note that this trough 

is alined with the southern part of the Peren lowland, which is 

bounded on the south by the complex ranges of central Guatemala. 

The northern borders of these ranges are major faults, possibly of 

both thrust and normal type. Hess ( 1933, p. 34-36; 1938, p. 86-87) 

interpreted the Bartlett Trough as a downfaulted graben block formed 

by shearing in the basement rocks during Miocene time. He postulates that the block south of the fault moved eastward horizontally; 

then, relief of compression permitted complex block faulting south of 

the fault. It seems more likely, however, that the major .tectonic elements of northern Central America were probably formed before 

the Permian. The deformation that caused the present submarine re-. 

lief is, as Hess suggests, probably younger; the deformation may have 

started in the Cretaceous and have culminated late in the Tertiary. 

Bucher (1947, p. 112-113) has also considered the problems of the 

Caribbean Sea basin structure. He pointed out that the region underwent intense compression in Late Cretaceous time; the east side of the 

basin yielded much more than the west side, presumably due to the influence of structures of Paleozoic age on the west in Guatemala and 

Honduras. 

In Honduras, valleys transverse to the eastward-trending ranges 

were formed by block faulting (Redfield, 1923, p. 474-493). Among 

these is the Valle de Comayagua, which is part of a block-faulted area 

extending from the Pacific Ocean northward to the Caribbean Sea. 

Parallel structures along the coast of British Honduras and in northern British Honduras may well be related to these· transverse faults. 

Inasmuch as these faults cut across the trend of the Cayman Trough, 

they are probably of late Tertiary age. 

Meyer-Abich (1952, 1953) ·has described the structural features of 

El Salvador and has discussed the relationship of these features to 

the distribution of volcanoes. He has shown that the principal faults 

trend northwestward, parallel to the major volcanic chain and to the 
36 MINERAL DEPOSITS OF CENTRAL AMERICA 

eoastline of El Sahtador, and that other fault sets strike about N. 30° 

E. and north-northwest. Hot springs and fumaroles in El Salvador 

are thought by Meyer-Abich ( 1953) to be related to stru~tural ft3a-

:tures that trend northwestward, parallel to the zones of ma~or 

::faulting. 

Williams and Meyer-Abich (1953) have shown that Lago de Ilopango in El Salvador occupies a graben that developed over a long 

period of time and was partly filled by a succession of lavas and pyroclastic rocks during the stages of its formation. Other lake basins 

in Central America are also believed by the present writers to have 

been formed, in part at least, by collapse. Among the most notable 

of these are Lago de Atithin and Lago de Amatitlan in Guatemala. 

ORE DEPOSITS 

The p,rincipal objective of the Central American Minerals Mission 

was to evaluate the deposits of strategic minerals in Central America. 

Deposits of antimony, chrom.ite, 1nanganese, 1nercury, mica, and quartz 

were examined, and some of them were mapped in detail. Studies of 

deposits of other 1ninerals, especially of iron and base metals, which 

offered hope of postwar production were also undertaken. In addition, a short account of the gold and silver deposits of Central America is included. 

The purpose of this report is to give a general picture of the mineral resources of Central America. Because of time limitations, no 

exhaustive regional studies were attempted. In some areas only a few 

typical deposits were examined in order to gain an idea of the potentialities of the areas. Actual mapping was ca~ried on chiefly in 

districts o£ known reserves or in producing areas reasonably close to 

routes of transportation. 

In this part of the report, following the history of mining, the deposits are arranged alphabetically according to commodities. The 

commodities are in turn subdivided geographically from northwest to 

southeast, and are further subdivided into areas or districts and individual deposits. 

HISTORY OF MINING 

Long before the discovery of America by Columbus, gold was prized 

by the Mayans and other Indian .races that inhabited Central America. In Costa Rica, Panama, and Honduras, gold ornaments fashioned in various forms have been discovered in tombs and at sites of 

worship. When Columbus came to Honduras on his fourth· voyage, 

in 1502, he was greatly interested in the gold orna1nents worn by the 

natives (Wells, 1857). The first settlers in northern Honduras, in 

1509, must have had as one of their objectives the search for the source 

of the gold. Exploring parties penetrated far inland, but it was not 
EITSTORY OF MINING 37 

until about 1524; that Olu.ncho., the principa~ so~rce 9~ th~ pl~c~r gold, 

was visited ; the Spaniards began placer op.e1:atio;ns 5,09¥ :;tft~rward. 

Presumably the Spaniards attempt~d t~ enlist the. yolunt~ry aid of 

the Indians jn increasing the production of go~d, ~nd when that 

.attempt failed they enslaved them ~:ud forced t~em tp 'Y9rk i:r;I. t~e 

mines. As the Indians were given little except thei~ fOPd, which was 

largely available ne~~by, mining costs were low. Low-gr~d~ depos~ts, 

containing only small pay streaks not now profitable to wine, W.ere 

worked down to the water table and, in pla~s, below it. 

The Spaniards were trained in lode as well ~s placer mining q.nd 

during the few decades after 1524 must have discover~~ most of the 

known gold-bearing lodes in Honduras while searc!ling fo:r additional 

placer fields. Only a few of the miner~l deposits ~x~mined during the 

past 50 years do not show signs that they were ¥:nown to the Spaniards. In some places the principal ore shoots o.f large ore dep~sits 

were not found because of the lack of facilities for deep mining, but 

since the slave labor supply was nearly inexhaustible, great effort was 

expended on veins too low grade or too narrow to be e*ploited by 

present 1nethods. The Spaniards were not bound by present considerations of the cost of operations, for any production al:>Ove administrative costs, however small, was profit. To say, therefore, that a 

property has merit simply because it was worked by the Spaniards 

may be misleading. 

The Spanish domination continued for nearly 3 centuries, but although church chronicles and political archives contain numerous references to mining, few data are available on actual production. However, judging from the extent of the workings left by th~ Spani~rds, 

it seen1s that the production must have been substantial. 

As time went on, the bonds between Spain and Central Ameri~~ 

became weaker, and insurrections that began early in the 18th century 

finally culminated in the renouncing of Spanish authority in 1821. 

From 1821 to 1839 the Central American countries were united in a 

loose confederation; this period was characterized by a succession of 

local uprisings fomented by different groups attempting to gain power. 

These uprisings were interspersed with quiet periods, but little organized mining was carried on because of the instability of the local 

governments. In 1839 the confederation was dissolved and the Central American countries were outlined in approximately their present 

form. During the 1840's and 1850's local strife prevailed everywhere 

and mining virtually stopped. After the early 1850's, when the 

Central American governments became stabilized, the political climate 

again favored foreign investments. 

The discovery of gold in California must have renewed interest in 

the gold deposits of Central America, for many of the miners bound 

for California passed through Central America on their way north. 
38 MINERAL DEPOSITS OF CENTRAL AMERICA 

In 1856 an English and French company began to mine the rich silver 

veins of the Concepcion district in eastern Guatemala. Shortly afterward, foreign investors, spurred by the writings of Wells (1857), 

Dollfus and Montserrat (1868), and Belt (1888), becan1e interested in 

Central American mining, and operations were begun in the J abali and 

Chontales districts of Nicaragua and the Aguacate district of Costa 

Rica. Later, the Rosario and Y:uscaran mines of Honduras came into 

production. 

The construction of railroads, which began in the 1870's in several 

Central American countries, also aided mining activities. The peak 

of mining was reached between 1880 and 1910 when other properties 

in Costa Rica and El Salvador began production. Many of the 

bonanza shoots were mined by 1910, and, although the introduction 

of the cyanide process prolonged the operation of many of the mines, 

production dwindled and reached a low point betwee.n 1920 and 1932. 

In 1932, when the price of gold was increased to $35 an ounce in 

the United States, many mines were reopened and some new properties 

were put into operation. By 1938 the Neptune, La Luz, La India, 

and other d~posits in Nicaragua; the .Monte Cristo, Potosi, and San 

Sebastian mines in El Salvador; and the Abangares, La Union and 

others in Costa Rica were in operation. 

World War II caused some properties to close down and others to 

decrease production, but on the whole production was fairly well 

maintained. Increased activity in mining in Central America has 

been shown in the postwar years, and it is probable that any property 

with merit will be thoroughly tested. It is especially noteworthy that 

base-metal deposits are receiving more attention, and three lead-zinc 

operations-in Guatemala, in El Salvador, and in Honduras-were 

producing concentrates in 1951. Tests were being made in 1952 preparatory to installation of copper concentrating and smelting equipment in Nicaragua. 

ANTIMONY DEPOSITS 

Antimony deposits are known in Guatemala, Honduras, and Nicaragua. All the deposits are associated with Tertiary rocks exposed 

in regions of mid-Tertiary volcanic activity. For the most part they 

form pods or narrow veins, and individual ore bodies are small. The 

antimony deposits do not occur in well-defined districts, but appear 

to be widely scattered throughout the dissected volcanic plateau. 

Although attempts have been made to produce antimony in the three 

countries mentioned, ore has been shipped only from Honduras. Total 

production amounts to about 700 short tons, of which the major part 

has come from the El Quetzal mine in the Departamento de Copan. 

Because of the remoteness of the deposits and the consequent high 

shipping costs, attempts at exploitation of the deposits have not been 
ANTIMONY DEPOSITS-HONDURAS 39 

encouraging. Some of the mines can be profitably operated on a 

small scale in times of high prices, but no large production can be 

expected from deposits thus far discovered. 

The information from which the following section on antimony deposits was compiled was furnished by several geologists. Roberts 

mapped the El Quetzal, Las Flores, San Fernandez, and La Union 

deposits in Honduras and the La Cadena deposit in Nicaragua. Fred 

H. Dakin ( 1939, unpublished report) kindly furnished the data for 

descriptions of other deposits in Honduras. Irving and P. W. Guild 

( 1942, unpublished report) described the deposits in Guatemala. 

HONDURAS 

EL QUETZAL MINE 

TheEl Quetzal mine (lat 14°47' N., long 88°58' W.), in the Departamento de Copan, Honduras, is 3 miles south of San Agustin near 

the summit of the Sierra del Gallinero, at an altitude of 5,500 feet 

(fig. 1). Trails extend from the mine to Copan, the nearest shipping 

point, and also to Santa Rosa. 

INDEX MAP Of' fiONilURAS 

f:::·~.:\OJ Slope wast! and talus 

D;onteandrhyolite 

~-::I 

~ 

Micaandgraphiteschist 

~ 

~ 

Inferred contact 

~ 

Strikeanddipoffoliation 

+ Strikeofverticalfoliation 

ADIT JO 

~1767 

Adit,wittlaltitude inmete4's 

~ 

Opencut 

11/IIIIAIIIIII 

Dump 

2f>LL~---'---..L..-_!?feet 

5l....-JO---l.----l.--'---'-!fl"elero 

Contoor interval 5 metefs Datut~~iaualeuel 

Geologyandtopo~raphybyRalphJ.P~l944 

FIGURE 1.-Geologic map of the El Quetzal antimony mine, Departamento de Coptn, 

Honduras. 

388364-5.7-4 
40 MINERAL DEPOSITS OF CENTRAL AMERICA 

The mine began production in December 1941 and up to October 

1944 had yielaed 575 short tons of chemical-grade antimony or~, averaging about 62 percent antimony (see table below). The bulk of this 

ore was shipped to the Wah Chang Trading Corp. in New York, but 

the last 100 tons produced in 1944 was shipped to the Harshaw 

Chemical Co. in California. 

Antimony ore produ,ceq .from the El Quetzal mine, Honduras, 194-2-4-4 1 

Year Weight (short Antimony (per- Remarks 

tons) cent) 

1942 ____ 201. 6 6L 32 Includes 2.13 tons of ore from the Las 

Flores mine. 1943 ____ 200. 31 62. 20 1944 ____ 175.0 62. 0 Estimated. 

I Data published with permission of mine owners. 

The owners report that exploratory work was carried on during 

1947, 1950, and 1951, but no shipments were made. The workings 

consist of 11 adits and several opencuts which follow the ore zone for 

a total length of 420 feet and a depth of 151 feet (pl. 3). 

Geology 

Graphite and mica schists of unknown age which strike westward 

and dip steeply (pl. 4; fig. 1) have been cut by dikes and sills of diorite 

and felsite. In the mine area the rocks have been highly sheared and 

fractured along faults that trend north to N. 10° E. and dip steeply 

westward; the shearing extends over a width of 50 feet or more. The 

shear zone contains the ore bodies, which are commonly in fault slivers 

and in fragments of intrusive rock. 

Description of the ore bodies 

The ore bodies are lenticular pods and veins. Stibnite is the most 

abundant antimony mineral except near the surface, where it has been 

partly altered to antimony oxides; it is locally accompanied by small 

quantities of pyrite, arsenopyrite, and sphalerite. Generally the ore 

consists of almost solid stibnite with little gangue, but in some places 

quartz and a carbonate-probably dolomite-are found in cavities and 

also crystallized with the stibnite. The ore minerals in part fill cavities in the fractured schist and igneous rocks, and in part replace the 

rocks. Euhedral stibnite needles partly fill cavities in many places in 

the shear zone, indicating that cavity filling was the principal veinforming mechanism. 

The ore zone extends along the strike for 420 feet and in 1944 had 

been mined more or less continuously for 300 feet of this distance. 

Stopes extended up to the surface from a depth of 151 feet in the northcentral part of the workings. The ore was 1nined by overhand stoping 
ANTIMONY DEPOSITs-HONDURAS 41 

followed by filling. Because of the friable nature of the ore, the loss 

in the fine fractions was as much as 40 percent. Moreover, owing to 

irregularities in the veins and lenses, pillars of ore have had to be left 

in some places, and local caving of stopes has caused further losses. 

Two principal ore zones, 1 north and 1 south of the winze in adit 6, 

have been mined (pl. 4; fig. 2) . The north zone comprises a series 

of lenses, some of them overlapping, that range in thickness from 3 to 

18 inches. The ore has been mined almost continuously along the 

strike for 200 feet and downdip from the surface nearly to level11, a 

vertical distance of 151 feet. The zone. was in the sheared schist of 

the footwall of the principal dike; in some places it was in contact with 

this dike, but in most places a foot or more of sheared schist separated 

them. The ore shoot narrowed downward, and above level11 the stope 

length was only 50 feet. Here the ore body consisted of 2 veins, each 

2 inches wide, separated by a dike 3 feet wide. One vein widened upward and was a foot wide at level 5. Between winzes 3 and 6 ore was 

first mined in an opencut, but in 1942 the cut was abandoned because of 

slides, and underground mining began on levels 3, 6, and 7. The ore 

was stoped upward to the cut and was then followed northward and 

downward. Later, levels 4, 5, 10, and 11 were driven to explore the 

ore shoots at depth. 

The major part of the ore mined came from the stopes south of 

winze 6. The ore was stoped discontinuously along the strike for 

200 feet and from the surface downdip to level 10, a vertical distance 

of 100 feet. The ore pods were 20-40 feet long, were as much as 

30 inches thick, and were composed of solid stibnite. The principal 

stopes were mined from lower level 4 to the open-pit level south of 

shaft 3. As shown in plate 4, some of the ore pods overlapped, and 

locally 2 or 3 parallel pods were mined together. 

The stibnite ore bodies occur in crushed schist and also in dike 

rock. The major part of the faulting probably preceded the deposition 

of stibnite, furnishing channelways for introduction of the ore-forming solutions; however, shearing continued after deposition of stibnite, 

for in many places the stibnite has been fractured and crushed. 

The dike rocks played an important. role in the localization of the 

ore bodies. Shearing stresses caused minute fracturing of the dikes 

and adjacent schist, providing open spaces through which solutions 

were able to move freely. The open spaces were filled with stibnite, 

and continued fracturing reopened the fissures and again permitted 

the entranee of antimony-bearing solutions. 

No ore was found in adit 9, which is east of the principal ore zone. 

A small pocket was found at shallow depth beneath the stream channel 

in front of the adit portal. Adit 4 was originally driven to intersect 

ore bodies exposed in the bottom of the pit, but it led to the discovery 
Jol:;l. 

1':.,:) 

SOUTH 

Meters 

1805 

1800-j . ////\. ~ ~ \~ / t"-1800 

~ 1-4 

1795-l \///////\ /7//// /l:!ii/ / /45-sli//""7\/ /// /;N,.._ L:Y.L /.!./ /// J\.,' /./ .".// / ""-- 1-1795 2: 

t;l 

P:1 

> 1790-l V////A'/A //////// /Y /i/ ///////A" A"////////// /YV // Y /////////1/////// /"A l-!790 t"4 

t;; 

1785-l r////YY/A v //////////1 ';i.;_<v;>u/./ // //;;vv ////////// /!~/ /////// //>-...._ ---:y-rr.r7~rr.r77~J785 t;f 

'"d 

0 

w. 

1-4 

1780-l '</////I I V//////////Y~/////////VV/~;//////////////VV/YY/// 1-1780 1-3 

732 

0 1775-l V //////// /!/i/ /////////////// /I.L./_L.L'../.././../_LL.L.././~ ~~ .. ~~ -·~~ ~ J 1.-1775 "-':1 

c 1770-l '</ / ,;::../ /// )""'/ ///////A' I ~ I -rJ....J.....L... 1.-1770 

1:-tj C:.ft"'-rC:.,.,.r.<> 

~ P:1 

1765-l L.'(-'/ y //// 7'./i:,~ ... ~;-;-;;::;-~; :\ 

f'~" > EXPLANATION t"l 

1760-/ 1·\V /// //:/i/ /////A ~ Stoped area 

1760 

1:-tj 

~ 20 30 P:1 Figures denote width of 1-4 

1755-l ~~/~~~/~~..//~~~ ore in centimeters 1755 

~ 20 Meters 

1750. Datum is ap roxlmate sea level 1750 

FIGURE 2.-Projected longitudinal profile of the El Quetzal antimony mine, Departamento de Copan, Honduras. 
ANTIMONY DEPOSIT8-HONDURAS .43 

of several new ore bodies which account for a considerable part of the 

ore mined. Eighty feet from the portal a lens as much as 24 inches 

thick was mined; this lens was followed northward and 2 ore bodies 

were stoped from the level upward to the pit. These stopes were 

on ore bodies that dipped steeply east, presumably along minor shear 

zones in the main zone, which dips steeply west. Winze 4 was sunk 

on o:re in a parallel lens west of stope 2 and was used to remove ore 

from the Miguel and Lino stopes. ·The Miguel stope contained a 

body of ore as much as 30 inches wide that was composed of solid 

stibnite in schist between parallel segments of a dike. This ore was 

mined downward to the Lino level, where it narrowed to about 12 

inches. In the Lino stope, an ore body averaging 6 inches in thickness 

was mined down to lower level4. Adit 7 was driven below the surface 

pit to mine ore from a lens that was 24 inches wide in some places. 

The ore lay between dike rock and sheared schist that contained much 

pyrite. Exploration south of the crosscut and to the west was not 

encouraging. In September 1944 the stope from level 10 had been 

extended to about 15 feet above level 10, but only small pockets of 

stibnite had been found. 

In the stope between winzes 3 and 6 the ore lens at level 5 was 

2-3 inches thick. Upward it thickened, becoming 12 inches thick 

near level 3 and 18-20 inches thick from there to the surface. Near 

winze 3 there were two parallel lenses of ore. With the exception of 

the block below level 10 and west of winze 3, the ore has been stoped 

to the surface. None of these workings were accessible at the time of 

the authors' visit. 

In the stope between adit 5 and winze 3 the ore occurred in lenses 

ranging from 3 to 12 inches in thickness ; in several places the lenses 

overlapped. Some of the ore lay between the dike and sheared schist, 

and some was in the shear zone near the dike. The ore shoot pinched 

to a few inches in thickness at shaft 5 but became thicker at raises 

5 and 3 and was as much as 12 inches thick above level 5. Ore at 

depth and north along the drift is not promising. 

Below level 5 the ore shoot was explored by means of winze 5; 

stibnite needles and occasional small pockets of stibnite were found 

along the dike contact, but none were large enough to be stoped. Raise 

11/5 was run from level11 to stope an ore shoot that extended upward 

from the level. Although the ore shoot rarely exceeded 6 inches in 

thickness, it was continuous and of uniformly high grade. 

Suggestions :for further prospecting 

All the easily available ore at the El Quetzal mine above level 11 

( 5,754.5 feet elevation) has been stoped. Exploration along the 

strike south and north of the principal ore bodies has not been promising, but, as it has not been thorough, further work may be warranted. 
44 MINERAL DEPOSITS OF CENTRAL AMERICA 

Exploration should also be extended west of the present workings to 

see whether other parallel mineralized shear zones are present. Up 

to 1951, new ore discoveries on the lowest levels were reported to be 

small, but other ore bodies may exist at depth. 

Promising discoveries were made in 1948 west of the present wa.rkings described, and other antimony deposits are known in the vicinity 

of El Qm~tzal, but none of them have been explored. The following 

occurrences were reported by Mr. Nater: Rafael Cuesta, who lives in 

the village of Santa Cruz, reports stibnite on his property ; antimony 

ore is reported near La Encarnacion; and stibnite veins as much as 

an inch in width were discovered in dike rock at the water intake for 

the San Andres power plant. Antimony ore is reported also in the 

mountain range west of El Quetzal and in adjacent parts of Guatemala. 

BENJAMIN MINE 

The Benjamin mine is about one-half mile from a boat landing at 

Pedernales, near the southwest corner of Lago de Yojoa, at an altitude 

of 2,800 feet, about 300 feet above the lake. The property is owned 

by Eduardo da Costa Gomez, Andres Leiva, and Dr. S.M. Waller of 

San Pedro Sula. 

The ore is composed of mixed antimony sulfide and oxides accompanied by witherite and quartz; it forms pockets in shear zones that 

trend N. 20°-70° E. and cut limestone. The pockets are small, widely 

separated, and do not appear promising. Antimony is also reported 

nearby, at Santa Lucia. 

SIRIA MINE 

The Siria mine is at SuyataJ, Departamento d.e Tegucigalpa, about 

50 miles north of the town of Tegucigalpa. It can be reached by automobile during the dry season. The property is owned :by Gen. Pedro 

Triminio and Marco Carla. Raudales of Tegucigalpa. The workings 

are shall-ow cuts and a short adit. 

The ore, stibnite in black sl.ate, is associated with intrusive basalt 

which also contains a little stibnite. The pockets of ore .are small and 

widely 'SCattered. Two shipments w-ere made in 1935 : 21.65 tons containi:ng ,52.49 peillcent antimony was sent to London, .and 11.3 tons 

containing 47.18 percent antimony was .sent to New York. In 1941 

a shipment of .5 tons was .sent to El Segundo, Calif.; this ore contained 56.15 percent-antimony and 0.025 percent arsenic. 

Other antimony deposits are reported near Cedr.os, Departamento 

de Tegucigalpa, but these were not visited by Mr. Dakin. 

LOS 'HORNITOS MINE 

The Los Hornitos mine is :9 miles ·east of Y oro, Departamento de 

Y oro, ·at an altitude of .3;400 feet. ·Olanchito, the nearest ·shipping 

point, is about 45 miles to the northeast. The ·mine is owned by Miguel 
ANTIMONY DEPOSITS-HONDURAS 45 

Cubero, Andres Leiva, and Dr. 8. M. Waller of San Pedro Sula, but 

in 1944 it was leased to Dr. P. Jerda Kahle of New Orleans. 

The ore forms stringers and pockets in a shear zone 10 feet wide 

which strikes N. 81° W. and dips 40° NE. It is mainly stibnite, with 

some antimony oxide and barite. Shallow cu.ts extend for about 400 

feet aloug the shear zone. Twenty-seven tons of ore was shipped by 

Sr. Cubero in 1938, 25 tons of it to Germany and 2 tons to Italy. The 

German shipment contained 48.8 percent antimony. The ore was 

shipped by airplane from Y oro to Olanchito, and thence over the 

Standard Fruit Co. railroad to the port of La Ceiba. 

Stringers of stibnite in granodiorite and diorite are reported in 

prospects at Sierra Prieta and Puertecito, about 3 miles from the Los 

Hornitos mine. I:AS 'F'LORES DEPOSITS 

The Las Flores denounceme:nt,1 4 miles west of Copan, Departamento de Coprail, is near the Guatemalan border. The property is 

owned by Manuel Bueso of Santa Rosa de Copan and Rafael Villanel, 

Enrique Segura, and Armando J. Castaj·ones of Copan. So far as is 

known only 5 tons of ore had been shipped from these deposits up to 

1943. It was sent to the Harshaw Chemical Co., Los Angeles, Calif., 

and contained 37 percent antimony. 

The country rock is rhyolite, which may be intrusive or extrusive~ 

Tuffs and clastic sedimentary rocks crop out near Las Flores. 

Antimony deposits have been explored at three places in the arear 

One, at an altitude of 4,950 feet, consists of smaU pookets of stibnite 

in rhy~lite along a -fracture zone trending N. 45° W. Twenty or thirty 

tons of ore estimated to contain 20-30 percent antimony was mined in 

the course of exploration. The .fracture zone has been explored to a 

depth of 24 feet and for :SO feet along the strike, but no material of 

shipping .grade has been found. Other workings are at altitudes of 

4,690 feet and 4;300 feet. The highest opening is a shallow cut in 

rhydlite; although some float of good grade was.:f.ound near this opening, the ore has not been found in place. The other workings explore 

a stibnite vei'n in rhyolite. The vein strikes north and dips 35° E., 

nearly parallel to the slope; it was as much as 8 inches thick and was 

1nined for 50 feet along the strike and as much as 30 :feet downdip~ 

The 5-ton shipment of ore, containing 37 _percent antimony, came from 

this vein. 

Although no promising ore bodies have been found in the 'Las Flores 

area, further prospecting may be warranted because o'f the widespread 

shows. 

1 A rnining~Iaw term that refers both to a claim made on land to which the government 

holds mtning'tiglits and· the a~t of making (denouneh:fg) 'the eltihn. 
46 MINERAL DEPOSITS OF CENTRAL AMERICA 

SAN FERNANDEZ MINE 

The San Fernandez property, owned by Arturo Lainez and others 

of Talanga, Departamento de Tegucigalpa, is about 2 miles north of 

the village of Jalaca. About 5 tons of float ore was shipped from the 

property by the Casa Uhler (a business house) in 1941. The workings 

consist of 2 shafts, 15 and 20 feet deep, and shallow opencuts. The 

ore occurs in and adjacent to fractures trending N. 10°-30° W. in 

limestone. Up to 1945 only small pockets had been found, and the 

outlook for future development is not promising. 

SAN FRANCISCO MINE 

The San Francisco mine is near the head of the Rio Guaymas, at an 

altitude of about 2,600 feet, 50 miles by trail from El Progreso. From 

El Progreso, the nearest rail shipping point, ore goes to Puerto Cortes 

for shipment by steamer. Miguel Cubero of San Pedro Sula owns the 

mine. In 1941 he shipped to France 5 tons of ore, which assayed 51 

percent antimony. In 1944 he is reported to have shipped 40 tons to 

the United States, but its tenor is not known. 

The ore is in pods associated with quartz that cuts schist in a shear 

zone striking N. 47° W. and dipping 72° SW. The pods are as much 

as 18 inches wide but are generally no more than 3 or 4 feet in length. 

The ore zone crops out on both sides of the Rio Guaymas. 

LA UNION MINE 

The La Union mine, 3 miles northwest of the town of La Union, 

Departamento de Olancho, is near the headwaters of the Rio Mangulile 

at an altitude of 3,800 feet. The area is accessible by plane or by trail 

from Coyoles, a shipping point on the Standard Fruit Co. railroad. 

The property, originally denounced by Francisco H. AntU.nez and 

Francisco Garcia, was owned in 1944 by Eleazar F. Vargas of Tegucigalpa. In 1941 27 tons of ore containing about 40 percent antimony was produced and shipped to New York. Sr. Vargas leased 

the property in 1943 to Manuel Bueso and Rudolf N ater of Santa 

Rosa de Copan. During late 1943 and early 1944, 30 tons was mined 

and sent on mlileback by way of Coyoles to La Ceiba for shipment 

to the United States. 

The rocks in the area are interbedded red sandstone, conglomerate, 

and shale of the Metapan formation. In the vicinity of the antimony 

deposits these rocks lie nearly flat, but elsewhere they are gently folded. 

The deposits occur in a fault zone, trending N. 30° E., that cuts 

these rocks. 

The workings consist of several shallow trenches and opencuts and 

three short adits. An adit at the south end shows a few small veinlets 

and pockets of stibnite in fractures that strike N. 30° E. and dip 

55°-70° SE. The trenches above and below the adit are in silicified 

rock, but they show no stibnite. The central workings are in barren 
ANTIMONY DEPOSITs-GUATEMALA AND NICARAGUA 47 

red pebbly sandstone. The north workings show stibnite on fractures 

trending northward and eastward; the veins are as much as 6 inches 

wide but are discontinuous. The open pit that yielded the 27 tons of 

ore mined in 1941 was caved at the time of Roberts' visit in 1943, and 

no ore could be seen. Subsequently an ore body was discovered that 

yielded 30 tons of ore, which was sorted to a grade of 62 percent 

antimony. 

With further exploration, other ore bodies may be found, but it appears that this mine will be productive only during times of high 

prices. 

GUATEMALA 

LAS TABLAS DEPOSIT 

The Las Tablas antimony deposit is about 6 miles east of Palencia, 

Departamento de Guatemala. Palencia can be reached by car from 

Guatemala City, a distance of 22 miles. The property, owned by Manuel Franco, is at an altitude of about 5,400 feet. The workings consist of a caved adit, said to be 7 feet long, in volcanic rock and clay. 

The material on the dump and on a nearby bank shows disseminated 

stibnite needles. It is reported that a pocket of ore was mined and 

shipped, but the amount is unknown. .A bin nearby contained 5 tons 

of ore, largely fine material, when visited by Guild. Other antimony 

prospects are reported nearby, but none of them have been explored. 

EL CARRIZAL PROSPECT 

The El Carrizal antimony prospect is about .10 miles by trail northeast of Olapa, Departamento de Chiquimula. The deposit was explored in 1936 by an English company, but no shipments have been 

reported. The antimony ore is in volcanic rocks; only a small pocket 

was found. .All the ore has been mined out except for a few remnants 

in the workings. The outlook for further production is not promising. 

EL HORNO PROSPECT 

TheEl Horno prospect is 18 miles east-northeast of Olapa and about 

5 miles northeast of Carbon eras, near the Guatemala-Honduras border. No production is reported. 

The antimony ore is in veins in granodiorite, which in this area intrudes phyllite. The veins are narrow, commonly lh-6 inches wide . 

.A vein 2 feet in maximum width is said to have been found in the 

area. Such a vein might be profitably mined during times of high 

prices for antimony ore. 

NICARAGUA 

LA CADENA PROSPECT 

The La Cadena antimony prospect is 90 miles north of Managua in 

the Departamento de Nueva Segovia, near the Honduras border. To 

reach the property, one must go west 2 miles by road from the village 
48 MINERAL DEPOSITS OF CENTRAL AMERICA 

of Palacaguina, then 1 mile northwest by trail. The Inter-American 

highway passes about 1 mile south of the. property. The owners are 

Pio Castellon and others of Managua. No ore has been shjpped. 

Palacaguina. is surrounded by. rolling hills .that rise about. 2.,500 

feet above sea level; some p,ea~ to the, east, north, and west rise to 

4,000 feet. The hills are for. the. most part volcanic flows a11d pyroclastic rocks, but in the more deeply incised valleys the underlying 

schist is exposed. 

The mine workings, which consist of 2 pits-25 feet deep and 15 

feet deep-and 3 short adits, are in mica schist that has been cut by 

quartz veins and is complexly sheared. Dikes of altered igneous rock, 

probably andesite, intrude the schist and were probably channels for 

the volcanic flows exposed in the hills nearby. 

The ore bodies consist of stibnite with a little antimony oxide, pyrite, and quartz. Although the st.ibnite is in some places nearly pure, 

it is generally intergrown with the quartz and contains pods and fragments of the enclosing rock. The ore bodies are lenticular or irregular in shape and occur in the dikes and in the adjacent schist. The 

largest body mined was about 10 feet long, 5 feet deep, and as much 

as 3 feet thick. 

At the time of-visit in 1942, only a little ore showed in the workings. 

A few tons of siliceous ore was piled near the workings. Careful sorting would be required to obtain a product of shipping grade. 

CHROMITE DEPOSITS 

Chromite deposits.in Central .America have been exploited only in 

Guatemala. Here the deposits are associated with intrusive serpentine and peridotite, which form two discontinuous belts extending 

from the.Mexico-:Guatemala border eastward to Puerto Barrios (pl.1). 

GUATEMALA 

Chromite deposits have been found· in three areas in Guatemala : in 

the .Jalapa district, in the Cabanas district, and near Morazan. Of 

the three, the Jalapa district has been the most productive. 

PRODUCTION 

Chromite was first discovered in Guatemala by Fred Cutforth in 

1917 at the Gorona deposit near Jalapa. Later this deposit was purchased by the International Railways of Central America and its development was begun. Other deposits were found nearby, and between 1918 and 1920 about 2,700 long tons of high-grade metallurgical 

chromite was produced. In 1930 the Jalapa deposits were leased to 

the Vanadium Corporation of America, which since then has operated 

the mines on a small seale. Between 1930 and 1943 about 6,300 long 

tons of·chromite was· shipped~ from the deposits. (See table below.) 
CHROMITE DEPOSITS-GUATEMALA 49 

The ore in the Cabanas district·was discovered by Mariano Eskanasy in 1918~ .As the depos.its· were· small they.·wer& not immediately 

developed, but ·when prices of chromite ore increased ;in :1943 'too properties were brought into production, and 850 long tons of metallurgieal chromite was shipped in 1943 and 1944; 

Prod11,ction and partial analyses of.chromite ore from Guatemala1 1918-4-5 

[Data.fur.nishecl.by Vanadium Corporaliion of.Amedc::a] 

Mine Tons Cr20s FeO C:r:Fa 

(long} (pe11cent). (peroont) 

Corona _______________________ 1 3,465 52.56 14. 01 3.50 La Gringa ____________________ 1 5,357 55. 30 14. 14 3: 00 

La Paz no. 1 __________________ 491 58.00 13. 12 3 .. 35 

La Independencia ______________ 272 55. 70 13. 16 3. 16 

La Esperanza _________________ 268· 56.02 12.50 3. 17 La Joya ______________________ 2 500 51. 00 ---------- 2. 7 La Corona ____________________ 2 100 ---------- ---------- ---------- Buenos Aires __________________ 2 75 53.00 ---------- 2. 8 

J Some ofthe tonnageincluded was produced between 1918and 192d~ but the assays ar~ ofmaterJaLsllip~d · only after the property was acquired by the Vanadium Corporation of America in 1930. • 2 Estimated. . 

Sr. Eskanasy shipped two lots of ore from the deposits of the Cabanas area in 1945 ; the analyses in percentages are as follows: 

Production and part·ial analyses of chromite ore, Cabanas area, Guatemala, 191,.5 1 

i Tons (long) I CnOs FeO Si02 A bOa MgO' s p Cr:Fe ' i 

I 

i 634. 34 50. 41 12.74 4. 80 9 .. 60 15.65 0. 1 Tr. 2. 70 

: 160. 63 48.31 11. 97 6. 71 9. 52 15.94 . 014 Tr. 2. 76 

1 Names of mines not known. 

GEOLOGY: 

The chromite deposits are in serpentine· and· peridotite· that crop 

out in two roughly. parallel bands extending. eastward across Guatemala. The peridotite and serpentine cut sedimentary and metamorphic rocks of Paleozoic and pre-Paleozoic age and were probably intruded at the close of the Permian period. 

The peridotite, where fresh, is generally dark green or black. When 

altered to serpentine it is commonly greenish, in places a light yellowish· green, but for the most part medium to dark green. Slopes de~ 

vel oped on the serpentine in low dry areas are generally, smooth, with 

a. thin soil that supports only grasses. and shrubs; in high moist areas 

conifers generally predominate. 

Because of shearing, most of the. serpentine is highly slickensided 

and minutely fractured; locally a schistosity trends eastward~ Dikes 

of basalt, andesite, and diorite associated with later volcanismjnk,ude 

the serpentine. 
50 MINERAL DEPOSITS OF CENTRAL AMERICA 

DESCRIPTION OF THE ORE DEPOSITS 

The chromite deposits occur in serpentine as irregular masses, lenticular bodies, and disseminated nodules. The ore bodies are generally 

small, containing from a few pounds to several hundred tons. At the 

La. Gringa. mine several adjoining ore bodies which were mined 

together yielded 5,357 long tons of ore (pl. 5). The ore is generally 

massive black chromite whose texture ranges from fine to coarse. In 

places serpentine and grains of other silicates are sparsely disseminated in the massive ore. Some ore bodies are bounded by shear zones, 

but others show a gradation from nearly pure chromite through a. 

transitional zone, a few inches to several feet wide, that consists of 

a mixture of silicates and chromite grains and nodules, to wallrock 

containing only sparse chromite. In addition to chromite, the deposits 

contain the chromium-bearing garnet uvarovite and the chromiumbearing chlorite kammererite. 

The chromite, relatively high in Cr20 3 and low in Fe, meets the 

requirements for metallurgical use. A series of partial analyses made 

by Stevens {1944, p. 14-15) on ores collected from the Jalapa district in Guatemala. by W. D. Johnston, Jr., in 1941, is shown below. 

Partial analyses of chromite ore from the Jalapa district, Guatemala 

[R. E. Stevens, analyst] 

Mine CnOs Cr Fe Cr:Fe 

LaPaz _______________________ 60.26 41.24 12. 12 3.40 

LaEsperanza------------~---- 61. 10 41. 81 11.20 3. 73 I>o _______________________ 60.82 41. 63 10.51 3.96 Salvador ______________________ 59.39 40.63 11.91 3.41 Corona _______________________ 56. 15 38.41 11. 13 3.45 

Samples of chromite ore from some of the deposits of the Cabanas 

district were collected by Irving in 1943 and 1944 for comparison with 

the Jalapa ores. They were analyzed with the results shown below. 

Partial analyses of chromite ore from the Cabanas district, Guatemala 

Mine or prospect CrtOa FeO Fe 8102 Cr:Fe 

El Corral Viejo _______________ 53.66 14.51 -------- 2.44 3. 21 

San Victor ____ --------------- 50. 68 15.34 -------- 4. 60 2.86 

Buenos Aires ____ ------------- 53.84 16.62 -------- -------- 2. 81 San Antonio no. 2 _____________ 46.07 20.87 -------- -------- 1. 91 

San Antonio no. 3 __ ----------- 49.01 17.99 -------- -------- 2.36 

La Corona no. 2--------------- 57.81 15. 11 -------- -------- 3.30 

El GuapinoL -------------- ___ 51.27 -------- 13.6 -------- 2.58 La Ceiba _____________________ 42.74 -------- 11.5 -------- 2.55 

San Pedro no. 2--------------- 50.79 -------- 16.2 -------- 2. 16 SanJuan _____________________ 54. 18 -------- 13.0 -------- 2.85 El Audiencio __________________ 40.52 -------- 14.2 -------- 1. 95 San Juancito __________________ 41. 71 -------- 15.3 -------- 1. 87 San Augustin _________________ 42.56 -------- 13.0 -------- 2.24 Ellnocente ___________________ 41. 16 -------- 11.4 -------- 2.46 La J oyita ____________________ 50.79 -------- 14. 0 -------- 2.49 
CHROMITE DEPOSITs-GUATEMALA 51 

Comparison of the analyses of ore from the two districts shows 

that the chromite of the Jalapa district has a high chromium-to-iron 

ratio and a uniformly low iron content, whereas the Cabanas chromite 

has a lower chromium-to-iron ratio, but the iron content is low in some 

samples and high in others. 

1.4.L.4.P.4. DISTRICT 

Th~ Jalapa district, about 9 miles north of Jalapa, Departamento 

de Jalapa, includes the Corona, La Gringa, and La Paz mines, which 

are major producers, and the La Esperanza, Loreto, Salvador, and La 

Independencia deposits, which ha-ve yielded small tonnages. 

The chromite deposits are in serpentine which forms the summit of 

the range lying between the Rfo Motagua valley on the north and a 

high volcanic plateau on the south. The ranges in this area rise 

to altitudes of 7,000 feet and are extremely rugged, having been deeply 

dissected by streams. Most of the deposits are on the southern flank 

Qf the range, at altitudes of 5,500-6,500 feet, but 2 of them are at lower 

elevations on the northern flank of the range. 

LA GRINGA MINE 

The La Gringa mine is in the western part of the Jalapa district, 

about 7 miles north of Jalapa (pl. 5). It is in serpentine, which is 

generally blocky but has locally been highly sheared along faults. The 

principal ore body, which cropped out, is a thick lens 75 feet long and 

6-12 feet wide that strikes N. 25° W. and dips steeply northeastward. 

Several smaller lenses of ore were discovered below the surface. The 

ore is cut by several low-angle :faults which displace the contacts a 

few feet. 

The La Gringa mine is the largest producer in Guatemala. It was 

worked during World War I, but the principal production was by the 

Vanadium Corporation of America during the 1930's. In all, 5,357 

tons of ore avera.ging 52-57 percent Cr20 3, with a chromium-to-iron 

ratio ranging from 2.8 to 3.2, has been produced since 1930. 

CORONA MINE 

The Corona mine is 2 n1iles east of the La Gringa deposit, in the 

southern part of the Jalapa· district (pl. 5). The ore bodies consisted 

of several narrow lenses striking N. 65° E. and dipping-steeply southeastward. The lenses were in a shear zone and were offset by several 

~ross faults of small displacement. The largest ore body mined was 

120 feet long and,. at the northeast end, extended to a depth of 40 

feet below the outcrop; its width ranged from 3 feet on the southwest 

to as much as 6 feet on the northeast. 

The deposit is now completely mined out, and only a large pit and 

underground workings in barren serpentine were accessible in 1944. 

The mine produced 3,465 tons of ore averaging 52-56 percent Cr20 3, 
52 MINERAL DEPOSITS OF CENTRAL AMERICA 

with a chromium-to-iron ratio ranging from 3.45 to 4.2. Some shipments are said to have contained as much -as 62 percent Cr20s. 

LA PAZ MINE 

The La Paz mine is about 2 miles northwest of the La Gringa mine~ 

on the ridge southwest of Quebrada de los Magueyes which forms part 

of the Finca (Ranch) Incienso (pl. 5). The workings are at an 

altitude of about 5,400 feet. 

The; La Paz no. 1 ore body strikes N. 60° W. and dips 60°-70° NE. 

The workings were caved when seen in 1944, and the Qriginal·dimensions of the ore body could not ·be ob"tained. '·Production during 

World War I amounted· to 491 tons of ore·averltging 58.00 percent 

Cr20s, with a chromium-to-iron :ratio ranging from· 3.2 to 3.6. 

The La Paz no. 2 ore body is about· 100 feet northeastward' from and 

150 feet below the no. 1 ore body and·has· a similar strike and·dip. This 

ore· body may be a faulted segment of the no. 1 ore· body,- as the contacts of both are sheared. The no. 2 ore body, where cut in the-workings, is 8 feet thick. The ore pinches out about 30 feet above the 

crosscut level. CABANAS DISTRICT 

The Cabanas district is in a: belt of-serpentine 12 miles long and 

2-5 miles· wide that extends from the Rio Chimilapa to the village 

of San Antonio. Summits in the area rise to about 4,000 feet in altitude; the streams are deeply entrenched, and the terrain is extremely 

rugged. The mines are in. an area about 8 miles long and lh mile wide, 

about 12 miles south of the station of Cabanas on the International 

Railways of Central America. The ore is shipped on muleback from 

the mines southward to the end of a road extending 7 miles from 

Cabanas, thence by truck the remaining 5 miles to the station where 

it is transshipped to Puerto Barrios. (P. W. Guild, 1942, unpublished 

report). 

The oldest rocks of the Cabanas area are crystalline limestone, 

quartzite, hornfels, schist, and gneiss that have been mapped by 

Sapper (1937, table 6) as chiefly pre-Cambrian, although they may 

well contain units of Paleozoic age. For the most part the rocks 

strike northward and dip steeply east or west. They have been cut in 

some places by pegmatite and quartz- veins. The peridotite and dunite 

which intruded'all these rocks have been largely serpentinized; intense 

shearing and recrystallization have produced in the serpentine a schistosity that trends eastward. Dikes of andesite, dacite, and diabase, 

probably o£ Tertiary age; cut the older rocks. Southwest of the area, 

flows of basalt and silicic volcanic rocks are interlayered ·with pyroclastic rocks. 

The chromite occurs in the serpentine as· pods or lenses; the dim ensions of the sm.allest· are· measurable in inches, while· the largest al.·e 
CHROMITE DEPOSITS-GUATEMALA 53 

as much as 8 feet thick and 30· feet long. The ore bodies usually consist of massive black chromite, but in sbme the chromite is disseminated 

in a matrix of serpen inized olivine, and·a;few show a rudelynodular 

texture. Several bodes consist of disseminated ore near their periphery arid grade into massive ore near their center. Serpentine is the 

principal gangue mi eral; uvarovite is found in many deposits, and 

kammererite is foun in a few. The ore· bodies are commonly distributed as· a series o lenses along· mote· or ·less parallel zones that 

follow the shearing. The lenticular form of the original ore bodies 

has been accentuated by shearing, which has produced slickensided 

surfaces at the contac s. 

LA JOYA MINE 

'The La· J oya mine s on the west side 6f the ridge between the Rio 

Chimilapa and· Queb ada Enseiiada (pl.' 5). It is the largest producing· deposit in the istrict and up to 1944 had yielded about 500 long 

tons of ore averaging l percent Cr20 3, with-a chromium-to-iron ratio 

of 2.7. The deposit c nsists of 2 lenses of ore, striking ·N. 70° W. and 

dipping 60° SW, wh ch are separated by a layer of serpentine 2-3 

feet thick. The lens shave been 1nined for a length of about 40 feet 

and to a depth of 25 feet. In the bottom of the workings the ore 

appears to be pinchin out. 

Other deposits, ab ut half a mile to a mile southeast of' La J oya, 

include the El Pino eco, El Guapinol, Adan, and Tuno prospects, 

which all seem to be long the same eastward-trending shear zone at 

intervals of a few hu dred feet. They consist, for the most part, of 

clean ore in sheared erpentine, but all the ore bodies discovered are 

small and have yield d only a few tons to 25 tons each. 

The Don Enrique eposit nearby is composed largely of disseminated ore in schistose erpentine. A little high-grade float is scattered 

near the principal sh ws. The La Ceiba, San Pedro, Gracias aDios, 

Santa Vincenta; and abali deposits occur within a radius of 3 miles 

from the La J oya d posit. Production from these, deposits ranged 

from a few tons to 75 t ns each. 

LA CORONA DEPOSITS 

The La Corona de osits are on the· east side of the Rio Chimilapa 

valley, in the wester part of the district (pl. 5). The production 

:from the deposits am unted to about 100 tons up to. 1943, chiefly from 

boulders weathered o t of the serpentine. 

The La Corona no. 1 deposit consists of boulders of .chromite ; the 

largest is 8 by 9 by 12 feet, and several oth-ers ttre onlysl1ghtly smaller .. 

As the boulders of ch omite are underlain by '!Serpentine tb.at contains 

a little chromite, the oulders are probably not far from their· source. 

The La Corona no 2 deposit consists of several boulders of solid 
54 MINERAL DEPOSITS OF CENTRAL AMERICA 

chromite in a gully about 600 feet east of the La Corona no. 1. The 

boulders, the largest of which is 10 by 6 by 8 feet, probably rolled 

-into the gully from a nearby source. 

The La Corona no. 3, eastward from and about 250 feet above the 

La Corona no. 2, is an outcrop 4 feet long and 1 foot thick with a few 

pieces of float ore. 

Another group of deposits lies about 3 miles east of the La J oya 

deposit on a prominent ridge that trends northward between Quebrada 

Ensefiada and the Rio San Diego; on the ridge is the Los Pinos 

mining camp. 

BUENOS AIRES MINE 

The Buenos Aires mine is on the ridge half a mile east of the Los 

Pinos camp (pl. 5). Float ore extends about 150 feet down the slope, 

and excavations 6-10 feet deep at the head of the float show chromite 

fragments in sheared serpentine. About 75 tons of ore from the surface was shipped prior to 1943; analyses showed 53 percent Cr20a and 

a chromium-to-iron ratio of 2.8. Other shows of chromite have been 

found nearby, but none of them appears promising. 

SAN JUAN PROSPECT 

The San Juan prospect is on the east side of the ridge at the Los 

Pinos camp. A lens of chromite 13 feet long and 7 feet thick in the 

center has been exposed in cuts 8 feet deep on both sides of the deposit. 

At the east end another lens, 3 feet long and 1 foot thick, wedges out 

into the serpentine, and on the west end the ore body grades into lowgrade material consisting of lumps of good ore in serpentine. On 

the margins of the ore body, chromite is disseminated in serpentine. 

A pocket 50 feet to the north yielded a ton of ore. 

SAN JUANCITO PROSPECT 

The San J uancito prospect, about 500 feet northeast of the San Juan 

deposit, is a lens 15 feet long, 12 feet deep, and 4 feet wide which 

yielded a small tonnage of low-grade ore prior to 1943. Nodules occur 

at intervals in the shear zone along the strike beyond the main deposit, 

but no ore bodies of commercial size have been found. 

EL AUDIENCIO DEPOSIT 

The El Audiencio deposit, a quarter of a mile north of Los Pinos, 

shows only low-grade ore, but it contains a notable amount of the 

chromium-bearing garnet uvarovite. The ore occurs in a series of 

lenses extending more or less continuously for 150 feet along a shear 

zone striking N. 75° W. and dipping 75° NE. Some of the lenses are 

as much as 4 feet thick, although most are narrower. Most of the ore 

appears to be too low grade for metallurgical chromite. 
•CHROMITE DEPOSITS 55 

SAN ANTONIO DEPOSITS 

The San Antonio deposits (pl. 5) are 5 miles northeast of San Diego. 

These have not been exploited because of their low grade and their 

distance from the railroad, but they are said to contain reserves totaling 200 tons. 

OTHER DEPOSITS 

Other deposits in the area, including the EI Chico, Agustin, El 

Cuervo, and San Victor, have yielded 10-75 tons each. All these deposits are lenses in sheared serpentine, although some float ore was 

included in the shipments. 

PA.SASAGUAS DISTRICT 

Chromite deposits are exposed in the low hills north of the Rio 

:Motagua near Morazan in the Pasasaguas district (pl. 5). Several 

deposits were explored by Fred Cutworth and others during World 

"\V ar I, but no shipments were made. These deposits were examined 

Jby P. W. Guild ( 1942, tmpublished report). 

Most of the exploratory work done in the district was at the Australia mine. At the Australia no. 1 deposit, a shallow pit yielded about 

10 tons of ore which iH piled near the pit. At the no. 2 deposit, 2 pits 

about 50 feet apart have yielded a few tons of ore. At the no. 3 deposit 

an outcrop of chromite a foot in its longest dimension was noted in 

sheared serpentine. 

Chromite has been reported elsewhere in the area, but none o:f the 

deposits have been explored to any extent. Samples from some of the 

deposits have been analyzed and indicate that they are for the most 

part low in grade. o~n the whole the serpentine area north of-the Rio 

Motagua appears to contain few chromite pods, and since the area. is 

well inhabited and probably already explored, the outlook for the dis~ 

eovery of large ore bodies is not promising. 

EL RETIRQ DISTRICT 

TheEl Retiro district is 10 miles north of Salama, in the hills west 

.of the Salama-Cohan highway (pl. 5). The deposits are on the Finca 

El Retiro of Adan Morales at La Cebadla. ' 

The deposits are in the middle o:f the serpentine belt, which here is 

.about 12 miles wide. Chromite is exposed on the surface in massive 

serpentine in three nreas. No exploratory work has been do~e at 

depth; but the exposures indicate that chromite is present over an :area 

-of about 100 square feet. Analyses of the ore show 48-51 percent C~zOs 

.and a chromium-to-iron ratio of 2.75. As the deposits_·a~ 50 rn:lles 

from the nearest railroad shipping point, they (1ould · :tlot be' "Wo:tk~d 

profitably during World War II. · 

1 

- i ' • :, ., .::: \

1 

388364-57-5 
56 MINERAL DEPOSITS OF CENTRAL AMERICA 

COPPER DEPOSITS 

Copper production in Central America has been principally as a 

byproduct of precious-metal mining and consequently has been small. 

The Rosita mine in Nicaragua has notable reserves, however, and may 

be put into large-scale production at some future date. 

GUATEMALA 

SAN MATEO PROSPECT 

The San Mateo prospect is half a mile south of the village of San 

Mateo Ixtabin, Departamento de Huehuetenango, and about 51 miles 

north of the town of Huehuetenango. A highway passable for light 

trucks throughout the year extends from Huehuetenango northward 

to Tojquiaj, a distance of 25 miles, and a fair trail covers the remaining distance. The property is owned by Virgilio Recinos and others 

of Huehuetenango. 

The oldest rocks in the area are mica and hornblende schists which 

have been intruded by diorite and are overlain by interbedded sandstone and shale beds of the Todos Santos formation. The copper minerals are in schist that is exposed in a stream bed on Cerro Bob! at an 

altitude of 8,300 feet. Here the schist strikes westward and dips 

steeply. The copper ore is in a shear zone that strikes N. 15° W. and 

dips northeastward. A diabase dike about 2 feet wide follows the footwall of the shear zone for about 20 feet. 

The vein minerals are pyrite, specularite, and chalcopyrite, in a 

gangue of crushed and silicified schist. The chalcopyrite occurs in 

pockets and veinlets which replace the pyrite and specularite. The 

vein is 6-18 inches wide and can be traced for 30 feet along the strike. 

An adit 20 feet long has been driven into the schist just above the vein 

outcrop. The material on the dump is schist impregnated with pyrite, but as the vein is covered with veget31tion and soil beyond the 

stream bed, its total length is not known. 

Shows of copper reported to be in nearby streams were found to 

consist of schist impregnated with pyrite. Quartz-pyrite-epidote 

veins locally cut the rock, but none were found that contained copper 

minerals. 

MATAQUESCUINTLA MINE 

The Mataquescuintla copper-silver mine is about 45 miles southeast 

of Guatemala City and 2% miles southeast of the village of Mataquescuintla. The workings are on the west slope of the Sierra de 

Mataquescuintla at an altitude of 5,500-5,700 feet above sea level. The 

property in 1943 was owned by Mr. E. W. Crowe of Guatemala Ci·ty 

(Lemus, 1917, p. 960). The deposit has been worked on a small scale 

since 1694. Jesuit priests are reported to have mined oxidized ore 

shoots for silver until 1871. In 1885 a 20-stamp mill was installed 
COPPER DEPOSITS-GUATEMALA 57 

by Conde and Cabarrus, and its production in the 2 years followingis reported to have been 40,000 ounces of silver. Since then, owner-. 

ship of the mine has passed through many hands, and the-production 

has been small. The W estend Consolidated Mining Co. explored ~h~ 

property in 1917 and 1918. . 

The rocks are volcanic tuffs and intercalated rhyolite and andesite 

flows of Tertiary and Quaternary age. The ore deposit is in silicified 

rhyolite tuff, which is cut by veins chiefly of pyrite with a little chal-. 

copyrite and chalcocite and scattered grains of galena. The veins 

are mostly less than 4 inches wide, but a few are as much as 1 foot 

wide, and at vein intersections masses of sulfides as much as 3 feet 

wide have been found. The veins are erratically distributed throughout the rock and are generally several feet apart. The silicified tuff 

between the veins is impregnated with pyrite and sparse chalcopyrite. 

The workings, although partly caved, indicate that the mineralized 

block is about 150 feet wide, 600 feet long, and at least 475 feet thick; 

the block trends northeastward and is bounded laterally by fracture 

zones. Not all of this block can be considered commercial ore, how~ 

ever, for it contains some low-grade ore and barren ground. The ore 

is oxidized to a depth of about 100 feet. Much of the pyrite has been 

leached, but some copper has been redeposited as malachite and 

chrysocolla. The ore below ·the oxidized zone is highly pyritic. 

The ore reserves are not known, but a considerable tonnage of material containing about 2.5 percent copper and 10 ounces of silver to 

the ton could be selectively mined from the area explored by the present workings. Further exploratory work would be needed to block 

outtheore. 

LOS SANDILLALES PROSPECT 

The Los Sandillales prospects are 2:fh miles south of the town o£ 

Chiquimula, .on the property of Cecilia v. de Cuellar. The workings 

are shallow cuts in granodiorite. which explore a quartz vein about 2 

feet wide. The vein strikes northward and dips steeply westward, and 

can be traced for about 50 feet. The quartz contains iron oxides, with 

veinlets and pockets of malachi·te and azurite that were probably 

formed by the oxidation of chalcopyrite. The ore is estimated to 

contain 3-5 percent copper. 

ZUHOJ DEPOSITS 

The Zuh6j deposits are 7 miles southeast of Cahab6n, in the Departamento de Alta Vera paz, on the Rio Oxek at an altitude of 800 

feet. A trail extends from Cahab6n to within 11h miles of the prospect, and the remaining distance must be covered on foot. The property can also be reached by trail from Sepcuyte, 12 miles to the south. 

The oldest rocks in the area are mica schist and hornfels which 4a:ve 

been intruded by diorite and serpentine; these rocks are overlain by 
58 MINERAL DEPOSITS OF CENTRAL AMERICA 

limestone and dolomite of the Cohan formation and by sandstone, 

shale, and congl9merate of the Sepur formation. 

The vein is in the hornfels and follows a fault zone that strikes N. 50° 

W. and dips 55° SW. The ore mineral is chalcopyrite, with pyrite 

and quartz. A little malachite coats the chalcopyrite at the outcrop. 

The chalcopyrite occurs in veinlets and pockets within the shear zone 

and is also disseminated throughout the crushed hornfels. The vein 

crosses the Rio Oxek; on the south bank it can be traced for 50 feet, 

but only boulders show on the north bank. Soil and heavy vegetation conceal the vein on the slopes above the river. A chip sample 

taken from the outcrop on the south bank assayed 12.7 percent cop· 

per and 0.03 ounce of gold and 1.1 ounces of silver to the ton 

Further exploration along the strike of the vein will be needed to determine whether the property warrants development. 

CERRO VIVO PROSPECT 

The Cerro Vivo copper prospect is on the Rio de las Vacas, abOut 2 

miles southeast of the town of Chinautla. Two adits, 45 and 80 feet 

long, and some shallow pits explore copper shows along eastwardstriking faults in diorite. The fault fissures contain calcite and iron 

oxides and scattered grains of chalcopyrite, which is partly altered 

to malachite and azurite. Further exploration does not appear 

warranted. 

OTHER DEPOSITS 

Copper deposits are also found near Trapiche Grande, Departamento de Baja Verapaz, a village about 30 miles north of Guatemala 

City. They are on the Fincas El Tamarindo, Santa Barbara, and 

El P6rvenir. 

The Tamarindo deposit is 21;2 miles northeast of Trapiche Grande. 

A short adit, which was caved in 1943, is in altered serpentine that 

contains a few calcite veins stained with malachite. Grains of a sulfide, probably chalcopyrite or bornite, are sparsely disseminated 

throughout the calcite. The material is too low in grade to be mined. 

Three shallow pits in andesite 2 miles east-northeast of Santa Barbara expose narrow veins of malachite and azurite in fractures. Half 

a mile northeast of these shows are others, also in and~ite, but these, 

too, appear to be of low grade. 

At the Finca El P6rvenir a 30-foot shaft was sunk on malachite 

and azurite outcrops, but the results were not promising. 

HONDURAS 

The following descriptions of copper deposits are based on examinations made largely by P. W. Hyde, formerly exploration geologist 

with the New York and Honduras Rosario Mining Co. Mr. Hyde 
COPPER DEPOSITS-HONDURAS 59 

visited most of the known deposits and his reports were made available to the authors by the company. 

EL AMATILLO PROSPECT 

The El Amatillo prospect is about 2 miles southwest of the Finca 

Valladares, which lies about 6 miles southwest of the village of Ojojona, Departamento de Tegucigalpa. Several short adits, spaced 

400-500 feet a.part, explore shows of copper and manganese. Two 

adits to the west show only a few copper stains, but a third shows 

pockets of copper carbonates along fractures that strike N. 70° E. and 

dip 50° SE. 

Manganese oxides are found with the copper minerals in some of 

the workings. Most of the material is low grade and siliceous. A 

knoll to the east is capped with manganese oxides; the outcrop is about 

600 feet long and as much as 150 feet wide. A sample taken from 

surface material by Hyde 2 contained 24.39 percent manganese and 

3.1 ounces of silver per ton. He thought it likely that the material 

would decrease in manganese content with depth. 

PETOA DEPOSITS 

Copper deposits near Petoa, Departamento de Santa Barbara, are 

about 30 miles southwest of San Pedro Sula (pl. 1). An improved 

road extends from San Pedro Sula to San Francisco, but the last 4 

miles to Petoa are unimproved and may be impassable during some 

parts of the rainy season. The principal copper deposits are on Waller Hill, about a mile east of Petoa, and can be reached over a steep 

trail. The deposits have been known since colonial days. Some small 

high-grade pockets were mined during the 19th century, and the cop· 

per was used in the local manufacture of bells. Guy R. Molony denounced the property in 1926, and in 1942 the United Fruit Co. did 

a little exploratory work there under the direction of A. L. Bump, but 

no ore was shipped. . 

The copper deposits are in limestone and shaly limestone near contacts with diorite porphyry. The limestone exposed in the workings 

appears to strike northwestward and to dip gently northeastward. 

The copper minerals include chalcopyrite, azurite, and malachite. 

Chalcopyrite was seen in only one place, the Santo Domingo shear 

zone; elsewhere the ere has been completely oxidized. . 

The Santa Ines workings consist of several trenches and an adit at 

an altitude of about 1,500 feet on Waller Hill. The top of the hill is 

silicified limestone stained with iron oxides. Small pockets of copper 

ore are scattered throughout the limestone, but on the whole the mate-· 

rial is low grade. The underground workings, about 25 feet below 

• Hyde, P. W., 1942, Report to New York and Honduras Rosario Mining Co., San J'uancito, Honduras. 
60 MINERAL DEPOSITS OF CENTRAL AMERICA 

the summit, explore a gently dipping shaly limestone bed which contains sparse copper carbonates. 

Several shallow empire-drill holes along the diorite porphyry contact east of the Santa Ines workings in the 1930's revealed only lowgrade or barren rock. 

The Los Mangos workings, which are about 800 feet east of those 

on Waller Hill and about 300 feet lower, consist of several shallow 

pits and a trench about 15 feet deep. A vein of quartz and copper 

carbonates 1-2 :feet wide which strikes N. 60° W. and dips 65° SW. 

is exposed in the trench but has not been explored beyond it. 

The Santo Domingo workings are about 1,000 feet east of the Los 

_Mangos workings, on the banks o:f the Rio Tascalapa. The workings 

are 3 shallow pits along a shear zone striking N. 25° E. in limy argillite and limestone. Locally the shear zone contains small veinlets and 

pockets of chalcopyrite and malachite. 

Shows of copper near Petoa are widespread, but exploratory work 

up to 1944 had disclosed only small low-grade ore bodies, which do not 

appear promising. 

MACUTLA PROSPECT 

-The Macutla prospect is about 2112 miles southwest o:f Petoa, on the 

west bank of the Rfo Macutla. The rocks in the area are diorite, porphyry, and limestone; tactite has been formed in places along contacts 

between these rocks and is accompanied by shows of copper. An 

adit 25 feet long has been -driven along a vertical 50-foot-wide fracture zone that trends westward and contains pyrite, chalcopyrite, 

sphalerite, and specularite and other iron oxides. The :fracture zone 

could be traced westward :for 350 feet from the workings. Assays of 

the vein material show a copper content averaging about 2 percent, 

with 0.016 ounce of gold and 0.78 ounce of silver to the ton. 

LOMA CHAMUSCADA DEPOSIT 

The Lorna Chamuscada copper-zinc deposit is 5 miles by trail south 

of Nispero, Departamento de Santa Barbara. The rocks are red to 

buff sandstones which in general strike eastward and dip about 55° S. 

Thin seams of chalcopyrite, pyrite, and sphalerite are present in the 

sandstone. At one place a stringer zone 3-4 feet wide parallels the 

bedding, which strikes N. 85° W. and dips 75° S. The copper content 

of samples collected by Hyde 3 ranges from 1.0 to 3.6 percent and the 

zinc content from 4 to 12 percent. 

LAS CHACARAS MINE 

The Las Chacaras mine is a mile east of Comayagua, Departamento 

de Comayagua, on the north bank of the Rio Chiquita. The property 

is owned by Salvador Lopez of San Pedro Sula. The copper minerals 

a Hyde, P. W., op. cit. 
COPPER DEPOSITS-COSTA RICA 61 

are chiefly carbonates, with sparse chalcopyrite and galena, in a quartz 

vein that follows a fracture zone about 50 feet wide in limestone. The 

zone strikes N. 45° E. and dips 60°-75° NW. Parts of the old workings extending 600-800 feet along the vein are still accessible. Samples taken from the dump show a content of 2.8-23.9 percent copper 

and 0.98-7.58 ounces of silver to the ton, with a trace of gold. 

Other copper deposits are reported at San Rafael Parafso, about 2 

miles upstream from the Las Chacaras mine. 

SANTA CRUZ PROSPECT 

The Santa Cruz prospect is on the trail to Y oro, about 30 miles from 

Progreso, in the Departamento de Y oro. Narrow oxidized copper 

veinlets less than 2 inches wide strike N. 60° E. and dip 50° NW. A 

vein nearby, the Lagunitas, has been worked for gold and silver; 

locally it contains oxidized copper minerals. 

OTHER DEPOSITS 

Raymond M. Brown, mining engineer in Honduras, says there are 

shows of copper near Minas de Oro, Departamento de Comayagua. 

Manuel Bueso, of Santa Rosa de Copan, reports copper shows in the 

Cordillera de Merend6n, Departamento de Copan. No exploratory 

work has been done on these, but boulders of high-grade ore as much 

as 50 pounds in weight~ containing chalcocite and azurite, have been 

found. Hyde examined the shows in 1942 and reports that the rocks 

nearby are limestone and conglomerate, and that poor exposures preYent examination of the ore in place. Trenching will be needed to 

determine the source of the copper ore. 

COSTA RICA 

AGUA..CATE DISTRICT 

MONTE DEL AGUACATE MINE 

The Monte del Aguacate copper-zinc mine is in the Aguacate mining 

district, about 31h miles north of Concepcion, a station on the Pacific 

Railroad. The rocks are horizontally layered andesitic lavas, which 

are cut by banded quartz veins trending northeastward. Gold has 

been mined from these veins for many years, and in some of the veins 

there are ore shoots containing copper and zinc minerals, with manganese minerals, principally rhodonite. The known copper-zinc 

shoots are small, and none discovered prior to 1944 warranted stoping. 

However, since the amount of base metals seems to increase with depth, 

it is possible that larger shoots may be discovered in future operations. 

PURISCAL AREA 

Copper deposits have been known for many years in the Puriscal 

area near the villages of Guayabo and San Rafael, Provincia de San 
62 MINERAL DEPOSITS OF CENTRAL AMERICA 

Jose. The rocks in the area are andesitic and basaltic lavas that commonly are nearly horizontal but are locally folded and have dips as 

steep as 30°. 

GUAYABO DEPOSITS 

The Guayabo deposits are about a mile southwest of Guayabo. . The 

copper occurs as thin sheets of native copper that fill fractures in the· 

lava; the sheets average about one thirty-second of an inch in thickness, 

and some are as much as a square foot in area. The shows are ~xposed 

for about 125 feet in a stream cut, and placer copper can be panned 

from gravels for about 1,500 feet downstream from these exposures. 

The sheets are commonly 6 inches to several feet apart, and the grade 

of the ore in place is judged to be low, probably not more than 1-3 

percent copper even in the richer areas, and probably averages less 

than 0.2 percent. On the slopes a heavy soil mantle covers the outcrops. 

SAN RAFAEL DEPOSITS 

The San Rafael deposits are about a mile northwest of San Rafael. 

Here also there are thin sheets of native copper in lava. The min-

.eralized zone trends northward, dips steeply westward, and is about 

25 feet wide where it is exposed in a small stream bed; as its extensions 

are covered on both sides with soil, its full length is not known. The 

fractures containing the sheets are commonl! several feet apart, and 

the material is low grade. · 

NICARAGUA· 

A copper deposit has been known for many years in eastern 

Nicaragua at Rosita. The property has not been put into production 

because of the high cost of transport of supplies, equipment, and 

concentrates. However, the higher value of copper prevailing in 

1956 may offset these high costs, and plans to begin operations were 

being considered. 

ROSITA MINE 

The Rosita mine (also known as the Santa Rita mine) is in the . 

district of Tunki, Departamento de Zelaya, about 3 miles east of the 

village of Monte Carmelo. The principal workings are on Cerro Santa 

Rita about three-fourths of a mile north of the Rfo Bambana. The 

property consists of 18 claims and can be reached by plane which lands 

at an airport 11;2 miles to the northwest. 

No copper has been produced, although between 1906 and 1912 parts 

·of the gossan and oxidized zones were mined and milled for gold. It 

is reported that 40,000 tons of ore was treated, but the production 

is not known. The Tonopah Mining Co. acquired the property in 

1916 and in 1949 sold a part interest to Ventures, Ltd.; in 1954 the 

property was acquired by La Luz Mines, Ltd. Additional exploratory 

work was done between 1951 and 1955, and mill and metallurgical 
COPPER DEPOSIT8-NICARAGUA 63 

tests were being made on the ore preparatory to installation of a treatment plant. The workings in 1942 at the time of the visit consisted 

of 23 short adits with connecting workings and 96 churn -drill holes. 

Since then additional underground workings have been driven and a 

diamond -drilling program has been carried on. 

The principal copper-ore body is on Cerro Santa Rita, which is 

largely underlain by rock composed of orthoclase, quartz and garnet. 

Huston 4 considered this rock to be intrusive alaskite, but Roberts 

in 1942 collected specimens in the workings that are nearly pure garnet 

and are considered to have been formed by metamorphism of limestone. No unmetamorphosed limestone was seen in the workings, hut 

1% miles to the north limestone is being quarried for the Neptune 

mine. The limestone, which strikes northwestward and dips steeply 

southwestward, is probably correlative with the limestone beds that 

are associated with the Metapan formation in northeastern Nicaragua 

(pl. 1). 

The ore body on Cerro Santa Rita appears to be in a contact zone 

adjacent to an andesitic intrusive body. The upper part of the ore 

body is oxidized and forms a conspicuous iron oxide gossan that according to Huston is 30-230 feet thick. The iron oxides contain disseminated malachite, azurite, cuprite, and chrysocolla. The oxidized 

carbonate ore comprises nearly two-thirds of the ore reserves known 

up to 1943 (see table below) . The lower part of the ore body is a 

sulfide zone reported to be 10-30 feet thick that is composed of pyrite 

partly replaced by chalcocite and bornite. The ore reserves calculated 

by him are summarized in the table below. 

Summary of copper-ore reserves and partial analyses, Rosita mine, Nicaragua 1 

Reserves (short tons) 

Cu (percent) Au (oz) 

Sulfide ore: High grade _____________ ------ _____ 163,556 10.29 0. 17 Low grade _________________________ 308,800 3. 37 . 013 

Total or weighted average _________ 472,356 5. 76 0.068 

Carbonate ore (oxidized zone) ___________ 984,232 4. 83 o. 03. Tailings _______________________________ 35,500 1. 97 . 13 

Grand total or weighted average ___ 1, 492,088 5.06 0.045 

1 Mines Handbook, 1920, p. 1757. 

Additional reserves discovered by diamond drilling d~ring recent 

years bring the total to 2 million tons averaging about 3.9 percent 

copper. 

& Huston, M. B .. , 1918, Report to the La Luz Mine, Ltd., Siuna, Nicaragua. 
64 MINERAL DEPOSITS OF CENTRAL AMERICA 

IRON DEPOSITS 

Iron ore is reported to occur in all the Central American countries 

except British Honduras, but no deposits have been productive on a 

large scale. Two iron-ore deposits, the Agalteca in Honduras and 

the Rosita (Silak) in Nicaragua, may be productive if transportation 

facilities are improved so that the ore can be economically shipped. 

HONDURAS 

AGALTECA DEPOSITS 

The Agalteca iron-ore deposits. are on the Finca Santa Clara, which 

is in the foothills of the northern flank of the Sierra de Comayagua, 

in the Departamento de Tegucigalpa (pl. 6). The nearest settlement 

is the village of Agalteca (approximately lat 14°30' N., and long 

87°16' W.), which lies a mile north of the mine area. Tegucigalpa, 

the capital of Honduras, is 24 miles to the south. 

The Agalteca deposits have been known for many years, but because 

of their inaccessibility no attempt has been made to work them. Some 

exploratory work has been done during the course of examinations by 

various groups including the Bethlehem Steel Co. and Gen. R. Streber 

and some associates between 1910 and 1922. For the most part the 

workings consist of shallow trenches and pits, but 2 adits, 30 and 180 

feet long, and a 70-foot shaft were driven. Philip Chase conducted 

exploratory work at Agalteca for the Oliver Iron Mining Co. in 1946. 

The results of his work have not been published. 

The deposits are remote from the principal. routes of travel and 

transportation in Honduras. A fair road extends from Tegucigalpa 

for 30 miles northward to Talanga, and a dirt road, passable during 

the dry season, from May to November, extends from Talanga for 12 

miles westward to Agalteca. A highway from Tegucigalpa to 

Potrerillos is the route along which most of the freight moves from 

the north coast of Honduras to Tegucigalpa. This highway passes 

through Comayagua, 18 miles west of Agalteca, but construction of a 

connecting road through the rugged country between it and the deposits would be difficult. The most favorable route for shipment of 

ore would be down the Rfo Sulaco to the railroad at Potrerillos, which 

extends to the principal Caribbean shipping point, Puerto Cortes. 

From Puerto Cortes ore could be transshipped to United States ports. 

Geology 

The Sierra de Comayagua trends northwestward across the central 

part of Honduras. The lowest altitude within the range is 2,400 feet, 

at the Finca Santa Clara in the foothills, and the highest is about 

6,500 feet. On the summit and southwest flank the rocks are Tertiary 

lavas and pyroclastic roc~s that dip gently southwestward. On the 
IRON DEPOSITS-HONDURAS 

northeast flank the rocks are older and partly covered by Quaterna-ry:· . 

sand and gravel; these older rocks contain the iron ore. 

The rocks on the north flank of the range in the area mapped (pl. 6) : 

consist of five principal units. In order of age they are ( 1) quartzite; . 

( 2) conglomerate and sandstone, and limestone, dolomite, and shale; · 

(3) diorite which intrudes rocks of unit 2; (4) rhyolite dikes; and · 

(5) Tertiary and Quaternary sand and gravel which overlie the older · 

rocks. Except in the higher parts of the area mapped, exposures are 

poor and the slopes are mantled by soill-20 feet thick. Test pits were 

dug in many places to determine the location of contacts, particularly 

along the borders of the ore bodies. 

The quartzite crops out northwest of the ranch near ore body Q 

(pl. 7). As the quartzite is in fault contact with hornfels on one side . 

and is overlapped on the other sides by Quaternary gravel, its relation 

to the other rocks is not definitely known; but as the quartzite is more · 

highly indurated and deformed than the other rocks in the area; it 

is probably older and may be of Paleozoic age and correlative with · · 

crystalline rocks exposed elsewhere in northern Honduras. 

The conglomerate and sandstone crop out in a small area between 

the groups 0 and C ore bodies and on the slope south of the area 

mapped (pl. 6). They are composed of poorly sorted detritus and 

are commonly reddish brown to brown because of their iron oxide · 

cement. The pebbles of the conglomerate are chiefly sandstone, 

quartzite, and quartz, with a minor amount of schist, phyllite, and 

limestone. 

The conglomerate and sandstone are conformably overlain by lime- : 

stone, dolomite, and shale. At the contact the 2 units interfinger in; 

a transitional zone that is generally less than 30 feet thick. The 

limestone and dolomite are thick bedded to massive for the most part, · 

but where they are intercalated with shale and limy shale they are thin ' 

bedded. This unit has been intruded by diorite and has been meta"' : 

morphosed to hornfels and tactite, which contain the iron-ore bodies.'· 

No fossils have been found in either the conglomerate and sandstone 

unit or in the limestone, dolomite, and limy shale unit, but elsewhe~e 

in Honduras similar rocks contain fossils of early Late Cretaceous · 

age and are correlated with the Metapan formation. These rocks'are I 

therefore assigned to the Metapan formation. 

The diorite underlies much of the area mapped. It is exposed in , 

all the valleys that drain the area, and although outcrops are poor . 

on the slopes, pits have disclosed diorite close to the ore in severaL 

places. The diorite is 'fine to medium grained, light tQ dark gray •• I 

and is composed chiefly of hornblende and plagioclase; it weathers·: 

to a yellow· or brown clayey soil. The diorite cuts limestone, dolomite,,r 

and shale which have been metamorphosed to tactite and hornfelS ne~t : 
66 MINERAL DEPOSITS OF CENTRAL AMERICA 

the contacts and in roof pendants in the diorite. The tacite, formed 

by the metamorphism of limestone and dolomite, is moderately to 

coarsely crystalline and consists chiefly of garnet, epidote, hornblende, 

calcite, and plagioclase. The hornfels, formed by the metamorphism 

of shale and calcareous shale, is commonly fine grained and is composed of epidote, quartz, calcite, garnet, and hornblende. A few small 

ore bodies are found in the limestone and dolomite, but most of the 

ore occurs in the hornfels and tactite. These rocks are altered near the 

ore bodies to a brown or yellow clayey soil, which in some places cannot readily be distinguished from soil derived from diorite; usually 

a pit must be dug in order to definitely identify the bedrock. 

The rocks in the foothills of the Sierra de Comayagua have been 

compressed into folds with a northwestward trend and plunge. The 

folds generally appear to be open, but are locally tight and in a few 

places overturned. 

Three sets of faults have been mapped in the area (pl. 6) : one 

of them trends northwestward, parallel to the folds; another trends 

northward, cutting the folds diagonally; and the third trends northeastward, normal to the folds. Movement on these faults has caused 

repetition of the beds throughout the area ; the displacements range 

from a few feet to several hundred feet. Some of the ore bodies 

have been cut by faults and are displaced, but so far as is known these 

displacements are small. It is therefore inferred that most of the 

faulting took place before formation of the ore bodies. 

The ore bodies crop out in the foothills of the range south and west 

of the Finca Santa Clara, and, as most of the ore is more resistant 

than the associated rocks, the ore bodies generally form ridges rising 

a few feet to 200 feet above the surrounding area. Plate 6 shows the 

general distribution of the ore bodies. The ore bodies are tabular, 

lenticular, or irregular masses of iron oxides, mainly in the hornfels 

but partly in tactite and limestone. In some places the ore has replaced 

these rocks along the bedding, but generally the ore cuts the bedding; 

in detail the contacts are irregular. 

Hematite and magnetite are the principal ore minerals; the proportion of these minerals is variable, but commonly the hematite predominates. It is thought that the hematite may have been in part 

formed by oxidation of the magnetite near the surface. The magnetic 

variety of magnetite, commonly called lodestone, is present on the 

southeast end of group 0. Pyrite is a minor constituent of the ore; 

veinlets of pyrite in hornfels were noted in a trench on the north end 

of group B and in samples collected from tlie adit driven into the 

group C ore body. The ore is principally hard, tough iron oxides 

which form craggy outcrops, but locally this ore is weathered and is 

altered to soft, earthy material which forms smooth slopes. Where the 
IRON DEPOSITS-HONDURAS 67 

· ore is of the latter type, test pits are generally needed to prove whether 

a slope is underlain by soft ore or hornfels. 

The ore exposed in the outcrops and workings at Agalteca is for the 

most part of good grade; the iron content in almost all of it is between 

40 and 66 percent and averages about 53 percent. The phosphorus 

content ranges from 0.010 to 0.082 percent and averages about 0.037 

percent, and the sulfur content ranges from 0.005 to 0.058 percent, with 

an average of 0.020 percent. The amount of silica in the ore is variable,. 

ranging from 3.5 to 39 percent, and averages less than 10 percent in 

samples cut from surface trenches. It is quite likely that the low 

silica content of the ore on the surface is due to leaching, and th6 

average silica content at depth may be found to be considerably higher. 

The alumina content of the ore is commonly below 2 percent, and the 

manganese content is between 0.01 and 0.28 percent. 

The underground workings show that the ore bodies locally contain 

layers and masses of low-grade ore formed by incomplete replacement 

of the host rock; this ore is generally softer than the high-grade ore 

and could probably be discarded in mining. In this way the grade of 

ore mined could be increased, possibly to 55 or 56 percent iron. 

More than 35 ore bodies have been mapped in the area; about 20 of 

the larger ore bodies were mapped in detail. These are designated on 

· plate 7 as groups P, 0, Q, C, and B. 

The ore bodies range from a few feet to 1,100 feet in length, and 

some are as much as 350 feet wide. The maximum depth of the ore 

is not known, but at group C the ore is exposed over a vertical range 

of at least 200 feet, and at group B, 230 feet. 

The workings that explore the ore bodies are for the most part shallow; however, 2 adits, 40 and 180 feet long, have been driven, and these 

furnish valuable information concerning the ore below the surface. 

Group P 

The main part of group P (pl. 7), which crops out on a ridge 5,000 

feet southwest of the Finca Santa Clara buildings, is chiefly magnetite 

and hematite which replace hornfels and limestone. It is 480 feet long, 

260 feet wide, and about 120 feet thick. On the west it is probably cut 

off by a fault, for it ends abruptly against tactite and limestone. On 

the east this ore body pinches out, but other lenses continue on the same 

strike. 

The northwest side of a trench across the deposit shows ore of good 

grade (samples 44, 49, 59, and 67), intermixed with some clayey ore, 

but on the southeast side of the trench the ore is low grade and encloses 

considerable hornfels. The chip samples (11 and 59) weretaken.along 

the outcrops. (See table below.) 

A lens of low-grade ore as much as 25 feet wide crops out ea.St 6f 

. the main ore body. This lens appears to dip southward, parallel to the 
68 MINERAL DEPOSITS OF CENTRAL AMERICA 

dip of the limestone nearby. Other ore bodies occur on the ridge to the 

south and west of group P, but they are all small. 

Partial analyses of iron ore from the group P ore bodies, A.galteca deposit, 

Honduras 

[Birger Sundstrom, Mexico City, Mexico, analyst] 

Sample Fe p s Mn AbOa 'Si02 CaO MgO Ti no. 

u _____ 64.55 0.023 0.037 0. 11 0. 28 5.99 44 _____ 61. 84 . 021 . 010 49 _____ 65.06 . 009 . 058 . 01 . 05 3. 93 ------ ------ ---- 59 _____ 61. 98 . 024 . 038 67 _____ 61. 38 . 014 . 013 

Group Q 

Group Q is 4,500 feet northwest by west of the Finca Santa Clara 

buildings, on a low ridge west of the Rfo Aguacate (pl. 7). It is in 

hornfels, but diorite shows in the stream valley south of the ore body, 

and Quaternary gravel overlaps the diorite and ore on the west. On 

the north and east, quartzite is in fault contact with the hornfels that 

.encloses the ore. Tuff overlaps the fault in the valley. 

The ore body is. e~o~ed more or less continuously for a length of 

1)00 feet along the ridge and has an average width of about 75 ·feet . 

.A trench showed ore of good grade (samples 47 and 48, table below) . 

.Although the roof pendant of hornfels containing the ore may extend 

to a considerable depth, the presence of diorite so close to the outcrop 

is not encouraging, and the ore cannot be projected more than 50 feet 

below the surface. 

·Partial analyses of iron. ore from the group Q ore bodies, A.gtllteca deposit, Honduras 

[Birger Sundstrom, Mexico City, ME)xico, analyst] 

Sample no. Fe P S 

41-------------------------------------------- 64. 12 0. 030 0. 016 

' 48-------------------------------------------- 63. 75 . 013 . 005 

, GrO'P.P B 

Group B is 2,000 feet west of the ranch buildings (pl. 7). The 

principal outcrops are on a ridge trending northwestward, and others 

. are found southwest and northwest of the ridge. The enclosing rock 

, is hornfels, but diorite is exposed nearby in two pits and in the stream 

: valley southwest of the ridge. 

·The principal ore body is 750 feet long, as much as 160 feet wide, and 

is exposed vertically for 230 feet. It is explored by shallow trenches 

. ·and a short adit, which shows fair--grade ore that is locally siliceous. 

~·: .... Another qre body, 80 feet wide and 180 feet long, lies to the· north. 
IRON DEPOSITS-HONDURAS 69 

The ore, exposed in a long trench, is of fair grade, siliceous, and locally 

contains a little pyrite. An adjoining area, mapped as landslide ore, 

is ore that has slumped from the main body. 

The slopes around group B are mantled with a few inches to 5 feet 

or more of slope-wash ore. ·Two test pits were dug to a depth of 3 feet 

in this material; 1 pit yielded 17 pounds of ore per cubic foot, ~ the 

other 32 pounds per cubic foot. Similar yields appear likely in other 

parts of the area covered by such slope wash. 

Partial analyses of samples from group B are described in the table 

below. 

Partial analyses of iron ore from the group Bore bodies, Agalteca deposit, Honduras 

[Birger Sundstrom, Mexico City, Mexico, analyst] 

Sample no. Fe 

39__________________ 57. 85 

40--- --------------- 61. 22 41__________________ 53. 52 

42- - - -------- - --- - - - 45. 26 

43- - - - - - - - - - - - - - - - - - 63. 07 

45------------------ 53. 00 

50--- --------------- 59. 13 5L _ _ _ ___ ____ _______ 63. 33 

60- - - --------------- 64. 25 

Group C 

p 

0. 055 

. 052 

. 041 

. 042 

. 021 

. 022 

. 017 

. 019 

. 041 

8 

0. 029 

. 041 

. 030 

. 018 

. 010 

. 050 

. 006 

. 017 

. 035 

Mn AbO a SiOt 

-------- -------- -------- -------- -------- -------- -------- -------- -------- 0.06 2. 99 26.12 

-------- -------- -------- -------- -------- -------- -·------- -------- -------- . 05 . 07 3. 93 . 23 1. 14 5. 04 

Group C is about 3,500 feet northwest of the ranch buildings (pl. 7). 

The ore is in hornfels, but tactite is exposed in the southwestern part 

of the area, and a small outcrop of limestone was mapped in the southeastern part. 

There are two principal ore bodies. Ore body 1, the northern of the 

two, is 900 feet long and as much as 350 feet wide, and it crops out 

vertically for 200 feet. It has been explored by shallow trenches, 

shafts, and an adit 180 feet long. The trenches on the west side of 

the outcrop show ore through a vertical distance of 55 feet. Although 

the trenches cut the contact of ore and hornfels in several places, the 

contact is not well exposed. The contact is commonly gradational, 

locally sheared, and in general appears to dip steeply. The adit at 

the northeast end of the deposit shows a good cross section of the ore 

for a distance of 180 feet. Samples cut along the walls indicate that 

the grade is variable, and the ore is too lean on the average to be 

mined as a single ore body, so that selective mining or concentration 

will be necessary. The ore near the portal is low grade and siliceous, 

fair-grade material occurs at the bend, and the ore at the face is high 

grade. This adit gives an idea of the probable variation in conlposition to be found in any marginal facies of these ore bodies. (See table 

below.) 
70 MINERAL DEPOSITS OF CENTRAL AMERICA 

Ore body 2 is 280 feet long and 170 feet wide at the widest point. 

It caps a small hill and appears to be relatively thin. 

Partial analyses of iron ore from the group C ore bodies, 4.g~lteca deposf,t, Honduras 

[Birger Sundstrom, Mexico City, Mexico, analyst] 

Sample no. Fe p 8 Mn AhOs Si02 CaO MgO Ti 

-...;-----~1----1-----------------

1 ___________ 58. 55 0.019 2 ___ .., _____ .,._ 3 ___________ 60. 62 . 0~4 

63.85 . 021' 5 ___________ 60. 88 . 010 6 ___________ 55.45 . 035 8 ___________ 58. 55 . 028 1Q __________ 31. 80 . 025 12 __________ 61. 65 . 030 14 __________ 31. 85 . 046 16 __________ 47. 20 . 059 17 __________ 45.45 . 059 18 __________ 59. 25 . 050 19 __________ 63.25 . 080 2Q __________ 61. 55 . 034 21 __________ 63.37 . 036 22 __________ 37.05 . 040 

23'- - - - - - - - - - 55. 65 . 048 24 __________ 50. 14 . 059 25 __________ 45. 20 . 070 26 __________ 47. 70 . 060 27 __________ 52.48 . 032 28 __________ 51.45 ·. 048 52 __________ 59. 30 . 029 53 __________ 66. 35 . 028 6L _________ 64. 55 . 036 

Groupo 

0.045 

. 019 

. 017 

. 008 

. 011 

. 010 

. 010 

. 010 

. 013 

. 010 

. 073 

. 041 

. 056 

. 015 

. 019 

. 012 

. 015 

. 015 

. 023 

. 018 

. 006 

. 036 

. 006 

. 037 

. 015 

------ ------ ------ ------ ------ ------ 0. 22 0. 48 8. 47 ,------ .. ,..---- ~-----

--:6~- -i:~~- -~:i~- -6:ii- -6:i~- -----~ 

. 06 13. 13 39. 27 ------ ------ ------

. 15 . 75 24. 91 ------ ------ ------

.06 .58 11.09 .27 .33 0 

. 06 . 05 6. 99 ------ ------ - ----- . 28 1. 28 6. 82 ------ ------ -----~ 

The ore bodies of group 0 (pl. 7) a~e 9 in nu.mber, but only 3 are· 

larg~ enough to warrant description. They are in altered hornfels; 

that is in fault contact with limestone that strikes northwestward and 

dips 30°-80° NE. The principal ore body, exposed in th.e eastern part 

of the area shown inplate~, is 440 feet long, as much as 230 feet wide,. 

and has an exposed thickness of 75 feet. A mantle of residual or~ ~xtends down the slope northwest of it; locally this mantle is 20 :f_eet 

thick, . and. aside from a little intermixed soil it is compo.~ed of i:r;oil:. 

oxide fraginents. Landslide ore extends down the slope to the north--

east and east .. · · · 

Another ore body, 200 feet to the west, is 200 feet long and 50-100 

feet wide. A trench cut in the ore and limestone on the south side 

of this ore body shows low-grade ore which has partly replaced limestone and shaly limestone. The trench on the west side shows th~tthe· 

ore grades into the hornfels down the slope. · 

A. third ore body, in .the southwestern part of the area mapped, is: 

160 feet long and as much as 120 feet wide. A long trench which. 

crosses the outcrop shows ore that is of good grade on the average, 

but it contains masses and layers of ]ow-grade material. ' 
IRON DEPOSITS-HONDURAS 71 

Analyses of samples taken from group 0 are given in the table· 

below. 

Partial analyses· of iron ore from the group 0 ore bodies, Agalteca deposit, Honduras-

[Birger Sundstrom, Mexico City, Mexico, a.na.lyst] 

SampJ,eno. p s Mn AhOs Si02 CaO MgO Ti 

-----1·---1------------------

. . 

.29~---- 30 _________ -----_ 31 _________ _ 32 _________ _ 

33 ________ :._ 

34 _________ _ 

35 _________ _ 36 _________ _ 37 _________ _ 46 _________ _ 

57. 46 0. 062 0. 014 

63. 12 . 087 .. 009 

64. 62 . 058 . 011 

{)9. 53 . 051 . 004 

54.38 .047 .009 

57.58 .023 .010 

62.70 .011 .003 

65. 93 . 025 . 013 

61.98 .039 .017 

60.27 .050 .010 

0. 12 1. 51 12. 92 0. 32 0. 41 ------

. 03 . 25 8. 02 ------ ------ --,-,---

RESERVES .AND OUTLOOK FOR .ADDITION .AL DISCOVERIES 

A general idea of the surface extent of the ore has been obtained by 

trenching. Preliminary calculations indicate that about .8 million 

long tons of ore averaging about 53 percent iron may be expected in 

the ore bodies exposed i.n the A.galteca area between the surface and a 

depth of 200 feet. There is no reason why ore cannot extend to greater· 

depth as the ore is in roof pendants of hornfels and limestone, which 

may well extend below the average altitude of the top of the diorite· 

body. In addition, some ore bodies may now be concealed by alluvium 

or barren rock; a. program of prospecting by magnetic methods could 

be undertaken to determine whether the district contains any such 

buried ore bodies. In addition, exploratory work should be extended 

into adjacent areas covered by younger rocks. 

ARA:MECINA DEPOSITS 

Small deposits of iron ore are found 3 miles east of A.ra.mecina,. 

Departamento de Vaile, Honduras, on the south slope of Cerro Colorado at an altitude of 2,600 feet. Granodiorite, the principal bedrock 

in the area, is the host rock of the iron ore. The hills south of Cerro 

Colorado consist of Tertiary lavas and tuffs. 

The iron ore is intergrown magnetite and hematite and forms a. 

lenticular body in the granodiorite. The lens strikes north and appears to dip steeply. 'It is about 30 feet long, as much as 10 feet 

wide, and is exposed for a vertical distance of about 15 feet. The 

ore in the central part of ·the lens appears to be nearly pure iron 

oxide, but near the edges it contains unreplaced inclusions of granodiorite and crystals of feldspar and quartz. 

Other deposits of iron ore are reported in the area, but accounts 

indicate that they, too, are small. 

888364-57-6 
72 MINERAL DEPOSITS OF CENTRAL AMERICA 

NICARAGUA 

ROSITA AREA 

Iron ore is reported to occur in a belt 40 miles long extending southeastward from a point east of Pis Pis to the lowland of the Rio 

Songuas, a tributary of the Rio Bambana. In the vicinity of the 

Rosita copper mine, iron deposits of commercial size, low in phosphorus and sulfur and with an iron co1.<tent of as much as 65 percent, 

are reported (Garbrecht, 1920, p. 791-797). The ore bodies occur 

along contacts between limestone and intrusive diorite. As none of 

them have been explored, the tonnage of ore is not known. Some of 

the outcrops cover as much as 10 acres, and the outlook for developing commercial iron-ore reserves seems promising. 

OTHER AREAS 

Iron ore is also reported in the Boaco area, Departamento de Chontales, about 45 miles northeast of Managua. Ore samples from the 

area consist of siliceous specular hematite. The deposits are said to 

replace quartzite beds. Magnetite has been reported from the Achuapa area in the Departamento de Leon. 

GUATEMALA 

Iron•ore' ·deposits ·are reported in· several·: areas near Chiquimula, 

Departamento de Chiquimula. Of these deposits only 1, at El Pante6n 

de San Jose de Arada, 5 miles south of Chiquimula, was visited. The 

iron ore is hematite, which forms veins in limestone. The ore appears 

to be of good grade, but because of soil cover the ex·tent of the deposit 

was not determined. 

Other localities where deposits are reported are at El Moral, on 

the'"west side of the Oordi]ilera del Sauce, where float boulders in:seil 

were being mined on a ·smaJl scale in 1945 by Alejandro Synegub ·for 

use in the cement industry; the Finca Las Minas, on the property of 

Cecilia v. de Cuellar, near the summit of the Cordillera del Sauce; El 

Chanco, 2 miles south of Cerra de Ticanlu, on the road from Chi quimula to Olopa, where ore is said to occur as float boulders in soil; El 

Tituque, 31;2 miles northwest of Olopa; and Camotan, between the 

village of Camotan and the Honduras border. 

Although none of these deposits may contain a large tonnage of iron 

ore, their nearness to the railroad which passes through Chiquimula 

makes them attractive to operators using the ore locally and to manufacturers who need small quantities of ore. 

COSTA RICA 

Iron-ore deposits have been reported near San Ra1n6n, in Costa Rica. 

The deposits have not been explored and the reserves are not known, 

but the ore is said to be of good quality. 
MINERAL DEPOSITS OF CENTRAL AMERICA 

-LE-ADr-ZJNC DEPOSITS 

GUATEMALA AND EL SALVADOR 

73 

The A.lotepeque and Metapan districts of Guatemala and El Salvador are near the junction of these countries and Honduras. They 

are in an area of Cretaceous rocks, which is surrounded by Tertiary 

_volca:nic rocks. The two districts are .described together, as their ore 

deposits and general geology are similar. 

GEOLOGY 

The rocks in the area belong to four main groups. The oldest group 

includes interbedded shale, sandstone, conglomerate, and limestone 

which belong to the Metapan formation of early Late Cretaceous age. 

These r:ocks have been intFuded by small bodies of diorite and qaartz 

Inonzonite, and both the Sedimentary and the intrusive rocks are overlain by volcanic rocks of Tertiary and Quaternary age. ·The youngest 

is the alluvium, of Quaternary and Recent age. . 

The Metapan formation was named by Sapper (1937, p. 65; Miillerried, 1942a, p. 129) from exposures in this area. This formation is 

described earlier in this report, but may be summarized briefly as 

consisting n1ainly of red shale, sandstone, and conglomerate with interbedded layers-of·limy.shale andlimestone. 

East of Metapan, on the peaks of El Sill6n and at other places 

throughout the area, the youngest rock unit is a massive limestone bed 

100 feet or more thick which is distinguished in plate 8 as the limestone unit of the Metapan formation. The upper part of the section 

has been eroded, and the Metapan strata are overlain by pyroclastic 

rocks and lavas of Tertiary and Q,uaternary age. 

The · Metapan formation is cut by diorite, quartz monzonite, and 

granodiorite which occur as dikes, sills, and ·small intrusive'ml\>sses. 

These rocks are generally'· fine to medium grained, but in places the 

granodiorite is coarse grained. The intrusive bodies are closely spaced 

a:nd may make up 50-75 percent of rock outcrops. Where the intrusive 

rocks cut limy shale and limestone, such minerals as garnet, diopside, 

epidote, hornblende, and related minerals were formed; in places leadzinc ore bodies occur in the contact-metamorphic zones. Some of the 

finer grained dikes are andesitic in composition and may be related to 

the volcanic activity that later gave rise to flows and pyroclastic 

rocks which cap the other rocks in the area. Silver-bearing veins cut 

these volcanic rocks and are evidently younger than the contact ore 

bodies. 

DESCRIPTION QF THE ORE DEPOSITS 

The ore deposits of the Metapan and Alotepeque districts contain 

silver, lead, zinc, copper, gold, and tungsten, but only silver, lead and 
7 4 MINERAL · DEPOSITS OF CENTRAL AMERICA 

zinc have been mined. The deposits are irregular replacement bodies-. 

and veins. 

The replacement bodies were formed in contact zones between lime--

stone and intrusive igneous rocks, especially diorite and granodiorite. 

For the most part they contain lead and zinc sulfides and a smallerquantity of copper sulfides. Pyrite, hematite, and magnetite are found 

in some deposits. The precious-metals content is generally low, and 

the deposits have been worked for their base metals. 

The veins range in width from an inch or less to 6 feet, but they 

are commonly narrow, averaging probably less than a foot, and pinch 

and swell along the strike and down the dip. They are composed of· 

quartz and sulfides, among which pyrite, sphalerite, galena, and chalcopyrite are the most common, but tetrahedrite, stibnite, pyrargyrite,. 

and polybasite also are reported. The lead, zinc, and copper minerals. 

are erratically distributed, and the veins are valuable chiefly for theirsilver content, which may be as much as 400 ounces to the ton. The· 

most productive vein in the area has been the San Pantaleon. 

META.PiN DISTRICT 

The Metapan district is in the northwestern part of El Salvador,. 

in the Departamento de Santa Ana; it lies just south of the junction of 

El Salvador, Guatemala, and Honduras. Metapan is on the El Salvador branch of the International Railways of Central America, 178. 

miles from the east terminus at Puerto Barrios and 83 miles from'. 

San Salvador. 

There has been intermittent activity in the Meta pan district since· 

colonial days, although production has been small. Iron ore was. 

mined and smelted for local consumption until about 1890. Attempts 

have been made to mine silver-bearing galena veins and copper deposits, but production in the early days was not recorded. In 1917-

a small shipment of sorted lead ore was sent from the San Juan mine 

to New Jersey. Later attempts were made to smelt the ore locally,. 

but the operation was not profitable. It is reported that ReneKeilhauer of San Salvador installed a mill at the San Juan mine in 

1950 and that production began in 1951. No details of the operation 

are available. 

SAN JUAN MINE 

The San Juan mine is at the village of San Juan, 7 miles southeast 

of Metapan on the Rio Casaquaste, at an altitude of 1,800 feet (fig. 3). 

The property covers an area of about 180 acres and is owned by Rene 

Keilhauer of San Salvador. In 1917 a shipment of 55 tons of sorted 

lead ore was made to New Jersey. This ore assayed 38.14 percent lead, 

12.76 percent zinc, and 6.65 ounces of silver to the ton. In 1931 a 

small smelter was installed on the property. The smelter worked. 

successfully, but since iron-ore flux had to be transported from El_ 
I :I 

LEAD-ZINC DEPOSITs-GUATEMALA ANDEL SALVADOR 75 

EXPLANATION 

rl 

Shaft 

IZI Head of raise or winm 

7°45' 

600 1800 Feet 

200 600Meters 

~~~--~-~ 

:FIGURE 3.-Map of the San Juan mine workings, Departamento de Santa Ana, El Salvador.· 

'Tajado, more than a mile to the southeast, and the ore was of low grade; 

the operation was not profitable. In 1951 the property was again 

·put into production, by Mr. Keilhauer, who installed a small mill and 

was producing concentrates for shipment to Mexico. 

The San Juan mine is in tactite which was formed by metamorphism· 

·of limestone along a contact with granodiorite. The tactite is composed mainly of garnet, epidote, calcite, and quartz; pockets, nodules, 

:and veinlets of pyrite, galena, and sphalerite are distributed erratically 

throughout the rock. The ore is reported to average about 4.7 precent 

lead, 2.5 percent zinc, and 1.5 ounces of silver to the ton. 
76 MINERAL DEPOSITS OF CENTRAL AMERICA 

The ore body has been explored for a length of 260 feet, a width of 

110 feet, and to a depth of 75 feet by a 75-foot shaft and 750 feet of 

underground workings. The workings are on 2 levels, four adits at 

the surface level, and the 50-foot level, connected by the main shaft 

and by a winze. 

Only the surface-level workings were accessible in 1944 because the 

lower levels were flooded. They include adits 1, 3, 4, and 5. Adit 1 

was caved in 1944. Adit 3 is in barren garnet rock from the portal to 

the crosscut to the south, but the rock from the crosscut to the face 

is mineralized. Adits 4 and 5 are both in rock that appears to be 

mineralized. · 

The workings on the 50-foot level extend to the north, south, and 

west from the shaft and nearly connect with a drift from adit 3. The 

main shaft continues 25 feet below this level and is said to be in mineralized rock at the bottom. 

SAN CASIMffiO MINE 

The San Casimiro mine is 2% miles north of San Juan, at an 

altitude of about 1,900 feet. The property has an area of about 138 

acres and is owned by Rene Keilhauer of San Salvador. No production was reported. The workings consist of a 50-foot shaft and 

several hundred feet of drifts and crosscuts which were partly caved 

at the time of visit in 1943. 

The rocks in the area are shale, sandstone, and limestone of the 

Metapan formation that strike nearly north and dip 40°-60° E. They 

have been sheared and fractured parallel to the bedding, and some 

of the shale has been metamorphosed to hornfels. 

The ore is pyrite, sphalerite, galena, chalcopyrite, and arsenopyrite, 

which replace hornfels along the bedding. The sulfides are accompanied by small quartz veins, and in places the hornfels is silicified. 

The ore is reported to contain as much as 30 ounces of silver a ton 

and 0.3 ounces of gold a ton. 

The principal workings are adit 3 and connecting workings on the 

50-foot level. This adit is in siliceous hornfels; the rock is sparsely 

mineralized at the portal, but it locally contains pockets and small 

veins of sphalerite and galena. The drift shows low-grade ore and 

some pockets of sphalerite and galena south of the adit crosscut. The 

50-foot level, flooded in 1943, is in limestone and barren hornfels for 

the most part, but the crosscut east of the shaft is in ore containing 

sphalerite and chalcopyrite. The' higher workings include 2 caved 

adits, each about 150 feet long, and several shallow pits. 

EL TAJ ADO MINE 

TheEl Tajado mine is a mile so~1;heast of San Juan, near the village of La Cerbita. The property l;>elongs to Rene Keilhauer of San 
LEAD-ZINC DEPOSITs-GUATEMALA AND EL SALVADOR 77 

Salvador. The workings con8ist of several opencuts at the summit 

of a small hill and a crosscutting adit about 20 feet below. 

The pits explore a contact zone between limestone and granodiorite. 

The limestone has in most places been silicified and metamorphosed 

to garnet rock, which locally contains specularite, magnetite, and a 

little copper stain. A block of calamine is said to have been found in 

one pit; it was presumably derived from the alternation of sphalerite. 

The adit was about 260 feet long in 1943 and was being driven in 

granodiorite to intersect the ore at depth. 

SAN ISIDRO MONTANITA PROSPECTS 

The San Isidro Montafiita deposit, about a mile northwest of Metapan, is on the Finca Santa Rosa. Shows of copper on a ridge, presumably in granodiorite, have been explored by an adit that was caved 

in 1943. Specimens on the dump contain ·quartz veins, as much as 4 

inches wide, in which there is a little chalcopyrite, galena, and pyrite. 

At San Isidro, half a mile north of San Isidro Montaiiita, a short 

adit has been driven into garnet rock locally stained with copper 

carbonates. 

EL BRUJO MINE 

The El Brujo mine is 10 miles north of Metapan, near the El Salvador-Guatemala border. Old workings, which cover an area about 

300 feet long and extend as much as 100 feet up the slope, explore a 

contact zone between limestone and granodiorite. Iron ore was 

mined from this deposit during Spanish colonial days, but the production is not known. The ore consists of magnetite and a little copper carbonate in a gangue of garnet, epidote, and calcite. 

LA ESPERANZA PROSPECT 

The La Esperanza prospect is a mile northwest of Metapan on the 

road to La Joya, on land owned by Reginalda v. de Menendez. The 

workings consist of,2 trenches and a pit 15 feet deep in limestone and 

shaly limestone striking N. 60° W. and dipping 20° SW. Nearby a 

g,ranite porphyry is exposed. Small veins and pockets of galena, 

partly altered to cerussite and anglesite, are found in the walls of the 

pit. CHAGUITE DEPOSITS 

The Chaguite copper deposits are on the farm of Felix Heredia, 

about 4* miles north of Meta pan and a quarter of a mile north of the 

village of Chaguite. Several veins of calcite, copper carbonates, and 

chalcocite, none more than an inch wide, cut andesite and red sandstone. 

At El Carmen, half a mile south of the Chaguite deposit, small 

pockets of copper carbonates in calcareous red conglomerate occur· 
MINERAL DEPOSITS OF CENTRAL AMERICA 

along fractures and are disseminated throughout the rock. The rna~ 

terial is of low grade. 

MONTE VERDE DEPOSIT 

The Monte Verde deposit is about 28 miles east of Meta pan, near· 

the Honduras border. The property was not visited, but specimens 

.show copper carbonates in a gangue of garnet, epidote, calcite, and 

quartz. Picked samples are reported to assay as high as 10 percent 

copper. 

OTHER DEPOSITS 

In the course of field work other deposits were examined. At Cafias 

Dulces, about 41/a miles northeast of Metapan, argillite and grano-

·diorite with disseminated pyrite are exposed along the banks of the 

Rio San Miguel. At San Rafael, shale containing disseminated pyrite crops out in a small stream. At Quebrada del Tigre, 1% miles 

north of Metapan, galena and pyrite occur in argillite. Fleury (1917, 

p. 435) mentions 'other shows in the district. 

ALOTEPEQUE J)JSTRICT 

The Alotepeque district in Guatemala adjoins the Metapan district 

on the north (pl. 8). It is named for the village of Alotepeque, which 

lies about 2 miles southwest of the principal mines, and covers an area 

· 6 miles long by 1% miles wide. The district can be reached by trail 

from points on the International Railroad to the west; it lies only 

about 18 miles east of the station of Agua Blanca from which roads 

passable by cars could easily be built. Concepcion, 3 airline miles 

north of Alotepeque, can be reached by car from Chiquimula during 

the dry season and is only about 5 miles from the mines by a fair trail. 

The ore deposits in the Alotepeque districts have been exploited since 

Spanish colonial times. The San Carlos, San Rafael, San Jose, and 

"San Pantale6n veins were the most productive and are said to have 

-been worked to a maximum depth of 500 feet. In 1844 the Central 

American Mining Co., an English company, acquired 17 properties 

in the district. By 184 7 this company was operating the San Carlos, 

. San Pantale6n, Santa Rosalia, Guadalupe, Atutlilico, San Jose, San 

Vincente, and Adilio mines. The production is not accurately known 

but is estimated by some to have been 20 million-40 million ounces of 

silver between 1847 and 1867, chiefly from the San Pantale6n and San 

·Carlos veins. The company ceased operations in 1867 because of lower 

grade ore and high costs of pumping water from the deeper workings. 

Local operators continued production on a small scale until 1896 but 

with only a small output. In 1911 the Guatemala Mining and Development Co., Inc., acquired the properties, and between 1912 and 1914 this 

"company drove the San Jose adit to intersect the San Pantale6n veins 

-below the deepest workings. The project was abandoned before com-

:pletion. In 1927 the claims passed to the Guatemala Mining Co. and 
LEAD~ZINC DEPOSITS-GUATEMALA ANDEL SALVADOR 79 

in 1931 were acquired by the Empresa Guatemalteca de Minas, S. A. 

This company also acquired the mine holdings of the International 

Railways of Central America. During recent years the only activities 

in the area have been small-scale operations by Jose Iten on the San 

Vincente veins. A French company, Horta Cia., denounced 14 claims 

in 1896 and did considerable exploratory work but shipped only a few 

tons of ore. In 1913 Minor C. Keith, acting for the International 

Railways of Central America, took an option on the Horta properties 

and did further exploratory work on them. A small mill was built in 

1915 at La Cafiada on the Rio de las Minas, in which about 1,500 tons 

of zinc ore, principally from Tajo de Montenegro, was treated. In 

addition, 500 tons of high-grade oxidized zinc ore was shipped from 

the El Chorro mine. 

SAN PANTALEON MINE 

The San Pantale6n mine, near Socorro in the western part of the· 

Alotepeque district, was the most productive property in the area and 

was operated by the Central American Mining Co. between 184 7 and 

1867. According to some estimates the production from this mine and 

nearby properties was 20 million-40 million ounces of silver, the bulk 

of which came from the San Pantale6n vein. The mill was at an 

altitude of 3,000 feet on the Finca San Jose about 1% miles northeast 

of the mine. ·Here the ore was dried, crushed, and roasted, then chlo-· 

ritized and amalgamated. Some high-grade ore was shipped directlyto Swansea, Wales. 

The workings explore the veins along the strike for about 3,000 feet 

and are reported to extend to a depth of 550 feet from the collar of· 

the shaft, which is 4,429 feet above sea level. Operations are said to· 

have ceased because the flow of water at the 550-foot level was SO· 

great that available pumps could not handle it. None of the workings. 

were accessible in 1944, and little information is available on the vein 

system and the ore mined. The vein system is said to consist of· 

several parallel veins striking N. 75° W. and dipping steeply southward. The ore minerals are pyrite, galena, sphalerite, stibnite, tetrahedrite, arsenopyrite, and silver sulfides; the gangue minerals are 

quartz and a little calcite. The tenor of the ore is not known, but ores. 

mined from nearby veins are reported to contain 45-1,000 ounces of· 

silver to the ton. 

The San Jose adit, driven southward in Tertiary(~) pyroclastic 

sediments and volcanic rocks to intersect the San Pantale6n veins at an 

altitude of 3,510 feet, penetrated these rocks for 2,450 feet but was. 

abandoned before the vein was reached. In 1944 the adit was open 

for about 1,700 feet. It is in Tertiary sedimentary and pyroclastic 

rocks to the caved area. It is reported that a vein was cut near the· 

present face, but its width is not known. 
80 MINERAL DEPOSITS OF CENTRAL AMERICA 

SANTA ROSALIA MINE 

The Santa Rosalia mine is northwest of the San Pantale6n mine. 

The upper workings, which yielded the ore mined, are now largely 

caved, but the workings 30 feet below are accessible. Although the 

production is not known it 1nust have been small, judging from the 

amount of work done. 

The lower adit is in interbedded tuff and shale which strike nearly 

north and dip 25 o -30° E. The vein was intersected 85 feet from the 

portal; it strikes east and dips 60°-70° S. The vein zone is from a 

few inches to 3 feet wide and consists mainly of quartz and pyrite. In 

places there is a little sphalerite. Pyrite is also disseminated throughout the altered wall rock. Assays of the vein zone show that the gold 

content is generally less than 0.04 ounce to the ton, and silver ranges 

from less than an ounce to more than 60 ounces a ton. 

PLOMOSA GRANDE MINE 

The Plomosa Grande mine is in the southwestern part of the area, 

half a mile southwest of El Socorro, at an altitude of 4,000 feet. The 

amount of ore mined is not known; it was treated in the mill of the 

Central American Mining Co. The workings include a shaft and adit, 

both of which are caved. 

Specimens found in the dumps show that the ore consisted of galena, 

sphalerite, chalcopyrite, and pyrite, in calcite and chloritized limestone 

and shale. It is reported that the vein was about 2 feet wide in the 

shaft and dipped steeply, but the strike is not known. 

TAJO DE MONTENEGRO MINE 

The Tajo de Montenegro mine is in the southeastern part of the area, 

on the headwaters of the Rio de las Minas, at an altitude of 4,925 feet 

(pl. 8). Because of landsliding which took place principally in 1938, 

1nany of the workings are caved and inaccessible. An unknown tonnage of ore was mined from these workings and was treated in the La 

Canada mill during the 1930's. 

The rocks in the area are shale, limy shale, and limestone which have 

been altered to hornfels, and an epidote-amphibole rock containing 

disseminated sphalerite, galena, chalcopyrite, and pyrite. The structure in the ore zone cannot be determined because of landsliding, but 

east of the workings the rocks strike northwestward and dip 30°-45° 

NE. At the portal of adit 6 the ore zone. is 30 feet thick, but it is of low 

grade, for the sulfides are erratically distributed throughout the rock. 

LA BALLENA MINE 

The La BaHena mine is at an altitude of 5,000 feet and is north of 

the Tajo de Montenegro mine. The workings are caved and no ore 

could be seen in place. About 100 tons of ore on the dumps show 
LEAD-ZINC DEPOSIT8-GUATEMALA AND EL SALVADOR 81 

pyrite, galena., and sphalerite, in a gangue of epidote, chlorite, and 

actinolite. None of the ore appeared to be of high grade. 

Shows of copper were seen in the stream valley east of Ballena. at 

the contact of limestone and intrusive porphyry. The ore is of low 

grade, but it could be sorted to a product containing 5-10 percent 

copper. 

SAN JOSE GRANDE MINE 

The San Jose Grande mine is on the trail from Socorro to the Rio 

de las Minas, at an altitude of 3,950 feet. Shallow surface workings 

expose silicified limestone, which is partly altered to epidote-garnet 

rock. The workings follow a fault zone which strikes N. 80° W., and 

dips 75° SW., averages 2 feet in width, and contains iron and manganese oxides. No sulfides were seen in the fault zone, but specimens 

from the workings show sphalerite, galena, and pyrite. The ore is 

disseminated throughout the rock and for the most part is low grade. 

The upper adit, above the trail, extends N. 55° E. for 50 feet; it cuts 

altered and silicified limestone that contains pockets of iron oxide. 

The lower adit trends N. 8° E. and is 96 feet long, with a crosscut to 

the east 33 feet from the portal. The limestone in this adit strikes 

N. 50° E. and dips 10~ NW. In places it contains pockets of iron oxide. 

SANTA SOFiA MINE 

The Santa Sofia mine is among the most accessible in the district, 

and the ore is well exposed in seven short adits and several shallow 

opencuts. Ore was sorted for treatment in the mill at La Canada, but 

only a small amount was milled. The workings are in limestone, in 

part metamorphosed by intrusive granodiorite ·porphyry. South of 

the workings the limestone strikes N. 55° W. and dips 70°-75° NE., 

but in the upper adits it appears to dip gently northward. 

The uppermost adits, 2, 7, and 8, appear to be in the same replaced 

limestone bed. The mineralized rock contains oxides of iron and manganese, erratically distributed. Sulfides, including sphalerite, galena, 

chalcopyrite, and pyrite, occur in pockets. The ore body is exposed to 

a depth of as much as 20 feet and averages 3 feet in thickness. Adit 1, 

the lowest, is open for a length of 90 feet. Its walls are garnet 

rock that contains disseminated galena, sphalerite, and pyrite. 

Granodiorite porphyry is exposed on the slope 40 feet south of the 

portal. 

SAN FERNANDO MINE 

The San Fernando mine is on the east side of the Rio Concepcion 

at. an altitude of 5,225-5,300 feet. An adit, 12 feet long, and several 

opencuts are the only accessible workings. A small production is 

reported. 

The deposits are veins and pockets of iron and manganese oxides 

and zinc carbonate in limestone. One vein, 4-18 inches wide, strikes 
82 MINERAL DEPOSITS OF CENTRAL AMERICA 

N. 40° W. and dips 40° NE., apparently parallel to thebedding. However, on the whole the ore is erratically distributed .throughout thezone. 

EL CHORRO MINE 

The El Chorro mine adjoins the San Fernando mine on the east, 

at an altitude of 5,200 feet. Shallow cuts and underground workings 

extend over an area 400 feet long by 250 feet wide down the slope 

that contained pockets of zinc carbonate. In 1916 and 1917 the ore 

was concentrated in log washers and calcined in furnaces nearby. The 

product was shipped to the United States. 

The ore was in pockets in limestone, which strikes N. 75° W. and 

dips 10° NE. In places there was a gossan of iron and manganese 

oxides, and the pockets of zinc carbonate occurred in this gossan and 

in the adjacent limestone. Judging from the size of the shallow pits, 

the individual pockets contained only a few tons of ore. 

SAN BARTOLO MINE 

The San Bartolo mine is north of the San Fernando mine, at an 

altitude of 4,800 feet. A series of cutsis.along the west slope of a small 

valley, where shallow ore bodies were found in limestone that strikes 

eastward and dips 20° S. The ore was in the limestone and consisted 

of pockets of lead and zinc carbonates; it is reported to have contained 

much more lead than zinc. 

OTHER MINES 

The San Carlos mine is at an altitude of 5,000 feet, near the summit 

of the Monte Cristo ridge. The workings are now completely caved,. 

but the dumps show· silicified volcanic rock impregnated with pyrite· 

and stained with iron oxides. Calcite seams cut the rock in places. 

The property was first worked by Spaniards during colonial days and· 

later by the Central American Mining Co. 

The Providencia prospect is on the San Vincente denouncement,. 

at an altitude of 4,700 feet. An adit in argillized volcanic rock showsa shear zone that strikes N. 25° E., dips 65° SE., and contains copper 

and iron-stained vein material2-6 inches wide. 

The San Jose mine is at an altitude of 4,500 feet. A vein, an 

inch to 6 inches wide, of sphalerite, pyrite, and malachite stain in a 

quartz gangue is exposed. 

The Atutilco mine adjoins the San Jose on the north. The principal 

workings are in altered volcanic rocks, which have been silicified and 

partly replaced by pyrite. The production is not known. 

The San Rafael mine is on the southwest side of a ridge, southwest 

of the La BaHena workings. The workings cover a wide area, but 

except for opencuts they were not accessible in 1944. The veins are 

in shale, sandstone, and conglomerate of the Metapan formation. In 
LEAD-ZINC DEPOSITs-GUATEMALA 83 

places these rocks are calcareous and have been metamorphosed to 

garnet rock by porphyry intrusions exposed nearby. The mine was 

productive during Spanish colonial days and at intervals since then, 

but no records of the production remain. 

GUATE)IALA 

Lead-zinc deposits are known in Guatemala in a belt that extends 

from the Mexican border eastward through the Departamento de 

Huehuetenango and the Departamento de Alta Verapaz. The principal deposits are in three areas : the Chiantla-San Sebastian district 

(pl. 9}, the San Miguel district, and the Cohan district (fig. 4). 

EXPLANATION X 

Mine or prospect 

I 

I 

>!LA CAMEL/A 

----xSUQUINAY 

10 0 10 Kilometers 

,_6:!--1--~-eo~--=s-:-:!Miles 

!FIGUR:m 4.-Index map showing locations of mines in the CohAn district, Departamento de 

Alta Verapaz, Guatemala. 

Those in the Chiantla-San Sebastian and San Miguel districts were 

being worked for lead in 1944 when the properties were visited, 

.although only on a small scale and for local use. 

The high price of lead in recent years has stimulated interest in 

the Guatemalan lead deposits, and exploratory work has been carried 

.on in the three districts. Because the Cohan district was more favorably situated than the other districts with respect to transportation, it 

was put into production first, and shipments were made in 1947. 

Preparations were underway in 1950 by an American company to 

begin production in the San Miguel district. 

TREATMENT OF THE ORE 

Treatment of lead ore in this area has followed a method brought 

from Spain by the Spanish priests of the colonial period. There has 

been no essential change in the method as it passed down from father 

to son to the present day. 

If the ore mined is high grade, it can be smelted directly; if it is 

low grade, it is first washed to remove as much limestone, clay, and 

iron oxides as possible. The washing is done in an inclined trough or 

log washer, where the fragments of limestone are picked out and· the 
84 MINERAL DEPOSITS OF CENTRAL AMERICA 

clay and iron oxides are carried off in suspension, leaving the heavier 

lead and zinc minerals as concentrates. This concentrating process is 

inefficient, and the tailings contain considerable lead, but the resulting product is well suited for the furnace. 

The Spanish furnace is a simple blast furnace consisting of a vertical chimney into whose top a mixture of ore and charcoal is charged. 

Air compressed by a column of water falling down a closed tube into 

a pressure chamber is directed into the bottom of the chimney. When 

the compressed air strikes glowing charcoal, a blast flame sufficient to 

smelt the ore is generated. The slag and molten lead run out of a small 

opening in the bottom of the chimney and are collected in a basin. 

The furnace can be operated continuously for 6 or 8 hours and can 

yield from 1,200-2,000 pounds of lead, depending upon the grade of 

the ore. The lead is generally cast into bars weighing a pound or 

two each. 

LOCAL TERMINOLOGY OF THE ORES 

Miners in the Huehuetenango area have developed a local terminology for the ores of the area. The oxidized ore is mostly porous iron 

oxides with variable amounts of lead and zinc carbonates. The ore is 

generally medium brown but varies from white or light yellow to 

nearly black. The miners have divided the ores into four general 

groups: quemaz6n, mineral de carbona-to, mineral blanco, and mineral de lava. Quemaz6n is dark brown to black, generally because of 

a high limonite content. Most of it is porous and contains relict galena 

in places. Quemaz6n is ordinarily low grade and ·may have been derived from ore with a high pyrite content. Mineral de carbonato 

is soft, porous, sandy ore, commonly yellow to light brown, th3it forms 

lenses, layers, and irregular masses in quemaz6n and limestone. It is 

high grade and generally can be smelted without washing; the source 

material was high in galena and may have contained some sphalerite 

and pyrite. Mineral blanco (lija, if hard) is white to light-yellow ore 

composed almost entirely of cerussite and anglesite. Mineral blanco 

forms in lenses and veinlets in quemaz6n and mineral de carbonato, 

and appears to be carbonate that has been carried in solution andredeposited. This ore can be smelted without concentration. Mineral 

de lava is a general name for low-grade quemaz6n or mineral de carbonato which has to be washed before smelting. 

CHIANTLA-SAN SEBASTIAN DISTRICT 

The Chiantla-San Sebastian district is in the Departamento de Huehuetenango, northwest of the village of Chiantla and on the south 

slope of the Sierra de los Cuchumatan~ ·(pl. 9). These mountains are 

a partly dissected late:-mature upland whose summits range in altitude 

from 11,000 to more than 12,000 feet above sea level; their drainage is 

for the most part radial. 
LEAD-ZINC DEPOSITs-GUATEMALA 85 

GEOLOGY 

The rocks forming the south flank of the Sierra de los Cuchumatanes 

(pl. 9) include most of the stratigraphic units known in northern 

Guatemala. Granite and gneiss of pre-Permian(~) age are exposed 

along the range front. These rocks are separated by a fault from sedimentary rocks belonging to the Santa Rosa and Chochal formations 

of Permian ( ~) and Permian age which have been cut by serpentine 

and form the south slope of the range. Near the summit, the Permian 

rocks are in thrust-fault contact with red shale and sandstone of the 

Todos Santos formation, which to the north is overlapped by limestone of Cretaceous(~) age. Pyroclastic rocks and alluvium of Pleistocene or Recent age are present in the foothills of the range. 

The granite and gneiss of pre-Permian(~) age form the low foothills just north of Huehuetenango. They are largely concealed by 

pyroclastic rocks and alluvium, but exposures in road cuts and on the 

higher slopes show that the gneiss is intimately intruded by the granite. The foliation of the gneiss is locally contorted but generally 

trends eastward and dips steeply. 

The oldest sedimentary rocks in the area belong to the Santa Rosa 

formation (see p. 15). This formation consists of a lower unit of 

interbedded sandstone, shale, and conglomerate, and an upper unit of 

red, green, gray, and black shales with interbedded shaly limestone, 

sandstone, and dolomite. The lower unit is mapped only at the foot of 

the range where beds totaling about 50 feet in thickness are exposed. 

The upper unit is well exposed on the middle slopes of the range. 

Because of complex faulting and close folding, the thickness of the 

upper unit cannot be determined accurately, but it appears to be about 

1,000 feet near the La Esperanza mine. These beds appear to be similar in lithologic composition and fauna to the Grupera formation and 

possibly part of the La V ainilla formation in Estado de Chiapas, eastern Mexico (Thompson and Miller, 1944, p. 481-504). 

In the Chiantla-San Sebastian district, limestone and dolomite beds 

of the Chochal limestone (see p. 16) overlie the upper part of the 

Santa Rosa formation and form the upper slopes of the range from 

an average altitude of 8,500 feet to the summit. A downfaulted block 

of the limestone also occurs in the foothills of the range, where the 

limestone has been cut by serpentine and is complexly faulted. Because of its resistance to weathering, the limestone crops out as prominent cliffs. The limestone is well exposed near the Finca Chochal, 

the source of its name. 

The Todos Santos formation of Jurassic and Cretaceous age, which. 

unconformably overlies the Chochal limestone, is chiefly composed of 

interbedded red sandstone, shale, and conglomerate. For the most 

part these rocks have not been metamorphosed, but near faults the 
86 MINERAL DEPOSITS OF CENTRAL AMERICA 

shale locally has a slaty cleavage. The pebbles making up the conglomerate include quartzite, granite, sandstone, limestone, dolomite, 

schist, and gneiss, all probably derived from the underlying Permian 

and older formations. 

The limestone unit resting upon the Todos Santos formation north 

of Chochal is light gray, dense, fine grained at the base, for the most 

part thick bedded or massive, and weathers in rough, craggy outcrops. 

It contains many sinkholes, and in places a karst topography has been 

developed. This limestone is lithologically similar to the Upper 

Cretaceous limestone (seep. 23), with which it is therefore tentatively 

correlated. 

The granite and gneiss that form the belt between Huehuetenango 

and Chiantla are not in contact with the Permian strata except where 

they are brought together by faulting, and their relative age is therefore not certainly known. Since pebbles and boulders of granite, 

gneiss, and schist are found in the lower beds of the Santa Rosa formation, the granite and the metamorphic rocks are probably for the most 

part pre-Permian. However, near San Miguel Acatan granitic rocks 

cut Santa Rosa strata and are therefore younger, and Termer (1932, 

p. 246) found diorite dikes that cut Permian slates near El Quetzal, 

Huehuetenango. At least two periods of intrusion must be represented in the Sierra de los Cuchumatanes, and there may well be 

others not yet recognized. 

Serpentine forms a wide zone along the foothills of the southern 

flank of the mountains. On the south the serpentine is in fault contact with the granitic rocks, but elsewhere it is intrusive into the Santa 

Rosa and Chochal formations. Generally the intrusive contacts are 

concordant with the structure in these rocks, but in places they are 

discordant. Magnesite veins and pods occur locally in the serpentine 

and are for the most part small and irregular. Generally the serpentine is altered, sheared, and foliated; it weathers to a thin poor soil 

that supports only sparse vegetation. 

Three principal sets of faults have been mapped in the area. The 

faults of the major set trend westward, dip steeply southward, and are 

reverse faults. The faults at Las Manzanas and the Finca Chochal 

belong to this set. Another set, which includes the La Sara and La 

Esperanza faults, consists of normal faults that trend westward. The 

third set consists of normal faults that trend northwestward and cut 

across the general strike. A few other minor faults of small displacement also trend northwestward and northward. The westwardtrending reverse and normal faults have the greatest displacement. 

Some of these faults are mineralized and may have been the channels 

for ore-bearing solutions. 
LEAD-ZINC DEPOSITs-GUATEMALA 87 

DESCRIPTION OF THE ORE DEPOSITS 

The lead-zinc ore bodies of the Chiantla district are replacement deposits in limestone of Permian age. They may be divided into two 

types : those that extend along faults, and those that follow. the bedding. The two are generally found together, and the fault zones may 

have been the channelways for the solutions that formed both kinds 

of ore bodies. 

The primary minerals of the ore bodies are galena, sphalerite, and 

pyrite. These minerals have been oxidized-the galena to anglesite 

and cerussite, the sphalerite to smithsonite and calamine, and the 

pyrite to iron oxides. The oxidized ore is generally a boxwork of 

porous light-brown limonite containing variable amounts of lead and 

zinc minerals. Galena is the only sulfide found in the oxidized ore ; 

it occurs as small kernels surrounded by anglesite and cerussite, its 

oxidation products. 

The ore bodies that follow faults are lenticular and discontinuous 

along the strike. Figure 5 shows one of these ore bodies at the La 

Esperanza mine; it was mined from an open pit that was 80 feet long, 

as much as 35 feet wide, and more than 25 feet deep in· 1943. The 

shallow pits and the shaft near the main pit explore a mineralized 

bed extending out from the fault. This bed has been mined for about 

300 feet west ~f the fault (fig. 5) and more than 100 feet down the 

dip. The Tor16n ore bodies (pl. 10) appear to be a combination of the 

two types defined above, having resulted from irregular replacement 

along bedding adjacent to a fault zone. The ore zone is 1,400 feet 

long, as much as 350 feet wide, and has been mined to a depth of 120 

feet. Mineralization is not continuous; the ore appears to be in several 

.shoots, some of them as much as 200 feet long and 30 feet wide. 

Except for a few relict kernels of galena, oxidation is complete 

in the workings visited. The only primary ore seen-fine-grained 

sphalerite, pyrite, and galena-can1e from the Santa Rosa workings 

of the Tor16n mine, about 100 feet below the surface. This probably 

represents the minimum depth of the oxidized zone, for elsewhere at 

this depth the ore i.s cmnmonly oxidized. 

As the miners have sought only lead ore, the ground rich il~ zinc 

has not been explored. Although some zinc minerals are found in the 

oxidized zone, the bulk of the zinc was probably leached and transported downward; part of it may have been precipitated as smithsonite and calamine in the lower levels and on the borders of the ore 

bodies and the remainder carried out in ground water. 

TORLON MINE 

The Torl6n mine (pis. 9, 10) is 15 miles northwest of Chiantla, in 

the foothills of Sierra de los Cuchumatanes. The workings are at 

388364-57-7 
88 MINERAL DEPOSITS OF CENTRAL AMERICA 

altitudes of 6,600-7,300 feet (pl. 10). The property, owned by the 

Recinos family of. Huehuetenango, has been productive for more 

than 200 years. The ore is mined, washed, and smelted by primitive 

methods, and the pig lead is sold in. Guatemala. The rate of p:roduction in 1944 was about 5 tons of lead a month. 

The lowest opening at the Tor16n mine is adit :1, which is entirely 

in serpentine; it was driven for about 300 feet but is caved from the 

200-foot mark to the face. A raise extending 75 feet up from the face 

is reported to have cut ore. 

W orkjngs 2, at an altitude of 6,840 feet, are in serpentine and lime~ 

stone on the hanging wall of the Tor16n fault. Two adits, one extend--

ing westward and the other northwestward from the portal, explore 

flat or gently dipping ore bodies in fractured and breccia_ted lim~ton~~ 

.. A .. t the portalthe south adit is in rubble, and for 60-80 fe.et from th~ 

portal it is in sheared serpentine, which is in fault contact with lime ... 

stone that extends to the face. Little ore was seen in 1943 on the drift 

level, but -a raise 90 -feet from the portal shows ore. Another raise 15 

feet to the west connects with the stope above. In· this stope the -ore· 

occurs in pockets in limestone. A sample (T14) collected on the south 

side of the stope gave the following assay: 9.1 percent lead, 18.7 percent zinc, and 1.3 ounces of silver to the ton. The high zinc content 

may indicate that this ore was transported by oxidizing solutions and 

precipitated here. 

The north adit is in rubble, pyritic clay, and limestone breccia. 

Irregular ore bodies were mined in the limestone breccia beginning 

about 140 feet from the portal ; a section 60 by 70 feet was partly 

stoped in a vertical range of about 20 feet. Sample T13 was collected 

in the south end of the stope (see table). 

The San Juan workings explore an irregular ore body in limestone. 

Two adits connect with the workings, one at an altitude of 6,933 feet 

and the other at an altitude of 6,953 feet. The workings are extremely 

irregular, and as they follow the richer zones they give little idea of 

the ore body as a whole. The ore appears to replace limestone along 

fractures and faults extending northwestward. Two principal stopes, 

the La Iglesia and the San Juan, are accessible. Other ore bodies·, 

were mined to the northwest, but in 1943 the workings were caved 

and inaccessible. Irregular stopes extend out from the drifts and the 

crosscuts in the mine. In places the stoping extended nearly to the 

surface, which is at an altitude of 7,000 feet in the western part of the 

mine area. Assays of nine samples collected in the workings are listed 

below. These san1ples indicate the grade of ore to be expected in the 
LEAD-ZINC DEPOSITS-GUATEMALA 89 

walls of the stopes and workings sampled. However, the tnin~rs have 

a voided lower grade material and as far as possible the, working~ 

were kept in ore. 

Assays of lead-zinc ore from the Torl6n mine, Guatemala 

[Birger Sundstri5m, Mexico City, Mexico, analyst] · 

Sample no. 

T2 ______________________________ _ T3 ______________________________ _ T4 ______________________________ _ T7 ______________________________ _ T9 ______________________________ _ TIO _____________________________ _ 

Tl4 T13---------------------------~-- _____________________________ _ Tl5 _____________________________ _ 

Pb (percent) 

7. 1 

10. 3 

8. 8 

4. 7 

17. 3 

10. 7 

12.3 

9. 1 

17.4. 

Zn (percent) 

·10. 0 

7. 3 

9. 2 

36.0 

13. 3 

14.9 

2. 9 

18.7 

1. 8 

Ag (oz per ton) ' 

1. 3 

. 8 

1. 4 

2. 3 

. 27 

1.3 6 . 

The portal of Galeria Nueva (also called the La Canada adit),:no;rth 

of the San Juan workings, is in serpentine. The adit trends westward 

and at 135 feet from the portal crosses the Torl6n fault, whjch here 

dips westward. Iron-stained limestone forms the hanging wall, but 

the adit rises after passing through about 20 feet of limestone and 

enters limestone rubble probably related to faulting and slumping of 

leached limestone. 

The Los Ramos workings, west of the Galeria Nue'Va, ·eX:piore ·aJl. 

ore body along a northward-trending fault zone which dips 65°-~0° E. 

An ore body has been mined along the fault, and pockets of ore extend 

irregularly out into the adjacent limestone and also follow parallel 

fractures. Stoping has been carried on over a length of 165 feet, a 

width as great as 35 feet, and to a depth of about 60 feet at the south 

end of the workings. Samples T9 and T10 were collected at the south 

end. 

The adit F workings to the west incline downward to the northwest 

and then curve back eastward; they explore ground that is probably 

in the upper part of the Los Ramos fault area. 

Adit 3 explores ore bodies that extend along steep fractures and also 

along the bedding adjacent to the fractures. The principal faults 

trend.northward to northwestward and most dip steeply eastward, 

although some dip steeply westward. The ore bodies that have been 

mined irregularly replaced the fractured limestone in and adjacent to 

the fault zones. As shown by the stoping, the mineralized zone has 

been explored for 160 feet along the strike and as much as SO feet in 

width. The deepest workings were 35 feet below the adit level in 1943. 
90 MINERAL DEPOSITS OF CENTRAL AMERICA 

The Verde adit is entirely in serpentine except for a crosscut to the 

south that passes below adit 3. Near the face of the crosscut the serpentine is in fault contact with the limestone. The contact dips 60° S. 

The face is caved, but ore is said to have been found a short distance 

beyond. 

Adit 4, which is in limestone, was driven 295 feet westward but is 

caved 75 feet from the portal. Ore is said to have been cut in the adit 

135 feet from the portal, more or less on strike with the projection of 

the Los Ramos fault, and to continue westward nearly to the face and 

northwestward along the crosscut. 

Adit H, 80 feet west of the adit 4 portal, is in limestone rubble, 

but adit A, 60 feet farther west, exposes ore of fair grade in limestone, 

with galena veins and pockets at the face. Adit B, 50 feet north of 

adit A, is in altered limestone containing veinlets of galena and carbonate ore. A sample of this material assayed 13.6 percent lead and 25.2 

percent zinc. 

Adit N, at an altitude of 7,154 feet, shows porous oxide and carbonate ore locally containing concretionary iron oxides; sample T7 is 

from the northern part of the workings. The high zinc content is 

notable. Adit M contains massive carbonate ore which locally also has 

a high zinc content. 

Exploratory work at the Torl6n :mine has thus far been to only a 

shallow depth, and stoping has been confined almost entirely to soft 

oxidized ore. According to available information, the main ore shoots 

are parallel to the Torl6n fault. 

CHOCHAL PROSPECT 

The Chochal prospect is about 2 miles ·northwest of the ,Finca 

Chochal, at an altitude of 10,000 feet (pl. 9). Two short adits and 

several shallow pits explore ore that replaces limestone along the bedding. The property has been worked intermittently, and some on 

from the workings has been treated in the furnace at the Tziminas mine 

and in a furnace built at the Finca Chochal. Because the ore; contains 

a little lead and much zinc, the test runs were not satisfactory. 

The adits show ore which replaces limestone and dolomite alang 

wavy bedding surfaces. The ore consists chiefly of compact zinc and 

lead carbonates, but some relict galena can be found. Iron oxiqes are 

present in places, but on the whole they are less abundant than in 

nearby ore deposits. 

The ore body in adit 1 had been explored for about 100 feet along 

the strike and about 40 feet down the dip in 1943. It ranges in thickness from 6 to 48 inches and becomes narrower down the dip but is 

locally irregular. In adit 2 the ore is irregularly distributed through-
LEAD-ZINC DEPOSITs-GUATEMALA 91 

out fractured limestone. The assays listed below were made of ore 

samples, collected from adit 1. 

Assays of lead-zinc ore from the Chochal mine, Guatemala 

[Birger Sundstr5m, Mexico City, Mexico, analyst] 

Sample no. Pb (percent) Zn (percent) Ag (oz per ton) 

Ch1------------------------------ Ch2------------------------------ Ch3------------------------------

14.3 

15.5 

3. 6 

MINERAL DE OCRE MINE 

24.2 

23. 1 

30.4 

1.80 

------------ .. 87 

The Mineral de Ocre mine is at an altitude of 10,350 feet and abbut 

500 feet west of the Chochal prospect (pl. 9) . The workings consist of 

several pits, now caved, in the Chochallimestone. The property was 

last. operated in 1938, when the ore was treated in the furnace at the 

Tziminas mine. 

The mineralized zone trends N. 70° W., is about 40 feet wide, and 

has been explored for about 200 feet along the strike. The ore is 

composed of iron oxides and lead and zinc carbonates in veins and 

irregular pockets in the limestone and dolomite. 

TZIMINAS MINE 

The Tziminas mine is about 800 feet west of the Mineral de Ocre 

mine, at an altitude of about 10,000 feet (pl. 9). The workings 

include many shallow pits and an adit in gossan which crops out 

prominantly. At one time ore from this and nearby properties was 

smelted in a small furnace on a stream nearby. The production is not 

known, but judging from the size of the slag pile only a few tons of 

ore was treated. The volume of water available is small except during 

the rainy season. 

The gossan averages 60 feet in width and extends along the strike for 

about 400 feet. Many shallow pits show that the lead and zinc carbonates making up the ore occur in veins and pockets throughout the 

gossan and in the adjacent limestone and dolomite. Ari adit nearly 

200 feet long was driven by the American Metals Co. into the gossan, 

but the ore found was mostly low grade, indicating that the original 

sulfide was largely pyrite. · 

Notwithstanding the low grade of the material exposed in the workings, further exploratory work :m.ay be warranted in the .ChochalTziminas-Mineral de Ocre area. The deposits are all in the same fault 

zone, and ore bodies may be present at depth and in areas that have 

not yet been explored. 
92 MINERAL DEPOSITS OF CENTRAL AMERICA 

LA SARA MINE 

The La Sara mine is on the boundary between the municipalities of 

San Sebastian and Todos Santos, at an altitude of 10,625 feet, on the 

peak west of Chochal (pl. 9}. Ore from the La Sara workings was 

treated in the Tziminas furnace during the 1920's, but the mine was not 

active in 1944. 

A 220-foot long pit with an average width of 20 feet and a depth of 

20-30 feet trends N. 55° W. and follows a shear zone nearly parallel 

to the bedding in limestone, which dips 70° SW. 

The ore consists mainly of banded lead and zinc carbonates mixed 

with iron oxides and contains relict crystals of galena. Pyrite was 

noted in some specimens on the dump, and thin crusts of malachite on 

. carbonate ore are found in a few places. The workings in 1943 were 

partly filled with waste rock, and the ore was covered in most places. 

LA ESPERANZA MINE 

The La Esperanza mine (fig. 5} is on the ridge above Las Lavaderas, 

about 2% miles east of the Finca Chochal (pl. 9; fig. 5) ; the workings 

are at the base of a limestone cliff, about 9,700 feet above sea level. 

The mine has been in operation since Spanish colonial days, and since 

1914 has been controlled by Benjamin West and his family. Production was high during the period when ore was being mined from the 

opencut, but since then the mine has been worked only intermittently. 

Mr. West installed a mechanized treatment plant about 1920, but it 

was not successful. Since then ore has been intermittently treated 

in a furnace ( chimbo) and oven ( horno ocote) constructed in the 

valley below the mine. 

The ore at the La Esperanza is for the most part porous lead and zinc 

carbonates formed by the oxidation of galena and sphalerite. The 

oxidation is nearly complete, although relict galena is found locally. 

Iron staining is not pronounced in most places. Solution of the adjacent limestone accompanied the formation and alteration of the ore, 

and considerable slumping has occurred, as a result of which the ore 

layer is wavy and irregularly banded. 

One of the ore bodies, which has been mined in an open pit, followed 

a steep fault striking N. 40° E. The ore has been mined for a length 

of 120 feet, a width of as much as 40 feet, and a depth of 60 feet. 

Pockets of carbonate ore were mined from partly replaced and fractured limestone and dolomite on both sides of the pit. 

Ore occurs also along the bedding and in fractures parallel to the 

bedding, striking northwestward along the base of the cliff west of the 

pit. Several irregular workings follow the ore zone for a distance 

of 400 feet or more, as shown in figure 5. Because of leaching and 

slumping, the exact nature of ore deposition could not be learned, but 
~rousearbon.~teot"C! 

Approximate contact 

IZI Headofl'lise.orwinze 

---=:L. Fault,show~na:dip; dashed where approximately located 

EXPLANATION 

~ Faultzone,showln&dip 

,...__ Strikeanddipofbeds 

~ ::::{::: ............. lnelinedworldnp; Clvtdworkinp Opencut eheYrons point down win~ut ··•1\',\dlll/i, 

Dump 

~ 

Shoft 

E4 

Sample 

>- Ad it 

Fracturedhmestone 

till Footofr11seorwinze 

9643' 

Altitudeofworkings,infeet 

, 0 20Mtters 

25 0 75 FNt 

Contourlm.rv.ISfeet 

b.tum is approximate se.t Jew/ 

' % ~ ~ " ~ ~ 

I!' < 

FIGURE 5.-Map of the La Esperariza mine workings, Departamento de Huehuetenango, Guatemala. 

1.::"1 

t;<j 

> 

1:::1 I 

ts 

z 

c 

1:::1 

tz:j 

1-t;j 

0 

Ul 

1-1 

8 

I 

~ 8 

tz:j 

~ 

e.o 

Cl.:l 
94 MINERAL DEPOSITS OF CENTRAL AMERICA 

generally the ore appears to replace a layer of massive lhnestone 

interbedded with shaly limestone. 

Assays of the ore show wide variation in the lead and zinc content 

(see table below). Samples E1 through E6 were collected in the 

underground workings at localites indicated on the map, and sample 

E7 was taken from the dump. 

Assays of lead-zinc ore from the La Esperanza mine, Guatemala 

[Birger Sundstrom, Mexico City, Mexico, analyst] 

Sample no. Pb (percent) Zn (percent) Ag (oz per ton) 

E1 ______________________________ _ E2 ______________________________ _ E3 ______________________________ _ E4 ______________________________ _ E5 ______________________________ _ 

E6 ______________________________ _ E7 ______________________________ _ 

17.9 

28.6 

11. 5 

5. 9 

19.3 

1.4 

1.2 

1.3 

1. 0 

1. 9 

20. 7 

1.5 

33.6 

14.3 

3. 51 

2. 74 

4. 55 

. 39 

The miners are fairly skilled in selecting good lead ore and have 

followed the high-grade shoots as far as possible. Abandoned workings are backfilled with waste and low-grade material. 

OTHER MINES 

The Almengor mine, about 2 miles southeast of the La Esperanza 

mine, was productive during colonial days, but the workings are now 

caved and were inaccessible in 1943. 

The Buena Vista mine,. about 4 miles southwest of the Finca Chochal, is also credited with a small production. The workings were 

inaccessible in 1943. SAN MIGUEL DISTRICT 

The San Miguel district is about 30 miles north-northwest of Huehuetenango, near San Miguel Acatan, a village on the Rio Santa Catarina. The district could most easily be reached in 1944 by driving 

northward from Huehuetenango to Tojquiaj, a distance of 261h miles, 

and thence 5 miles on horseback over steep trails westward to the Villa 

Linda mine. Because of the high altitude of Tojquiaj, which is 11,500 

feet above sea level, lead from the district was formerly transported 

by pack animals over a lower route to the west through the villages of 

Concepcion and Todos Santos to Huehm~tenango where it was transshipped by truck to Guatemala City. 

In 1948 it was reported that C. F. and F. M. Corzelius and W. J. Hill 

organized the Compaiiia Minera de Huehuetenango and acquired the 

Villa Linda and Rosario mines. Work was begun in 1949 on a truck 

road from Tojquia,j to the mines and was said to be near completion in 

1951. A mill is planned at Villa Linda for concentrating ore from 

the two mines. The concentrates will be shipped by truck to San 
LEAD-ZINC DEPOSITs-GUATEMALA 95 

Felipe, a station on the railroad near Quetzaltenango, then by train 

to the smelter at Torreon, Mexico. · 

Considering the size and grade of the ore bodies found in the Rosario 

and Villa Linda mines, the San Miguel district may develop into 

an important lead and zinc producer when transportation facilities 

are improved. Despite the long distance from shipping points, the 

district warrants further exploration. 

GEOLOGY 

In the San Miguel district the lead -zinc deposits are in the Ixcoy 

formation, 500-1,500 feet above its base. In this area the lower part 

of the Ixcoy formation includes interbedded dolomite . and massive 

limestone, which for the most part are poorly bedded. Members consisting chiefly of dolomitic breccia and conglomerate are common and 

in places are 50 feet or more thick. Karst topography has been developed in some areas, and sinkholes as much as 300 feet in diameter 

have been formed. The Ixcoy formation rests on shale, sandstone, and 

marl of the Todos Santos formation, a quarter of a mile west of the 

Rosario mine; the contact dips gently westward and appears to be an 

angular unconformity. Between San Miguel and Villa Linda the 

Todos Santos formation is again exposed where it has· been brought 

to the surface in an anticline. The basal limestone beds of the Ixcoy 

here overlie the Todos Santos formation, which has been truncated 

by erosion, with an angular unconformity of about 15°. The uplift 

and erosion clearly occurred in the interval between the deposition of 

the Todos Santos strata and the overlying Ixcoy formation. 

The structure of the central part of the Sierra de los Cuchumatanes 

is not well known. The older rocks that make up the west flank 

include shale and sandstone which are probably part of the Santa 

Rosa formation, and they have been intruded by granite and serpentine. The overlying Todos Santos formation and limestone of the 

Ixcoy formation rest unconformably on these rocks and dip westward 

at low angles. The Todos Santos beds are exposed from San Miguel 

Acabin to a point 5 miles to the east, where they are overlapped by 

limestone of the Ixcoy formation. In this area the dip appears to 

be gently eastward, and gentle dips predominate to the crest of the 

range. Near Tojquhij and Chemal at the crest of the range, beds correlated by Sapper (1937, p. 31) with the Sepur formation of Eocene 

age have been preserved from erosion by downfaulting. Between 

Chemal and the west slope of the range the Cretaceous rocks have 

locally been sharply folded along northwestward-trending axes. 

DESCRIPTION OF THE ORE DEPOSITS 

The lead -zinc deposits in the district are replacement bodies along 

faults and along the bedding in the limestone and dolomite of the 

Ixcoy formation. As exploratory work had reached a relatively 
96 MINERAL DEPOSITS OF CENTRAL AMERICA 

shallow depth in 1944, the downward extent of the ore bodies was not 

known, but several have widespread outcrops. The ore from the sur~ 

face downward to depths of 75 feet or more is almost entirely oxidized 

except for relict galena. Below 75 feet sulfides are found, including 

pyrite, sphalerite, and galena. 

ROSARIO MINE 

The Rosario mine is at an altitude of 6,300 feet on the Rio Coya, 

about 31;2 miles southwest of San Miguel (pl. 11). The deposit was 

discovered about 1917 by Cipriano Gonzalez, who later sold the mine 

to Santiago Molina, by whom it was sold in 1924 to the American 

Metals Co. of New York. Between 1925 and 1927 this company 

explored the property, but its plans for exploitation were not carried through because of high transportation costs. About 193o' the 

mine was leased to Virgilio Recinos of Huehuetenango, who erected 

a small furnace on the property. Production was reported to be 8-12 

tons of lead a: month in 1944, and the total production for an 18-year 

period is estimated to be about 2,000 tons. 

The Rosario mine is in the Ixcoy formation, which is well exposed 

in the mine area. This formation consists chiefly of massive limestone 

and dolomite but includes layers of conglomerate and breccia. North 

of the mine the limestone strikes westward and dips gently northward. 

Faults in these rocks trend northward, westward, and northwestward. 

The magnitude of the displacements is not known, but on some of the 

faults striking westward it may be several hundred feet. A third 

of a mile west of the mine the underlying shales of the Todos Santos 

are exposed. 

The limestone and dolomite have been partially replaced by lead and 

zinc sulfides, now largely altered to lead and zinc carbonates. Assays 

of the ore show that on the whole the zinc content is low; its principal 

constituents are cerussite and iron oxides. Samples collected· in the 

workings in 1944 assayed as shown in the table below. 

Assays of lead-zinc ore from the Rosario mine, Guatemala 

[Birger Sundstrom, Mexico City, Mexico, analyst] 

Sample no. Pb (percent) Zn (percent) Ag (oz per ton) 

Et1 ______________________________ _ JR2 ______________________________ _ Et3 ______________________________ _ Et4 ______________________________ _ Et5 ______________________________ _ Et6 ______________________________ _ Et7 ______________________________ _ Et8 ______________________________ _ JR9 ______________________________ _ 

1. 9 

3. 7 

10.6 

42.9 

19.8 

30. 8 

2. 7 

23.3 

24.8 

3.5 

2. 6 

3.9 

1.8 

2. 9 

2.7 

5. 1 

2.2 

2.3 

0. 10 

. 97 

2.03 

3.51 

6. 42 

3. 52 
LEAD-ZINC DEPOSITS-GUATEMALA 97 

Two principal ore bodies have. been explored in the workings; The 

eastern ore body follows a fracture zone striking N. 15° W. and dipping 80° SW. Ore ... has been stoped 25 feet above the 6,132-foot level 

along the fracture zone and out along extensions of the ore body parallel to the bedding. The western ore body below the opencut has be~n 

explored downward to an altitude of 6,214 feet. The central part 

of this ore body shows high-grade ore over a width of 40-60 feet and 

a length of as much as 100 feet, with projections northwestward 70 

feet and northeastward along fractures for 120 feet. The northwestward projection seems clearly to follow fracture zones, but the 

northeastward projection may follow bedding as well as fractures~ 

In a winze sunk 33 feet below the lowest level in the western part of 

the mine, sphalerite, galena, and pyrite that replace limestone are 

found. Assays of this ore are reported to show 18-20 percent lead 

and as much as 37 percent zinc. 

Both ore bodies should be explored further; it seems likely that the 

Rosario property will develop into an important producer of lead and 

zinc. However, with the exception of pockets of carbonate ore, the 

ore below 6,200 feet in altitude will probably be largely sulfides, and 

the zinc content will be higher than in the carbonate ore. In deeper 

exploration, account should be taken of the fact that the base of the 

Ixcoy formation may lie about 500 feet below the surface. The ore 

may not end downward against this contact but may break up into 

fissure or lode veins below, although where marly beds are present 

in the Todos Santos formation, replacement bodies may be formed. 

BOLA DE ORO MINE 

The Bola de Oro mine property, which adjoins the Rosario mine on 

the east (pl. 11), is owned by Virgilio Recinos of Huehuetenango. Ore 

mined here has been treated in the Rosario furnace. The production 

has been small, probably less than 100 tons of lead. The property 

was idle when visited in 1944. 

The workings are in the Ixcoy formation. Underground the rock 

is a sandy and clayey breccia enclosing residual fragments of limestone. The workings slope downward to the north and probably 

follow a northward-dipping bed that strikes N. 70°-80° E. The stope 

width ranges from about 20 feet near the surface to 60 feet in the 

lower workings, although the ore is only 2-6 feet thick. A sample 

from a pillar in the western part of the mine assayed 17.1 percent 

lead, 5.1 percent zinc, and 1.9 ounces of silver per ton. On the whole 

the ore appears to be erratically distributed. 

VILLA LINDA MINE 

The Villa Linda mine (pl. 12) is 31h miles east of San Miguel, on a 

tributary of the Rio Santa Catarina. The property includes the Villa 
98 MINERAL, DEPOSITS OF CENTRAL AUERICA 

Linda, Felicidad, and Argentina denouncements, with a total area of 

about 200 acres. The Villa Linda denouncement contains the San 

Juan, San Miguel, and Rosario workings, all at an altitude of about 

8,600 feet. Shows of lead ore were discovered' in 1912 by Miguel 

Gomez, who sold the property soon afterward to Lucas Escobedo, 

Federico Calderon Herrera, and Federico Calderon Perez, who operated it until 1915 and then sold it to Aurelio, Marcos, and Teodoro 

Recinos, who worked the mine intermittently until1925. In 1925 and 

1926 the American Metals Co. optioned the property and completed 

about 175 feet of adit and shaft. Since 1926 the property has been 

operated continuously on a small scale by the Recinos family. The 

lead production of the mine in short tons, as estimated by Humberto 

Recinos, the mine manager, is 1912-15, 900 tons; 1915-20, 38 tons; 

1920-44, 2,880 tons. The lead is transported by pack trains to Huehuetenango and thence by truck to Guatemala City. 

The Villa Linda mine is in the Ixcoy formation, which in this area 

appears to dip gently, although the bedding is obscure in most places. 

The formation is chiefly limestone conglomerate and breccia with interbedded layers of massive limestone. The fragments of conglomerate and breccia range in diameter from a fraction of an inch to more 

than 2 feet. These rocks have been cut by eastward-trending faults 

and fractures which appear to control the ore in the San Miguel workings. The Rosario and San Juan ore bodies appear to follow the 

bedding. ·: 

The San Miguel workings are shallow excavations that follow 

faults and fractures striking eastward and dipping steeply southward. 

They are reported to have yielded much high-grade carbonate ore 

shortly after the Villa Linda deposit was discovered. Ore is still 

available in the workings, but none is being stoped because of difficult access to the lower stopes. A sample collected in a short adit 

assayed 18.9 percent lead, 3.5 percent zinc, and 3.7 ounces of silver per 

ton. 

The Rosario workings are west of those of the San Miguel and explore an ore body developed by inclined workings and a level 26 feet 

below the portal. The ore body appears to follow the bedding, which 

dips 45 ° SW; it has been stoped for a length of 60 feet. A sample 

from the walls of the lower level contained 19.4 percent lead, 3.3 percent zinc, and 4.9 ounces of silver a ton. 

The San Juan workings (pl. 12), which are east of those of the San 

Miguel, explore an ore body striking northwestward, probably parallel to the strike of the enclosing limestone. The part of the ore body 

explored up to 1944 was 135 feet long, had a maximum width of 85 

feet, and had a thickness of about 48 feet. The ore consists for the 

most part of porous carbonates ( quemazon and mineral de carbona to) 
LEAD-ZINC DEPOSITS-GUATEMALA 99 

and is rather uniformly distributed throughout the workings. Except for the presence of limestone and dolomite at the portal and on 

the northeast side, the workings are in carbonate ore. Whether the 

work of the American Metals Co. outlined the boundaries of the ore 

is not known, for the upper portals were caved in 1944 and the workings could not be examined. The ore in the San Juan ore body is all 

of good grade, and some of it is of high grade (see table below). 

Assays of lead-zinc ore from the Villa Linda mine, Guatemala 

[Birger Sundstrom, Mexico City, Mexico, analyst] 

Sample no. Pb (percent) Zn (percent) Ag (oz per ton) 

VL1 _____________________________ _ 30. 8 5. 3 2.68 VL2 _____________________________ _ 29. 0 3. 6 VL3 _____________________________ _ ------------ VL4 40. 8 2. 4 4. 55 _____________________________ _ 37.4 2.3 VL5 _____________________________ _ ------------ 31. 5 4. 1 3. 21 VL6 _____________________________ _ 27. 7 2. 9 VL7 _____________________________ _ ------------ 25.0 2. 7 1. 93 VL8 _____________________________ _ 24.7 2. 1 VL9 _____________________________ _ ------------ 49.6 1.4 3.80 VLlO ____________________________ _ 18.9 .3. 5 3. 68 VL11 ____________________________ _ 19.4 3. 3 4. 85 VL12 ____________________________ _ 25. 9 2. 9 3. 22 VL13 ____________________________ _ 39.9 2.8 3. 90 VL15 ______________________ -... - ___ _ 19. 1 ------------ ------------

Other workings in the Villa Linda mine are on the Felicidad and 

Argentina denouncements. The Felicidad workings are about 1,000 

feet east of the San Juan workings, at an altitude of 9,100 feet. An 

incline 15 feet deep and as n1uch as 7 feet wide is reported to have 

yielded ore from which 304 pounds of lead was smelted. The ore zone 

now exposed in the workings is a vein 6 inches to a foot wide containing iron oxides and carbonate ore. The vein strikes N. 70° E. and dips 

ooo NVV. 

The Argentina workings are about 1,200 feet west of the Rosario 

workings at an altitude of 8,500 feet. The rock exposed in shallow 

cuts is crushed limestone with narrow seams and small pockets of 

galena and cerussite. 

OTHER DEPOSITS 

The Candelaria prospect, about 2 miles east of the Rosario mine, is 

reported to be promising. Other deposits are said to lie west of the 

Rosario mine. 

COBAN DISTRICT 

The Cohan district, in the Departamento de Alta Vera paz, contains 

shows of lead and zinc distributed over a wide area (fig. 4). Several 

deposits in the district have been explored, and two of them, the San 

Joaquin and Caquipec mines, have produced ore. 
100 MINERAL DEPOSITS OF CENTRAL AMERICA 

Transportation of ore from the mines to shipping points does not 

offer the same difficulties in the Cohan district as in the Huehuetenango area. A road passable by truck the year round goes from 

Cohan to Pancajche, whence freight can be transported by the Vera paz 

Railway 291;2 miles to Panz6s and then by barge 110 miles by way of 

Lago de Izabal to the port of Livingston. Exploration was being carried on in 1948 at several places in the Cohan area by the Compafiia 

~finera de Guatemala, a company financed in the United States. 

GEOLOGY 

The rocks in the Cohan area include gneiss and schist of pre-Permian 

age, which are overlain by Permian shale, sandstone, conglomerate, 

limestone, and dolomite. All these rocks have been intruded by granitic rocks and serpentine. Younger sedimentary rocks of Cretaceous 

age overlap the older rocks on the north. The gneiss and schist are 

part of the belt of basement rocks extending eastward through Guatenlala along the valleys of the Rio Salegua, Rio Negro, and Rio 

Polochic. In the Cohan area these rocks are exposed north of Tucuru, 

where they have been brought to the surface by faults. 

Shale, sandstone, and conglomerate of the Santa Rosa formation 

are exposed in many places in the valleys of the area south of Co ban. 

The formation is lithologically similar to the Santa Rosa of the :ij:uehuetenango area but contains a greater· proportion of coarse sandstone and conglomerate. However, the upper beds are more shaly, 

and intercalated limestone be~s containing fossils grade upward into 

limestone correlative with the Chochallimestone. 

This limestone, together with some interbedded dolomite, caps the 

main ranges in the southern part of the Departamento de Alta 

Verapaz. These rocks form bold cliffs which are somewhat higher on 

the south side of the range than on the north side, and everywhere 

they form rugged terrain. Much of the limestone and dolomite is 

massive, but in places the members are medium to thin bedded. In 

the Cohan area these rocks are the hosts of part of the lead-zinc ore 

bodies. 

On the north the Chochal limestone is in fault contact with 

the Cohan formation, of Cretaceous age. The Cohan is probably 

equivalent to the Ixcoy, for they both contain Early Cretaceous fossils 

and consist of interbedded massive limestone and dolomite, limestone 

breccia, and conglomerate (Imlay, 1944, p. 1117). The limestone of 

the Cohan is overlain in some places by Upper Cretaceous limestone 

and in other places by the Eocene Sepur formation. The lead-zinc ore 

bodies at Caquipec are in the Co ban. 

The structural pattern of the Cohan area is not well known. Sapper 

(1937, pp. 50, 51) has shown that the rocks are folded and cut by 

eastward-trending faults, of considerable displacement, which are par-
LEAD-ZINC DEPOSITs-GUATEMALA 101 

a1lel to the strike of the rocks. In part these faults are normal, but 

some may be thrust faults related to Late Cretaceous and Early Tertiary orogenic movements. 

SAN JOAQUiN MINE 

The San Joaquin mine (fig. 6) is 1% miles by trail south of San 

Cristobal, on the south slope of Cerro Caj 6j, at an altitude of 4,900 

feet. The mine is on the Finca San Joaquin, owned by Edith v. de 

Hesse. It was operated for several years prior to 1920, and a small 

amount of lead is said to have been smelted in a furnace on the 

property. 

The workings consist of two groups of openings, the San Joaquin 

(fig. 6) and Mina Vieja. The San Joaquin workings furnished most 

of the ore mined; they include 2 open pits and about 200 feet of 

underground workings, which explore ore bodies following steep 

fractures that strike N. 55° W. The shallow lower pit shows a few 

irregular pockets of oxidized ore. The upper pit and connecting 

underground workings explore an ore zone 40 feet wide and more 

than 100 feet long. The ore bodies that have been mined are as much 

EXPLANATION 

Lead-zinc 

-ore 

----"'ts_o _ 

Fault, showing dip; dashed where approximately located 

lrrlerred conta~t121 Head of raise or winze 

~ Foot of raise or winze 

> > > > lao 

Inclined workings, chevrons point down 

I I I I I I I 

Opencut 

...L.L.J.L..LL..U...U...LL 

Bench in opencut 

4896' 

Approximate altitude, 

in feet 

0 25 

0 

50 Feet 

10 20 Meters 

FIGURE 6.-Geologic map of the San Joaqufn mine workings, Guatemala. 

4960' 
102 MINERAL DEPOSITS OF CENTRAL AMERICA 

as 25 :feet long and 10 :feet wide and are scattered throughout the 

ore zone over a vertical range of about 70 feet. 

The Mina Vieja workings, a quarter of a mile to the northwest, appear to be along the strike of the San Joaquin workings. Irregular 

underground workings and shallow open pits explore an ore zone 

trending northwestward, 50 feet or more in width, in which the ore 

pockets are erratically distributed throughout. 

SANTO DOMINGO MINE 

The Santo Domingo mine, which is on larid owned by Braulio 

Cuestas, is about 1~ miles southwest of San Cristobal. It isreported 

to have yielded a small, although unknown, amount of lead. The 

workings, in limestone of Permian age which is :for the most part 

highly fractured and highly iron stained, are an opencut 140 feet long 

and as much as 60 feet wide, and several pits and trenches. In 1943 the 

opencut showed little mineralized rock, but low-grade ferruginous lead 

ore was exposed on the north side of the cut. The property was reopened in 1949 by the Compaiiia Minera de Guatemala as a source of 

iron ore :for smelter flux, but only a small tonnage was mined. 

PAMPUJMAY MINE 

·The Pampujmay mine is 3 miles northeast of Tactic, in the Sierra 

Xucaneh. The property is reached by going 2 miles eastward by road 

from Tactic to the Panzos road and then following a foot trail for 

about a mile northeastward. The ore is in the limestone, which strikes 

N. 60° W. and dips 30° SW. 

An open pit about 60 :feet long extends back under a cliff for about 

40 feet. It was originally part of a solution cave in the limestone and 

was enlarged by mining operations and by collapse of the roof. Small 

low-grade pockets of lead carbonate mixed with iron oxide were seen 

on the walls of the cave. Two adits l~ading frmn the pit to underground workings were caved in 1943 and partly filled with waste. 

Other lead -zinc deposits are reported near Santo Domingo, about 

2 miles southwest of San Cristobal, and near Aguas Blancas, 7 miles 

west of San Cristobal on the Rio Chixoy. None of these have been 

explored. 

SEPACAY DEPOSIT 

The Sepacay lead-zinc deposit is on the Finca Buenos Aires owned 

by Esperanza Cortina de Aguilar, 7 miles from Pancajche, the terminal of the Vera paz Railway. Hal£ the distance :from Pancajche to the 

mine is ove.r the Cohan highway, and the remainder is over steep 

mountain trails that rise to a 2,800-foot altitude at the ranch. The 

deposit is a quarter of a mile north of the ranch buildings, at an altitude of 2,925 :feet. The deposit was explored by Manuel and Miguel 

Ocampo about 1930, but no production is reported. 
LEAD-ZINC DEPOSITs-GUATEMALA 103 

The ore at Sepacay is in limestone and dolomite of the Chochal 

limestone and is exposed in a prominent outcrop that trends N. 30° E. 

along the slope. The ore appears to be chiefly smithsonite and cala~ 

mine, accompanied by cerussite and other oxidized lead and zinc minerals. The principal ore body is 30 feet long by as much as 15 feet wide, 

with smaller parallel lenses nearby. As slope wash conceals any extensions of the ore that might be present, further exploration along the 

strike seems warranted. 

· SUQUINAY PROSPECT 

At Suquinay, about 11h miles east of Purulha, boulders of lead 

and. zinc carbonates, galena, and iron oxides form a zone 15 feet wide 

that extends for a distance of 150 feet up the mountain side. Because 

of a widespread soil cover and landsliding in the area, no outcrops 

were seen. The Compaiiia Minera de Guatemala has been carrying on 

exploratory work in the area since 1949, and it is reported that the 

results of the work are encouraging. 

LA CAMELIA PROSPECT 

On the Finca La Camelia, near Purulha, shows of lead and zinc are 

found a quarter of a mile northeast of the buildings. Exposures in 

a field show lead and zinc carbonates with iron oxides in a zone 10-12 

feet wide and 40 feet long that trends N. 20° E. The rest of the zone 

is covered with soil. The Compaiiia Minera de Guatemala is reported 

to have driven an adit 200 feet long under the deposit in 1949, but no 

ore bodies of commercial size were discovered. 

SEQUILHA PROSPECT 

The Sequilha lead-zinc mine is about 15 miles north of Tucuru, on 

the Finca Coyocoo. The property may be reached most easily from 

Cohan by car to the Finca Chajcar, then on horseback southward about 

5 miles to the mine, which is on the trail to Tucuru. Lead and zinc 

carbonates, with a little relict galena, occur in Permian limestone 

and dolomite. 

Several trenches and 2 adits, 33 feet long and 20 feet long, on a 

small knoll rising 60 feet above the valley, explore an ore body that 

trends eastward for about 32·0 feet along a fracture zone. The trenches 

at the east end show lead and zinc carbonates, in places making up 

the major part of the rock over a width of 10-30 feet and extending 

along the strike for about 100 feet. Adit 1 was driven for · 33 feet 

under the outcrop at this place, which is about 20 feet vertically below 

the top of the knoll; the adit shows low-grade ore and barren rock. 

Beyond adit 1 the ore zone continues, but the ore is low grade, containing only erratically distributed veinlets and pockets of lead and 

zinc carbonates. Ae the west end of the desposit another short adit 

shows only low-grade material. 

388364-57-8 
104 MINERAL DEPOSITS OF CENTRAL AMERICA 

Judging from the occurrence of the ore, alteration of the sul~des 

to carbonates must have occurred almost in place. AlthoughJ1etre.the 

ore seems to be shallow, further exploratory work at depth may be 

warranted, for the fractures that localized the ore may well continue 

downward. 

CAQUIPEC MINE 

.. A.t Caquipec, 2~ 1niles west of Sequilha, the Compa:iifa Minera de 

Guatemala since 1946 has been exporing lead-zinc deposits. In-1949 

the company completed a 10-mile section of road which connects the 

mine with San Pedro Carcha and Cohan, thus providing a transportation outlet either by El Rancho, or by the Rio Polochfc and Lago de 

Izabal. A modern camp has been established at the mine and a 100-ton 

mill was put into operation in 1952. The underground workings consist of several thousand feet of tunnels, raises, and crosscuts. 

The ore is said to occur as replacement ore bodies adjacent to fissures in limestone, dolomite, and shale which have been identified 

as the Early Cretaceous Cohan limestone. The fissures strike N. 30° 

E. and dip steeply southeastward. The ore produced at first consisted 

o:f carbonate ore from surface workings, but more recently sulfide ore 

has bee;n reached in the underground workings. The depth of oxidation is about .100 feet. 

SAN SEBASTIAN MINE 

The San Sebastian deposits are about 5 miles by trail north of 

Tucuru, on the Finca Vinaroz, which is owned by the Artola family. 

Lead and zinc carbonates were seen at the San Sebastian deposit at an 

altitude of 5,150 feet and a.t the Sierra de San Sebastian deposit at an 

altitude of 6,350 feet. Neither has been explored. 

The San Sebasti:an deposit, on the south side of a sinkhole, consists of a vein 5 feet in average width that is composed largely of lead 

and zinc carbonates. The vein strikes N. 30° E. and can be traced 

for a distance of 80 feet. A sample of the ore is reported to contain 

15.8 percent lead, 36.7 percent zinc, and 10.3 ounces of silver to the ton. 

The Sierra de San Sebastian deposit is in the cliff-forming limestone 

of the Chochal formation of Permian age that caps the range; the 

limestone strikes N. 80° E. and dips 10°-15° NW. Exposures on the 

slope show fractured limestone containing erratically distributed 

galena crystals. On the whole the rock is of low grade, but in places 

it contains 20 percent or more galena. Exploratory work in the San 

Sebastian area may be warranted. 

MANGANESE DEPOSITS 

Manganese deposits are known in Guatemala, Honduras, Costa Rica, 

and Panama, but only some of those in Costa Rica and Panama have 

been exploited. The production was noteworthy during the 1890's 
MANGANESE DEPOSITS 105 

in Panama and during World War I in both Panama and Costa Rica 

when most of the known deposits of good grade ore were mined. 

Since 1920 there has been little exploratory work. 

COSTA RICA 

The manganese deposits of Costa Rica have been described by Sears 

(1920, p. 61-83) and by Webber (1942, p. 339-345). Roberts (1944, 

p. 387-414) visited the manganese districts in 1942 and brought the 

maps of the deposits up to date. As there had been little activity 

in the area since 1942, no further visits were. made during the present 

study. 

The manganese deposits of Costa Rica are on the Peninsula de 

Nicoya on the Pacific coast, in the Provincia de Guanacaste. Between 

1915 and 1920, nearly 32,000 long tons of high-grade ore was shipped 

kom them to the United States. Attempts were made to put the 

mines in production again in 1943 and 1944, but shipping and loading 

difficulties preve-nted this. 

GEOLOGY 

The rocks of the Peninsula de Nicoya are principally pre-Tertiary 

and Tertiary. The pre-Tertiary rocks are composed chiefly of basalt 

flows-in part pillow lavas-and pyroclastic rocks, with some intercalated sedimentary material. These rocks have been intruded by 

diabase and diorite. The Tertiary rocks include interbedded shale, 

sandstone, and limestone of Eocene and Oligocene age; sediments of 

Miocene and Pliocene age are found in the northwestern part of the 

peninsula and . on islands in the Golfo de Nicoya. The manganese 

deposits are for the most part in pre-Tertiary rocks, but a few of them 

are in Tertiary rocks. 

DESCRIPTION OF THE ORE DEPOSITS 

The manganese deposits are of hypogene, supergene, and residual 

origin. The hypogene deposits are composed of the manganese silicates braunite, bementite, and rhodonite; these minerals occur in 

jasper that has replaced sedhnentary and igneous rocks along the 

bedding and in fault zones. Braunite predominated in ore mined 

from the deeper workings at the Curiol mine. These deposits are tabular, lenticular, or irregular in shape. Some of them are as much as 

120 feet long, 20 feet wide, and 100 feet deep, but their average 

dimensions are smaller. 

The supergene and residual deposits are mainly pyrolusite, wad, 

and psilomelane, which were formed by weathering of the silicate 

1ninerals. These deposits are extremely irregular in form. The depth 

of oxidation ranges from a few feet to more than 75 feet. 

About 1,000 long tons of ore, containing between 30 and 50 percent 

manganese, was estimated to be blocked·out or in the dumps in 1941, 
106 MINERAL DEPOSITS OF CENTRAL AMERICA 

and 1,800 tons may reasonably be expected in extensions of known 

ore bodies. A total of possibly 10,000 tons may be found in known 

ore bodies, extensions of known ore bodies, and new ore bodies that 

were too lean to be worked during World War II. New discoveries 

may even increase these figures considerably, and production might 

reach .20,000 tons if ore containing as little as 30 percent manganese 

is mined. Some of the ore can be sorted by hand or concentrated in 

simple washers; the rest, perhaps more than half of it, will have to 

he crushed and concentrated by more costly methods. 

PANAMA 

By FRANK S. SIMONS 

Manganese deposits are known in five areas in Panama. They 

are Bahia de Mandinga, N ombre de Dios, Rio Boquer6n (Hyatt), 

Calzada Larga, and Bahia de Montijo. Of these the Nomb~~ 

de Dios area has been the most productive, having yielded roughly 

40,000 long tons of high-grade ore. It seems reasonable that ore 

bodies of fair size will be discovered by further exploration, but, since 

mining and shipping costs in Panama are high, the deposits cannot be 

mined at a profit except during the periods of. high manganese prices. 

The manganese deposits of Panama were studied in the field from 

December 1942 to late April 1943 under the program of cooperation 

with the American Republics sponsored by the United States Department of State. The assistance of various officials of the Republic 

of Panama is gratefully acknow I edged, and the cooperation of many 

officers of the Canal Zone and the United States Army, who assisted 

Mr. Simons in many ways, made possible the completion of the work 

during the dry season. 

BAHIA DE MANDINGA AREA 

The Bahfa de Mandinga manganese deposits (fig. 7) are in the 

extreme western part of the Provincia de San Bias, in the low hills 

north west of Bahia de Mandinga at the west end of the Golfo de San 

Bias. The deposits are near lat 9°31' N. and long 79°5' W., in an 

area that is about 60 miles east of the Caribbean terminus of the 

Panama Canal and accessible only by boat and airplane. The Golfo 

de San Bias and Bahfa de Mandinga, although studded with coral 

reefs and islands, are deep enough to permit the passage of large boats 

to within a few hundred yards of the shore in the vicinity of the 

manganese deposits. The surrounding country is sparsely settled, but 

most of the islands in the gulf are inhabited by the San Bias Indians, 

who operate small plantations on the nearby mainland, and there are 

small native settlements at Nicuesa and Mandinga. 
-;.. 

--- ...... 

'1.-0 "V 

.... ---- ..... 2 3-.s-,:,. ·.·:· 

······· ·~··· •. 

. :·:.· 

Outcrop and boulders 

of manganese silicate 

100 0 500 Meters 

I I I I I I I I 

500· 0 1000 Feet 

MINES AND RAILROAD 

""-'~ '-..... /1':.,\ 

Small manganese oxide 

bodies 

. ·' :-:·:·.·.·. 

Manganese oxide outcrop 

and boulders 

~ 

"V,L.. 

MINE NO.2 

~ ~~~ \ 

Manganese oxide boulders 

EXPLANATION 

.::::: __t70 ::::._ 

Shear zone, showing dip 

10 0 50 Meters 

50 0 100 Feet L_o _ _j I ' I I I 

/30 '<.,J-<..J 

Strike and dip of beds Opencut Railroad, 

~ 

abandoned 

FIGURE 7.-Sketch maps of the Bahfa de Mandinga manganese deposits, Provincia de San Bias, Panama. 

I 

~ 

t:::1 

t;j 

"d 

0 

Ul 

8 

Ul 

~ ·~ 

.·~ 

1-l 

0 

-..:t 
108 MINERAL DEPOSITS OF CENTRAL AMERICA 

The Bahia de Mandinga deposits, together with the Soledad deposits 

at Nombre de Dios, are the only manganese deposits in Panama which 

have been in production. 

During 1916 and 1917 the deposits were operated by James Hyatt 

and William Powellson, who exported to the United States 21,309 

long tons of ore valued at $691,488. Some of the ore is said to have 

been worth $104 per ton. Statistics on imports of manganese ore 

from Panama by the United States during the year 1916-19 are given 

in the table below. All this ore was produced from the Mandinga 

mines. 

Manganese produced from the Bahia de Mandinga mines, Panama, 1916-19 

Year Tons Oong) Value (dollars) 

10,498 265,772 

5,202 163, 120 

5,608 262,520 

2 76 

1916 _________________________________________ _ 1917 _________________________________________ _ 

1918------------------------------------------ 1919 _________________________________________ _ 

Total __________________________________ _ 1---------1---------

21,310 691,488 

The ore was mined from many open pits in four general areas. It 

was sorted by hand and then carried by tram from the mines down 

to a railroad, which took the ore to a short pier where it was loaded 

on boats for shipment. The mines have been inactive since 1919. The 

tramline, railroad, and pier are almost completely in ruins; a few 

rusty rails and remnants of ore cars are the only evidence of former 

activity. 

The Bahia de Mandinga deposits examined are estimated to contain 

manganese ore averaging 25 or 30 percent manganese and 40 or 50 

percent silica. This ore is largely in the form of the hydrous manganese silicates bementite and neotocite. The writer heard vague reports of other deposits farther inland in the same general area but 

could find no one who had any accurate knowledge of them. 

GEOLOGY 

The manganese deposits are located on the crest of a low ridge that 

trends about north-northeastward, roughly parallel to the shoreline 

of Bahia de Mandinga (fig. 7). They are all about half a mile inland 

at altitudes of 160-330 feet. 

The predominant country rock is a soft deeply weathered shale or 

mudstone which crops out in a few places along stream courses. On 

the geologic map (pl. 1) these rocks are included in the complex 

group of Cretaceous ( ~) age. Nearly everywhere a thick mantle of 

clay obscures the bedrock, but along the crest of the ridge there are 
MANGANESE DEPOSITS-PANAMA 109 

numerous prominent outcrops of red and yellow jasper; shale is exposed near the jasper at a few places, mainly in prospect pits. 

DESCRIPTION OF THE ORE DEPOSITS 

The manganese ore in the Bahia de Mandinga area is closely associated with red and yellow jasper. This rock is fine grained, massive, 

and entirely devoid of bedding. It is considerably jointed and 

faulted, and the few visible contacts of shale with jasper appear to be 

faults. The jasper has probably been produced by silicification of 

shale or mudstone, either along the bedding or in shear zones. 

Most of the manganese oxide is very hard and heavy psilomelane, 

but small quantities are soft and powdery. It appears to have replaced the jasper along faults and fractures, for the ore bodies are 

elongate and irregular and often contain masses of jasper surrounded 

by oxide. The writer was told by men who had, worked in the mines 

that the ore bodies mined were usually small and difficult to separate 

from the jasper . 

.At_ mine 4, manganese silicate, either bementite or neotocite, has replaced jasper and has been slightly oxidized where exposed at the 

surface. No hypogene replacement bodies of manganese oxide were 

seen at mine 4, but at mine 2 the oxide has replaced the silicate to a 

small degree. The complete paragenesis is not shown at any one locality, but the sequence appears to be: 

)'!Manganese oxide 

Shale--+ Jasper< )'!Oxide (replacement) 

~Manganese silicate( 

~Oxide (surficial) 

Wherever both manganese oxide and manganese silicate are present, 

the oxide appears to be later than the silicate. 

The manganese deposits described below are in the order of their 

occurrence from southwest to northeast. • , 

RIO NAVAGANA DEPOSITS 

Manganese ore crops out about a mile from the mouth of the Rio 

N avagana on both sides of a small tributary. On the northeast side 

of the stream the outcrop is about 130 feet long and 10-16 feet thick. 

It strikes about N. 50° E. and is vertical. .About 200 feet southwest 

across the creek there is a small outcrop of ore approximately parallel 

to the main outcrop. No ore is exposed between the two outcrops, 

and the ore body is probably not continuous. The wall rock, exposed 

in three shallow pits, consists of shale whose attitude is uncertain. 

The manganiferous material is almost entirely a brown manganese 

silicate, but it includes a very small amount of manganese oxide, all 

of which appears to be at or near the surface. Probably at least 5,000 
110 MINERAL DEPOSITS OF CENTRAL AMERICA 

long tons, and possibly as much as 10,000 long tons, of ore that will 

average not more than 30 percent manganese and not less than 50 

percent silica is available, but the low grade of the ore and the predominance of manganese silicate make the deposits worth little now. 

MINE 1 

Mine 1 is about half a mile northeast of the Rio Navagana deposits. 

Development work consists· of an opencut 165 feet long and 80 feet 

deep, heavily overgrown with jungle. The walls of the cut were so 

steep that they could not be climbed for insp®tion. 

Most of the rock exposed is red or brown jasper cut by numerous 

small quartz veins. The only ore in sight was a flat-lying seam, 1%-3 

· feet thick, of high-grade hard manganese oxide in the lower face· of 

the cut. The wall rocks are considerably sheared and the ore seems 

to have been deposit~d along a shear zone. 

MINE 2 

Mine 2, the largest one at Bahia de Mandinga, lies about 1,640 feet 

northeast of mine 1 on the crest of the ridge. The workings, all-open-

~uts, cover an area 390 feet long by 250 feet wide and reach a maximum 

depth of 80 feet (fig. 7). Although some of the cuts are .completely 

overgrown with jungle, the mine affords by far the best exposure in 

thearea. · 

The rock exposed in the cuts is largely red and yellow jasper, which 

in places is considerably sheared and brecciated. In the northwestern 

part of the mine area there is an outcrop of shale or mudstone. Deep 

weathering has nearly obliterated the bedding, which appears to strike 

nearly northeast and dip about 30° SE. The rock is closely jointed 

and weathers into tiny irregular red, yellow, or gray columns and 

pinnacles. The jasper in this mine probably formed by silicification 

of an argillaceous rock, and in this locality the silicification apparently 

• worked along the bedding of the shale. 

The ore consists largely of hard blue-black psilomelane, but there 

is also a small amount of soft coarser grained oxide material. The 

oxide occurs as thin veins in jasper and as irregular lenticular bodies 

replacing jasper. One lens of ore contains some brown manganese 

silicate that is partly replaced by manganese oxide. 

The predominant shearing in the jasper has a northeastward trend, 

and the general northeastward course of the workings indicates that 

this is also the trend of the ore zones. It appears likely that ore 

deposition was controlled, at least in part, by shear zones, but postmineralization shearing has occurred to such an extent that all premineralization structures are obliterated.· 

At least 1,000 long tons of high-grade oxide ore is probably available 

in this mine, some of it in place and the rest occurring as float on the 
MANGANESE DEPOSIT8-PANAMA 111 

southeast side of the ridge. However, any ore mined would have to 

be carefully hand sorted. 

MINE 3 

Mine 3 is on the north side of the ridge, about 650 feet east of mine 2. 

Development work consists of a semicircular opencut about 165 feet in 

diameter and 65 feet deep. The rock exposed is jasper, which is red, 

orange, or yellow in fresh exposures and is commonly weathered 

yellow. The deposit has been virtually mined out, the only ore in sight 

being a 6-inch seam of hard manganese oxide that occupies a brecciated 

zone in jasper. The ore has partly replaced the breccia fragments, 

some of which are entirely surrounded by manganese oxide. 

MINE 4 

Mine 4 lies on the crest of the ridge, about 490 feet southeast of 

mine 3. Very little mining has been done, and the only exploratory 

work consists of a few shallow prospect pits. The wall rocks are not 

exposed in the vicinity. The deposit is a lens of manganese ore about 

330 feet long and 15-25 feet thick, striking about N. 70° W. and 

dipping vertically. The ore is largely brown manganese silicate, 

which is oxidized to shallow depths. It is cut by numerous quartz 

veins as much as half an inch in thickness and is somewhat faulted and 

brecciated. Some of the ore contains small fragments of jasper surrounded by manganese silicate, which appears to have replaced the 

jasper. 

Probably at least 10,000 long tons of ore is in place, with an average 

grade of 25 percent manganese and about 50 percent silica, and at 

least 5,000 tons of similar ore is in boulders scattered over the northeast side of the ridge. Some of these boulders weigh more than 10(} 

tons. Because of the low grade of the ore and the predominance of 

manganese silicate as the ore mineral, the deposit has little commercial 

value. 

NOMBRE DE DIOS AREA 

Manganese deposits in the hills south of N ombre de Dios, a small 

town on the north coast of Panama about 30 airline miles northeast of 

Colon, lie between lat 9°30'-9°35' N. and long 79°33'-79° W. in the 

Provincia de Colon (fig. 8). 

N ombre de Dios is on the south shore of Bahfa N ombre de Dios, a 

semicircular open bay about 38 miles by boat from Colon. The town is 

separated into two parts by a channel excavated by dredges at the time 

of the building of the Panama Qanal; the sand was used in the construction of the Gatun locks. During the dry season, from January 

until May, the bay is swept by the trade winds and .may become very 

rough. At such times the only safe anchorage is at Playa de Damas, 

about 11h miles north-northeast of the town. From Nombre de Dios 
112 MINERAL DEPOSITS OF CENTRAL AMERICA 

79°35' 79°30' 

c A R Of B B ECJ.A N D 

EXPLANATION 

Mangan:se deposit 

Railroad (abandoned) 

Trail 

·------------ g~,o 

6 Kilometers 

5 Mllee 

FIGURJII 8.-Manganese deposits in the Nombre de Dlos and Rio Boquer6n areas, Provincia 

de Col6n, Panama. 
MANGANESE DEPOSIT8-PANAMA 113 

trails lead to Porto· Bello, 13 miles to the west, and to several small 

villages along the coast to the east. 

The N ombre d~ Dio& area has a very heavy rainfall, 1;he yearly 

average being about 160 inches; most of which falls between May and 

December. During the rainy season the Rio N ombre de Dios and Rio 

Faro ·are navigable by small boat for many miles; during the rest of 

the year this type of travel is impracticable. 

N ombre de Dios has been closely connected with mangane$ ~ning 

in Panama since the indust:cy's beginning, about 66 years ago.. In 1895 

the Caribbean Manganese Co. built a narrow-gage railroad from Playa 

de Damas to the Soledad mine, south of Viento Frio, and between 

1895 and 1902 it shipped about 40,000 tons of high-grade ore. Political 

unrest, culminating in Panama's secession from Colombia in N ovember, 1903, led to the closing of the mines, and the railroad has been 

abandoned ever since. 

In 1920 the Hyatt Panama Manganese Co. began construction of a 

narrow-gage railr()ad from the west side of the bay to their Hyatt 

no. 2 mine on the Rio Boquer6n, 15 miles to the south. Before the 

railroad was completed the line was abandoned, and it now· serves as 

a trail to the Rio Boquer6n and Madden Lake. 

GEOLOGY 

The plain south of N ombre de Dios is drained by the Rio N ombre 

de Dios and Rio Fat6. Many low hills rise from the plain, and the 

foothills of the Cordillera de San Bias are reached about 2 or 3 miles 

inland. 

The areal geology has not been thoroughly studied, but a few 

generalizations can be made. The rocks are largely sandstone and 

shale, which on the geologic map (pl. 1) are included in a unit classified by Thompson as of Cretaceous(~) age. In a few places limestone 

and tuff were seen. These rocks are more or less flat lying near the 

coast; farther inland the dips become generally steeper, although 

usually less than 45°. In general the sedimentary rocks dip southward, at least wherever attitudes were observed in the vicinity of the 

deposits. No intrusive rocks were seen in place, but diorite float was 

found near Blaque Peak, and igneous rocks may form the cores of 

some of the high peaks. All the deposits examined except the Mariana 

are in the watersheds of the Rio E"at6 and Rio N ombre de Dios. 

MINES ALONG THE Rfo FATO. 

MOSTRONCOSA DEPOSIT 

The Mostroncosa deposit is on the steep hill between Quebrada 

Mostroncosa and Quebrada Mostroncosita, about half a mile south of 

the confluence of Quebrada Mostroncosa and the Rio Fat6 and 3 miles 

south of N ombre de Dios. 
114 MINERAL DEPOSITS OF CENTRAL AMERICA 

The hill is blanketed with angular boulders of jasper and chert in 

clay. No rock in place was found, but the source of the boulders must 

be near the hilltop, as they cover the entire north and east slopes. The 

area of float is roughly 650 feet in diameter. Although some of the 

boulders contain small quantities of partly oxidized manganese sili ~ 

cate, not more than 20 percent of the manganese is present aS oxide. 

The writer was told by his guide that a similar deposit lies farther 

south, but owing to bad weather it was not examined. The Mostroncosa deposit is believed to have little or no commercial value because 

of the extremely low grade of the material available. 

MANGUE DE INDIO PROSPECT 

The Mangue de Indio deposit is about 5 miles south of N ombre de 

Dios, in the low hills along Quebrada Mangue de Indio. A body of 

very siliceous manganese oxide, 80 feet long and 7 feet in average 

thickness, crops out along the bank of a small fork of Quebrada Mangue de Indio. It strikes N. 70° E. and dips 55° SE. ·The wall rock is 

rusty-colored clay containing fragments of tuff or shale. The manganese occurs in thin veins of soft oxide and numerous small rosettes 

of crystalline pyrolusite. Remnants of tuff.in the jasper indicate that 

jasper has replaced tuff. 

The hill to the south is covered with boulders, which are embedded 

in clay. The boulders are composed· of rock varying from a coarsegrained quartzitelike mixture of manganese silicate and quartz to finegrained chert of similar composition; many of them are nearly pure 

chert. Some of the boulders have small rosettes of pyrolusite, and the 

more manganiferous ones are coated with layers of manganese oxide 

as much as 2 inches thick. 

The hill is capped by a flat bed of manganiferous jasper or cherty 

manganese silicate which is about 7 feet thick and covers an area o:f 

270 square feet. Joint and fracture faces in the rock are filmed with 

manganese oxide, but no significant amount of oxide was seen. A 

similar flat bed 170 feet to the south crops out along a canyon wall for 

70 feet ; the bed is about 1 feet thick and consists entirely 'of very 

low grade manganiferous jasper. It has been explored by several 

trenches, which have uncovered no good ore. . 

PANAMA (VENTURA) PROSPECT 

The Panama, or Ventura, prospect is on the southwest bank of 

Quebrada Ventura, a small tributary of Quebrada Macho about 1,640 

feet southwest of the Mangue de Indio deposit. 

An area about 330 feet in diameter is blanketed with boulders of a 

siliceous rock that is either manganiferous jasper or a mirture of 

jasper and manganese silicate. Several shallow trenches show a manti~ 

more than 3 feet thick of boulders embedded in clay, but they expose 
MANGANESE DEPOSITs-PANAMA 115 

no rock in place. Although the boulders are cut by veins of manganese 

oxide, none of them contains more than 20 percent manganese; the 

average is about 15 percent, largely in the form of manganiferous 

jasper or manganese silicate. 

MACHITA DEPOSIT 

The Machita deposit is on a small branch of Quebrada M~cho, about 

a mile from the Rio Fat6 and 2,300 feet southwest of the Panama 

deposit. 

Interbedded shale and sandstone are exposed along the stream. The 

strike varies from northeast to east, and the dip ranges from 20° 

to 40° southeast and south. An area of about 32,300 square feet on 

the northwest side of the creek is sparsely covered with boulders of 

manganese oxide and jasper; some of the jasper is cut by veinlets of 

manganese oxide and by quartz veins as much as an inch thick. Near 

the top of the float area is an outcrop of jasper that strikes N. 25° E. 

and dips 55° NW. Just below the outcrop is an area of about 1,100 

square feet showing some float of fairly good oxide. 

The best material is a rock in which jasper has been largely replaced 

by manganese oxide. The jasper probably formed by replacement of 

shale or sandstone,.but no mangan:ese:~siHcltte has been definitely identified at this deposit. No outcrop of the oxide has been found, but oxide 

in place is probably concealed near the small area of float. 

BLAQUE PROSPECT 

The Blaque prospect is 8 miles southeast of N ombre de Dios on a 

low ridge between Quebrada Blaque and the Rio Fat6. Two shallow 

pits 16 feet ap~rt have been d1,1g_ about 165 feet above the Rio Fat6. 

The pits· expose small bodies of 'jasper cut by veinlets of'inanganese 

oxide, in clay country rock. The rocks strike northeastward and dip 

35 ° SE. Some of the material exposed in the east pit contains about 

40 percent manganese, but the amount of this material is very small. 

Fifty feet to the southwest another pit shows. a sn;>.al~ boulder of siliceous oxide, and the slope below, toward the Rio Fat6, shows a few 

.small boulders of similar rock. A few pieces of diorite were found near 

the base of the hill. 

Two hundred and thirty feet to the southwest, on the northwest side 

of Quebrada Blaque, is an area of about 5,400 square feet covered with 

boulders of brown chert embedded in clay. Some of the chert is cut 

by thin parallel veins of quartz. A few small pieces of mixed manganese oxide and clay were seen, but most of the rock contains little 

or no manganese. 

Just south of the float-covered area, Quebrada Blaque has cut 

through a bed of coarse-grained arkosic sandstone that strikes N. 60° E. 

and dips 45° SE. Bedding surfaces in the sandstone are covered with 
116 MINERAL DEPOSITS OF CENTRAL AMERICA 

plates of chlorite as much as an inch across. A part of the sandstone 

has been replaced by a vein of jasper af'least 8 feet thick; the contact 

between j-asper and sandstone is very irregular but sharp, and dips in 

the opposite direction to the sandstone. 

Practically no ore in place is exposed anywhere on the Blaque 

claims, and the scarcity of manganese oxide in the float indicates that 

there are probably no deposits of any size in the area. · 

LA n!ESA PROSPECT 

The La Mesa prospect is about 5 airline miles and 9 miles by trail 

south of N ombre de Dios on a broad ridge on the west flank of Mesa 

Peak. It lies between Quebrada Mesa and Quebrada Moro, nearly 2 

miles southeast of the junction and 490 feet higher. The trail from 

the junction follows a steep narrow ridge on which limestone boulders 

were seen at 3 places-1,480, 2,460, and 2,560 feet northwest of the 

deposit. Tightly folded shale crops out in a small canyon to the southwest. These were the only rocks except clay seen in· the vicinity of the 

deposit. · 

Manganiferous rock is found near the junction of a broad ridge 

that trends southeastward and two narrow ridges that trend north~ 

westward and southward. At the junction, 2 pits, both about 3 feet 

deep, reveal fragments of manganese oxide and jasper as much as 3 

feet in diameter, embedded in clay. A trench 26 feet to the southwest reveals a mantle about. 12 inches thick of manganese oxide fragments, lying in and on clay; about 10 percent of this mantle is manganese oxide. The manganese-bearing rock is largely sugary 

brown manganiferous jasper or manganese silicate, the smaller frag:-

ments of which have been well oxidized. The large boulders have 

cores of unaltered siliceous material. The best material seen contains 

about 35 percent manganese, but there is very little of it in sight. 

On the northwest ridge, 130 feet from the pits, a shallow trench 

shows a few boulders of siliceous oxide and jasper in clay. Fragments 

as much as 12 inches in diameter make up about 10 percent of the 

surface mantle to a depth of 2 feet. A few pieces of float are found 

in the area between the pits and the trench. Just northwest of the 

trench are a few boulders of siliceous manganese oxide, and to the east 

is an area of about 1,100 square feet covered with similar boulders. 

The largest area of float is about 100 feet east of the pits, on the west 

side of a small canyon. Here a narrow bench is covered with boulders, 

weighing as much as several tons each, over an area 115 feet long by 65 

feet wide. The float is mostly jasper and slightly oxidized manganese 

silicate or manganiferous jasper. No rock definitely in place was seen; 

the area is completely unexplored. The ground between this area and 

the ridge top is practically devoid of float. Several tons of rock averaging about 15 percent manganese are in sight here and on the steep 
MANGANESE DEPOSITs-PANAMA 117 

slope below, but lack of outcrops makes it impossible to predict that 

any more will be found~ 

CERRO VIEJ'O DEPOSITS 

Three deposits, the America, Maria Defense, and June, are found 

near the summit of Cerro Viejo, a prominent hill5 airline miles southwest of N ombre de Dios. Cerro Viejo is 4 miles by trail from the 

nearest point on the abandoned Hyatt Railroad and 81h miles by trail . 

from Nombre de Dios. It is reached by traveling south along the 

railroad to a point just south of the junction of Quebrada de Pavos 

and Brazo de Cedro, from which a trail leads over a low divide back to 

Quebrada de Pavos and from there to the foot of Cerro Viejo. Cerro 

Viejo can also be reached from Garrote by taking the Ferrari banana 

railroad to the Rio Indio, from which a trail is said to lead to Quebrada 

de Pavos, but this route is longer and perhaps more difficult. 

Just downstream from the old Pavos mining camp is an outcrop of 

thickbedded purplish shaly limestone that strikes N. 70° W. and dips 

25° SW. Near the camp is a very siliceous 5-ton boulder which has 

probably come from the America deposit on the ridge above the camp. 

AMERICA PROSPECT 

The America prospect is on Cerro Viejo, about 400 feet southeast 

of the mining camp, which is at an altitude of 260 feet. The altitude 

of the deposit is 460 feet at the north end and 575 feet at the south 

end. The area. has been cleared, but no other evidence of prospecting 

was seen. 

The deposit consists of boulders of very siliceous manganiferous 

rock, in clay, along the steep narrow crest of Cerro Viejo. As the ridge 

is very steep, there has been little opportunity for the accumulation of 

a large amount of float. The boulders at the north end of the area 

are largely a quartzitelike rock composed of an intimate mixture of 

jasper and manganese silicate or manganiferous jasper. Most of 

them are coated with a thin film of manganese oxide. No good oxide 

ore was seen, the average manganese content of the boulders being 

only 10 or 15 percent. 

The boulders can be traced southeastward and southward along the 

ridge crest for 400 feet. Near the south end are two concentrations 

that probably mask the site of a concealed body of manganiferous 

jasper. At the extreme south end is a small area of float of soft crystalline manganese oxide averaging about 45 percent manganese, but 

no outcrop of this material was found. 

MARIA·DEFENSE PROSPECT 

The Maria-Defense prospect is about half a mile south of the America deposit, on the crest of Cerro Viejo at an altitude of 1,000 feet. 

It lies about halfway behYeen Cerro Viejo and a slightly lmYer 

summit to the north. 
118 MINERAL DEPOSITS OF CENTRAL AMERICA 

An area about 100 feet long and 65 feet wide has been thoroughly 

cleared and scraped. Two outcrops of manganese oxide are exposed; 

the north outcrop has an area of 180 square feet and the south outcrop 

covers about 130 square feet. The centers of the outcrops are 60 feet 

apart, and the intervening ground shows a light mantle of float but no 

outcrops. A shallow trench just north of the south outcrop shows 

numerous small fragments of manganese oxide in clay, and a trench 

· along ·too east side of the outcrop shows a thin irregular lay~r of j~­

per, 1-12 inches thick, between oxide and clay. The jasper is cut by 

quartz veins. An opencut below the outcrop shows an 8-foot vertical 

face of manganese oxide containing some admixed clay and a few 

small pockets of brown jasper. Just below the cut is a 10-ton boulder 

of jasper, which may have rolled down from the hill 300 feet to the 

north. This boulder and smaller ones nearby are cut by many veinlets 

of quartz. 

The manganese oxide is largely soft crystalline material that shows 

much variety. Most of the oxide is finely crystallized, usually containing bundles of radiating prisms of pyrolusite as much as half an inch 

in length. Some of the material is finely banded with thin layers of 

quartz and manganese oxide. At the ~outh end of the north outcrop 

the .rock is a hard mixture of crystalline oxide and quartz full of stnall 

vugs which ar_e lined with tiny quartz crystals and striated cubes or 

short prisms <Of a manganese oxide, probably pyrolusite. The oxide 

appears in general to contain considerable silica, largely free. Some 

of the pebbles of oxide found in the clay appear to have formed in 

place; they have the typical irregular rounded shapes of small concretions and show a roughly concentric structure, with crystalline cen.., 

t~;rs-;and. m.R-ssi ve rims. 

Little can be said about the origin of the manganese oxide, because 

there are few exposures of anything but oxide and clay. The south 

outcrop, which shows isolated irregular pockets of jasper sur,rounded 

by oxide, and a~so a belt of jasper along the east contact with clay, 

suggests that the jasper has been at least in part replaced by manganese oxide. The origin of the. jasper is not known,. but, to judge 

from similar deposits in other parts of Panama, it may have replaced 

shale or tuff, the unreplaced part of which is now altered to clay. 

On the steep slope north and west of the main outcrops are several 

bouldeTs and one outcrop of purplish manganese silicate or manganiferous-chert. Some of the rock has been brecciated, and the fragments are cemented by veinlets of quartz and chalcedony. A few boulders in the opencut northwest of the north outcrop have been well 

oxidized, but most of them carry little manganese. The Maria-Defense deposits are considered the best of those examined in the Nombre 

de Dios area, since they are the only ones in which an appreciable 
'MANGANESE DEPOSITS-PANAMA 119 

amoUnt of good oxide ore was seen. The area between the two outcrops and also to the north of them should be deeply trenched, in order 

to establish whether the outcrops are connected and whether there is 

an extension-of the ore body northward. Until this is done, the deposits must be considered as no more than fair prospects. 

MARIANA DEPOSIT 

The Mariana deposit is on Quebrada Mariana, which flows into 

Bahia de Indio 31;2 miles west of N ombre de Dios. It is most easily 

reached from Nombre de Dios by way of the Hyatt Railroad and 

Quebrada Marianito, a distance of 4 miles. 

Numerous small fragments of manganese oxide are found on a low 

ridge west of Quebrada Mariana, and a boulder weighing about a ton 

lies in the creek. This boulder is mentioned in several earlier reports 

and has evidently furnished material for several assays. Float ore is 

found over an area about 230 feet long and 100 feet wide, but at o~ly 

!locality near the west end of the area was any ore seen that might 

have been in place. Several trenches show fragments of manganese 

oxide in clay that contains small pieces of decomposed shale; the 

fragments are found to depths of 3 feet but in no great concentration. 

Near the center of the area a concentration of small boulders suggests 

an undiscovered ore body nearby. 

The oxide is a massive finely crystalline hard black mineral of the 

psilomelane type, cut by thin veins of pyrolusite. The massive oxide 

contains numerous small vugs filled with tiny striated prisms pf 

pyrolusite. The oxide contains on the average about 45 percent manganese. · Much of the float shows pockets of clay from which the oxide 

has been removed by leaching. 

JUNE PROSPECT 

The June prospect is on a bench high above Quebrada Luis, on 

the east side of a small tributary of that stream, where an area about 

250 feet long by 165 feet wide has been cleared. Well-bedded shale 

and sandstone striking north and dipping 25° W. crop out in the west 

wall of the canyon. The area is strewn with numerous large and 

small boulders of red and brown jasper cut by veinlets of quartz. One 

outcrop of jasper, 50 feet long and more than 10 feet thick, is found in 

the cleared area. The jasper strikes north, but its dip is uncertain. 

Some of it is manganl.ferous, many boulders of it being coated with 

manganese oxide, but all the material in sight is of very low grade. 

HYATT AREA 

The Hyatt manganese deposits are about 28 miles east-northeast of 

Colon, in the Provincia de Colon on the west side of the Rio Bo388364-~7-9 
120 MINERAL DEPOSITS OF CENTRAL AMERICA 

quer6n, which flows into the extreme north end of Madden Lake (fig. 

8). The no. 1 mine lies at lat 9°23' N. and long 79°34' W. between 

2 forks of Mine Creek, a small tributary that enters the Rio Boqueron 

from the west about 4 miles from its mouth. The no. 2 mine lies at 

lat 9°27' N. and long 79°33' W., on a high ridge between the Rio 

Boqueron and the Rio Candalosa, about 5 airline miles north-northe~st of the no. 1 mine. The distance along the Rio Boqueron between 

the·2 mines is about 5 miles. 

The deposits can be reached from Panam,a or Colon by way of 

Madden Lake. The recently completed Trans-Isthmian Highway, 

which connects Panama with Colon, skirts the south end of Madden 

Lake at Madden Dam. The Rio Boqueron enters the lake about 13 

1niles north of the dam and can be reached by launch. The river is 

navigable by small power boats for about a mile and a half from its 

mouth; beyond this point are many rapids which can be traversed 

only by native canoe. During the dry season, from January until 

April, the Rio Boqueron may at times be so low that even canoe 

travel is difficult. 

The deposits can also be reached by trail from N ombre de Dios, a 

small village on the north coast of Panama about 34 miles by boat 

northeast of Colon. The no. 2 mine is about 15 miles south-southwest 

of N ombre de Dios, and the no. 1 mine is about 5 miles farther south. 

The trail follows the route of the old Hyatt Railroad. 

The Hyatt deposits are in a deeply dissected, rugged terrain of 

deep, narrow canyons and sharp ridges. The highest point in the 

vicinity is Cerro de La Bruja, 3,200 feet in altitude, on the divide 

between the Rio Chagres drainage basin and the Caribbean slope. The 

maximum relief at the no. 1 mine is 260 feet and at the no. 2 mine, 

it is 400 feet. 

The Hyatt deposits were discovered about 1915 and in 1917-18 

were explored briefly under the direction of James Hyatt. In 1920 

the Hyatt Panama Manganese Co. was organized, and a narrow-gage 

railroad was built from the west side of Bahia N ombre de Dios to 

within a mile of the mouth of the Rio Candalosa. The railroad is 

16 miles long and crosses a gap in the divide at an altitude of 885 feet. 

Maintenance of the road in this rough country of heavy rainfall 

proved so difficult that the line was abandoned a few years later. In 

1942 the railroad was in complete disrepair; all the bridges, of which 

there were a great number, were useless, and much of the track had 

been buried by landslides. The rails were in fair condition, but many 

of the ties were completely rotted away. 

The only ore produced by either mine is a few tons said to have 

been taken from the no. 1 mine and shipped by small boat to Colon 

for assay. 
MANGANESE DEPOSIT8-PANAMA 121 

HYNI'T NO. 1 MINE 

The Hyatt no. 1 mine is on a steep asymmetrical ridge between two 

forks of Mine Creek, about half a mile west of the Rio Boqueron (fig. 

9). Most of the area is covered with red and brown clay, but along 

the north fork are many exposures of fine-grained gray and white 

quartzite that shows no bedding. This rock is overlain by a deeply 

weathered gray schist, which strikes north and dips 45° W. The 

contact is not exposed but is probably near the headwater fork of 

Mine Creek, just north of the main ore body. Near this ore body 

several pits expose a highly micaceous schistose gray rock containing 

numerous round and elongate nodules of pink and gray sandy material. This rock, which is thought to be a metamorphosed tuff, forms 

the walls of the deposit. The rocks are probably pre-Eocene in age. 

The main outcrop exposes a sheet of manganese oxide that strikes 

northwestward, dips 50° SW., and forms a dip slope on the south side 

of the ridge. Its visible thickness ranges from 3 to 10 feet and is 

assumed to average about 7 feet. The position and shape of the,outcrop·are shown on the map (fig. 9). On the ridge below the outcrop is 

a. heavy blanket of float, which extends all the way down the canyon 

to the fork. Two parallel trenches, each 100 feet long, are cut through 

the crest of the ridge. The upper edge of the oxide sheet is shown in 

place at the south end of each trench, where the manganese oxide is 

in contact with jasper and appears to have partially replaced it. Elsewhere both of-the trenches are in clay and jasper which are cut by a 

few thin stringers· of manganese oxide. The cltl,y was probably 

formed by the weathering of the schistose rock exposed in nearby pits. 

The ore is hard blue-black psilomelane-type ma.terial containing 

numerous small pockets of soft oxide, and along the west side of the 

outcrop there are pockets of rhodonite and piedmontite. ·Some of the 

ore, especially at the south end of the west trench, is crudely banded 

with alternate layers of manganese oxide and quartz~ The oxide is 

generally somewhat siliceous and averages about 40 percent manganese. The outcrop covers an area of 5,800 square feet and has an assumed average thickness of 7 feet, thus containing about 3,000 long 

tons of ore. .Also, 500 tons of similar rock crops out on the slope 

below this outcrop and along the canyon bottom . 

.A hundred feet northeast of· the main outcrop is another, which 

strikes N. 30° W. and dips 70° SE. This outcrop is 3.3 feet long and 

as much as 7 feet thick but pinches out at both ends. .A pit on the 

southeast side shows solid oxide, in contact with red clay, to a depth 

of 16 feet. The oxide is hard, pure, psilomelane-type material, which 

appears to be of somewhat higher grade than that of the main outcrop. 

Three hundred tons of this material is in sight and as much more can 

be expected. Numerous boulders of similar oxide lie on the flat area 
·~~ ~ ~ z (.) 1.1.1 ;:: 

::3 1.1.1 

0: z ...., ~ 

.lE 

10 0 50 Meter~ 

50 0 200 Feet 

Contour lntervallO meters 

Dll.tum is approximate sea level 

EXPLANATION 

Outcrop 

-

of manganese oxide 

20• .a.l 

Manganese oxide boulders; numbers indicate weight in tons 

~!-=-~2i{:t] Manganese oxide float 

Float boundary 

~ 

Strike and dip of beds 

"\.t.,Je~ Opencut, pit, or trench 

X,Y 

FIGURlll 9.-Map of the Hyatt no. 1 manganese mine, Provincia de Col6n, Panama. 

....,a 

~ 

t..:> 

pj 

~ E=i· 

t1 

l:;1 

ttl 

0 

~ ci 

l:lj 

i 

~ 

s 

~ 

~ 
MANGANESE DEPOSITs-PANAMA. 123 

below. the outcrop; 1 boulder weighing about 35 tons has been exposed 

on 2 $ides by trenches and is embedded in clay that contains numerous 

fragments of manganese oxide to a depth of nearly 3 feet. 

Other shows of manganese in and near the no. 1 . mine consist of 

2 ·elongate areas of float, 1 extending 400 feet north from the .main 

outcrop and the. other trending about east-northeastward. down the 

main ridge to Mine Creek, a distance of about 650 feet.. The area 

between these two tongues is nearly devoid of float. The np:ftQ:wardtrending tongue ranges in width from 100 to 165 feet and contams only 

widely scattered float. A few large boulders weighing as m.;u.ch as 

15 tons are found on the slope immediately below the ridge wp. and. 

were probably derived from the main outcrop. At the bottom of the 

hill, on the south side of Mine Creek, is a heavy concentration ,of 

boulders of manganese oxide in an area of 29,000 square feet. These 

boulders,some of which weigh as much as .5 . .tons, probably,:represent 

a small eroded nearby outcrop, for the slopes above are practically. 

barren. The boulders have cores of dark-brown mangane$6. sili,cate 

surrounded by hard oxide that contains small pockets of porous silica, 

which may have been freed by the oxidation of the silicate. The material is not high grade, averaging only 30-35 percent manganese. 

Several hundred tons is in sight, and exploration by trenching:.near 

the upper end of the float area might uncover the parent ore body. 

The rest of the north slope is only sparsely covered with flo-at, and no· 

other concentration suggesting an undiscovered ore body was found.. 

The eastward-trending tongue shows considerably more float. Some 

800 feet northeast of the main outcrop (X on fig. 9), many boulders 

that weigh as much as 15 tons are found in an area of about 500 square 

feet. The boulders consist of hard oxide mixed with considerable 

free silica and appear to be of lower grade than the material from 

the ore body to the west. They may represent the eroded outcrop of 

another small ore body. The average grade is perhaps 35 pereent 

manganese. 

At point Y on the map there are several boulders of manganese 

oxide on the crest of a narrow ridge trending northeastward, and from 

this point a train of boulders extends eastward and southeastward 

nearly to Mine Creek. These boulders have probably come from an 

ore body, somewhere near pointY, that is either concealed or completely eroded, for the area between X and Y is nearly barren of float. 

Some of the boulders contain a mixture of high-grade oxide and oxide 

containing a little free silica; others are mixtures of jasper and oxide, 

and 1 boulder, weighing about 100 tons, consists entirely of banded 

green and gray jasper. Most of the boulders, however, are -mainly 

hard bluish-black manganese oxide and average 40 per cent manganese. An area of 21,500 square feet is more or less covered with these 
124 MINERAL DEPOSITS OF CENTRAL AMERICA 

boulders. In Mine Creek just above the forks on the east side of 

figure 9 is a boulder of hard oxide, weighing about 100 tons, whose 

source is unknown. 

The main outcrop appears to be chiefly manganese oxide and finely 

crystallized rhodonite but contains scattered crystals of piedmontite 

and a few isolated patches of some carbonate, probably manganiferous. The origin of the rhodonite is not known; in the one thin section examined it appears to replace a carbonate. The rhodonite-piedmontite rock was seen at only a few places along the west side, and 

the deposit is thought to consist almost entirely of oxide. The siliceous 

nature of the oxide suggests that it may have originated by the oxidation of a manganese silicate such as rhodonite, which may either 

in turn have been formed by metamorphism of a vein or bed of 

manganese carbonate or be a primary hydrothermal mineral. 

No manganese minerals other than oxides were seen anywhere else 

in the area except in the boulders near Mine Creek north of the main 

outcrop; these are composed of a dark-brown partly oxidized manganese:ailicate, either bementite or neotocite. 

HYATT NO. 2 MINE 

· The Hyatt no. 2 mine (fig.10) is divided into two parts by the high 

ridge between the Rio Boquer6n and Rio Candalosa (the use of this 

name follows the nomenclature of the U.S. Army Engineer map of 

the Pequeni quadrangle; other reports have called this river the 

Diablo, which is shown on the Army map as entering the Boquer6n 

several miles farther north). The south deposits are near the headwaters of Manganese Creek, a small tributary of the Candalosa, and 

the north deposits are at the headwaters of Copper Creek, which flows 

into the Ri(} Boquer6n. As at the no. 1 mine, the area is blanketed 

with a thick cover of clay, and the few outcrops are either along 

stream courses or in pits near the deposits. .1\:long the~ Rio Boq_uer6n 

above and below the mouth of the Candalosa are exposures of thinbedded siliceous gray limestone, which is tightly folded and contorted 

l?ut in general strikes northeastward and for the most part has steep 

dips. Along Manganese Cresk are outcrops of sheared greenish 

l).ighly altered volcanic breccia. The breccia fragments are largely 

amygdaloidal andesite in which the amygdules are composed of 

calcite, limonite, and green opal. The breccia strikes northeastward 

and dips 40°-65° SE. It is in contact with shale about 230 feet from 

the mouth of the creek. 

About 230 feet south of the main outcrop of manganese oxide a 

different kind of breccia forms a fault scarp 25-30 feet high. Most of 

the breccia fragments are less than 2 inches in diameter. The rock is 

too badly weathered to be definitely identified, but it appears to be 

silicic and is perhaps rhyolitic. Underneath the cliff-forming breccia, 
MANGANESE DEPOSITS-PANAMA 

200Feet 

EXPLANATION 

/- OutcropsofmanganeseOXIde. 

Lona:dasheswhereconce<Med; short dashes where in· 

forred 

Manganes.eoKideboulders 

p Strike and dip of beds 

...;!.0 

Strtkeofverticalbeds 

=v Opencut,pit,ortrench 

FIGURE 10.-Map of the Hyatt no. 2 manganese mine, Provincia de Col6n, Panama. 

125 

soft, deeply weathered breccia is exposed near the base of the scarp. 

Decomposed breccia is also exposed in a few cuts along Manganese 

Creek and in a cut near the summit of Mine Hill. Manganese oxide 

appears to occur in this breccia, although the only rock exposed in 

contact with the oxide is red and brown clay containing small fragments of rock that is possibly shale but is weathered beyond recog-
126 MINERAL DEPOSITS OF CENTRAL AMERICA 

nition. The general structure of the area is obscure; dips are predominantly eastward and southward, and the breccia appears to be overlain 

by shale, which is turn is overlain by limestone. 

The main outcrop of the south deposits is at the top of a steep hill 

300 feet above the mouth of Manganese Creek and forms a steep cliff 

15 feet high at the edge of a flat bench about 65 feet wide. The deposit, as determined by trenching and exposures in the cliff, covers an 

area of about 7,500 square feet. Most of the trenches are partly caved, 

and both the attitude and the total area of the ore body are uncertain, but the roughly circular shape of the outcrop, together with 

the bench at the top of the steep slope, suggests a flat-lying body. 

Thicknesses range from 6 feet in 2 of the trenches to 10 feet in the 

face of the cliff. According to reports shale was exposed in a cut, 

long since caved, at the base of the cliff and below the bench. 

The cliff presents the best exposures. The upper 6 feet of the cliff 

consists of red clay, which is stained in places with black manganese 

oxide and contains considerable admixed specular hematite. The 

lower 10 feet is massive soft manganese oxide overlain by a thin uneven layer of specularite, and the slope below the cliff is spangled 

with tiny flecks of bright specularite. Some of the manganese oxide 

contains streaks of red clay or a few thin veins of specularite. The 

oxide is largely dull-gray pyrolusite of very high grade, averaging 

about 50 percent manganese. Near the base of the cliff is an irregular 

mass of brownish-black partly oxidized manganiferous calcite, cut 

by veins of calcite and malachite. Only small quantities of carbonate 

were found, and it is doubtful whether this is the primary mineral of 

the entire body. All analyses known to the writer show a small percentage of copper. 

One hundred and sixty feet to the northeast, near the upper edge 

of the bench, another system of trenches outlines a small, apparently 

flat-lying, body of oxide about 1,100 square feet in area and probably 

not over 3 feet in average thickness. The oxide is soft pyrolusite 

similar to that of the main body. 

Manganese oxide deposits crop out at several places southwest of 

the main outcrop, but exploration has shown them to be very small. 

Heavy float is found along the middle fork of Manganese Creek and 

along the nose between its 2 main branches, where the largest boulder 

seen weighed about 15 tons. Many of the trenches show rounded concretionary masses of mixed manganese oxide and clay in a clay matrix. These masses are thought to be concentrations of manganese 

oxide leached from outcrops above and redeposited by surface waters. 

The concretions are 1-12 inches in diameter and are found to a depth 

of at least 10 feet. The oxide is so soft that it can easily be cut with 

a machete. It averages about 40 percent ma.nganese; clay is the principal impurity. 
MANGANESE DEPOSIT8-PANAMA 127 

The north deposits lie on the north slope of Mine Hill, at the head 

of Copper Creek, about 650 feet north-northeast of the main south 

outcrop. Deeply weathered volcanic breccia is exposed on the hill 

between the north and south deposits, and no manganese oxide was 

seen near the summit on either side. The north deposit consists of sev· 

eral small oxide bodies and numerous boulders that are exposed in 

shallow trenches on a gently sloping bench. None of the outcrops 

app6ars to be connected with any other, and exploration has failed 

to find any appreciable amount of oxide. 

Just west o:f the trail, at an altitude of 750 feet, an opencut exposes 

a body of manganese oxide 25 feet long and less than 3 feet thick 

which strikes N. 20° E. and is vertical. Eighty-five feet to the east a 

trench exposes several large boulders, and 70 feet farther on is an apparently flat-lying body about 15 feet long and 3 feet thick. About 

100 feet to the southeast 2 trenches expose a few boulders which may 

indicate the presence of a small ore body. None of these bodies appears to be connected, for trenches between them are barren. Copper 

Creek carries heavy manganese-bearing float from near its head all 

the way to the Rio Boquer6n. 

':fhe oxide is very high grade soft bluish -gray pyrolusite, similar to 

that on the south side but perhaps even richer in manganese. Near 

some of the ore bodies the surrounding clay is heavily impregnated 

with manganese oxide. It has been suggested that perhaps the south 

and north deposits are connected as a flat-lying sheet under Mine Hill. 

Although this is possible, the small areas covered by the two deposits, 

as compared with the great distance between them, makes it decidedly 

improbable. 

Little can be said about the origin of the oxide at the no. 2 mine. 

Exploration was inadequate; most of the old trenches are caved, and 

only clay is found in contact with the oxide. It is not known whether 

the primary mineral is manganese oxide. No other manganese mineral was seen, except for small quantities of what is probably manganiferous calcite. However, some boulders in Manganese Creek 

show irregular isolated patches of jasper surrounded by manganese 

oxide which has replaced the jasper; others have small clay-filled 

pockets that may represent leached jasper remnants. The oxide in 

these boulders is hard and siliceous, in contrast to the soft pure oxide 

of the main ore body. Some boulders show two generations of oxides, 

the earlier being brecciated and then cemented by the later. Much of 

the earlier oxide is more coarsely crystalline than the later. 

Although the origin of the main ore body is not definitely known, 

the writer believes that the deposit is similar to other manganese deposits in eastern Panama in that the oxide is epigenetic and has been 

deposited by ascending solutions. The p.rimary mineral may have 

been the hard psilomelane-type oxide that is commonly found in these 
128 MINERAL DEPOSITS OF CENTRAL AMERICA 

deposits, and the soft pyrolusite may have been formed by alteration 

of the earlier oxide, perhaps by surface waters that removed part of 

the oxide and redeposited it in the concretionary. masses found below 

the outcrop. The specular hematite is later than the manganese, for 

it is found along a shea.r zone and in thin veins in the main ore body, 

as well as along the upper contact of clay and oxide. The no. 2 mine 

is the only one in Panama, seen by the writer, at which specular hematite is found. The veinlets of malachite are confined to the irregular 

mass of manganiferous calcite found near the base of the main ore 

body, and both carbonates are thought to be later than the manganese 

oxide. 

CALZADA LARGA AREA 

The Calzada Larga area is in the Provincia de Panama in the low 

hills south of Calzada Larga, about 21h miles south of Madden Lake 

and 14 airline miles north of Panama. It is 25 miles from Panama 

over a road that passes through Chilibre. 

The manganese deposit lies on the south flank of a low ridge between 

the Rio Chilibrillo and a small creek. The ridge is cmnposed of deeply 

weathered agglomerate and tuff, probably andesitic, with fragment£ 

as much as 16 inches in diameter. 

A vein of manganese oxide, 1 to 16 inches thick and averaging about 

4 inches, is exposed in several pits. The vein strikes northward for 

about 40 feet from its southernmost exposure, then east-northeastward 

for 30 feet. It dips 75°· E. to 55° NW. The vein follows a fault in 

the agglomerate and cuts through boulders and matrix. In the cut at 

the bend in the vein, two small branch veins are exposed. In this cut 

the hanging wall is altered to a yellow clay for 2 inches from the 

vein. Numerous small pieces of float are found on the slope below 

the outcrop. The oxide is soft crystalline pyrolusite, some of which 

is finely banded parallel to the vein walls. No other manganese mineral was seen, and the oxide may be primary. 

About 2 tons of oxide has been taken from the vein and the pits in 

the float area below the vein. The average manganese content is about 

50 percent. Only a small amount of oxide is likely to be found here, 

as the vein has been well exposed and shown to be too narrow to 

provide much tonnage. 

BAHiA DE MONTIJO-PONUGA AREA 

The Provincia de Veraguas manganese deposits described below are 

in the vicinity of Bahia de Montijo, a large shallow indentation on 

the Pacific Ocean side of the province. The largest towns in the region 

are Santiago, 175 miles southwest of Panam'a on the Panama-Dav~d 

highway, and Sona, 30 miles west of Santiago. A surfaced road runs 

from. Santiago 8 miles southeastward to Atalaya, and from Atalaya 

a dry-weather dirt road leads to Ponuga, 15 miles south of Atalaya 
.· MANGANESE DEPOSIT8-PANAMA 129 

and 7 miles east of Bahia de Montijo. There is a fair landing field 

at Mariato, 10 miles south of Ponuga. The country between Ponuga 

and Atalaya is traversed by numerous trails, so that most of it is 

fairly accessible. The country around Bahia de Montijo is partly covered with heavy vegetation, but it includes some large areas of open 

grassland. 

HARRIET PROSPECT 

The Harriet prospect (fig. 11) , also known as the Rosario prospect, 

lies west of Bahia de Montijo, on the west side of a prominent hill 

about half a mile north of Bahia Honda. The deposit is at about lat 

7°47' N. and long 81 °31' W., 155 airline miles southwest of Panama. 

Bahia Honda is a fine natural harbor and has been charted by the 

U. S. Navy Hydrographic Office (Chart no. 1040). It is about 250 

miles by boat from Panama, 70 miles by boat from Sona by way of the 

Rio San Pablo and Bahia de Montijo, and 60 miles by boat from 

Puerto Real, which is 11 miles by road south of Santiago. A trail 

leads from Bahia Honda to Somi through country that is said to be 

difficult to traverse. The only native settlement in the vicinity is a 

small village on the north shore of Isla Talon, in the center of the bay. 

The tides at Bahia Honda, as elsewhere along the Pacific coast of 

Panan1a, are very high, ranging from 10 to 18 feet, and at low tide mud 

flats 2,000-4,000 feet wide are exposed along the north shore of the 

bay. Between the manganese deposit and the bay is a belt of mangrove 

swamp 300-2,000 feet wide. 

Prospecting was first begun in 1921, when a sizable outcrop is said 

to have been found along the bottom of a small tributary of the Rio 

Luis, which flows into the bay directly north of Isla Talon. Further 

prospecting was done about 1935, when the entire area was cleared and 

a small amount of trenching was done on two outcrops on the west 

side of Harriet Hill. No :further work has been done and no production has come from the deposit. At present the old prospect workings are completely covered by landslides and jungle. A small amount 

of material, perhaps 100 tons, has been transferred to Isla Talon for 

shipment, and a 500-pound sample of this material was taken for 

assay. This sample is said to have contained 47 percent manganese 

and 8 percent silica. There is also a good deal of ore in the foundations of some of the native houses on the island. 

The deposit consists of 2 outcrops of manganese ore, 1 on either side 

of a small saddle on the west side of a prominent hill easily risible 

from the bay. Both outcrops lie at altitudes ranging from 200 to 330 

feet and are a little more than a mile by boat and trail from _th~ bay. 

The country is blanketed by dense jungle, and the area near the outcrops, cleared in 1935, is covered by an even denser second growth of 

small trees and shrubs. Only red clay is exposed near the north out-
130 MINERAL DEPOSITS OF CENTRAL AMERICA 

EXPLANATION 

[I] . 

. Partially oxidized manganese 

silicate boulders 

Outc;rop Qf partially oxidized 

manganese silicate 

90 ---+-

Strike and dip of vertical beds 

50 0 

HARRlET HILL 

Andesite, 1 m thick 

2m thick.~~ 

: ... ·\\x90 

: ; : · ~h 3 m thick 

...... ~~. '\. 

.·.·.·.·.·.·.. "" .... 150 Feet ·:: • .... 10 0 50 Meters I I I I I I I I 

Contour interval 20 meters 

Datum is approximate sea level 

FIGURm 11.-Map of the Harriet manganese deposits, Provincia de Veraguas, Panama. 

crop, but at the south outcrop one trench exposes a deeply weathered 

andesitic volcanic rock. 

The north outcrop is on the east side of a steep canyon and consists 

of a lens of manganese oxide and silicate minerals that strikes north 

and dips vertically. The lens is exposed intermittently for 165 feet 
MANGANESE DEPOSITB-PANAMA. 131 

and ranges in thickness from 10 to 25 feet, with an average thickness 

of about 16 feet. It crops out-over a vertical-distanee-o-f-1-30-feet.. The 

canyon at the lower end and a trench at the upper.·end clearly define 

the length of the lens. The canyon wall below th~ outcrop shows numerous small boulders of or-e, as does the creeltbed for a consideraple 

distance downstream. 

The manganiferous material consists of har-d blu~-black psilomelan&· 

that encloses some unoxidized manganese silicate and;. to judge from:-

the amount of limonite present, an appreciable amount Qf iron. Theh 

manganese oxide is the result of oxidation of a vein or bQ~ of md.:h" 

ganese silicate, either neotocite or bementite. The depth of oxidation 

is unknown, but the presence of unoxidized remnants in the surffl,ce 

material indicates that oxidation at depth is probably not complete. 

The second deposit is about 500 feet farther south and;Jies approximately in th'~ line of strike of the north deposit. There are no exposures between the two deposits, which appear tp.be entirely separate 

although perhaps localized along the samJ~. bed or shear zone. The deposit is a. poorly exposed lens: of siliooous.:In~nganiferous rock about 80 

feet long and 3-10 feet wide~ It str-ikes N~.l5°·W.; its dip is uncert~in 

but probably steep. Manganese-b~aring rock .is. exposed at only three 

places along the strike, and the ore-. hody may· not, be continuous between them. On the hillside below a:re.numeroq~, boulders that h~ve 

broken from the:outcrop. _ 

The rock consists largely of siliceous manganese oxide, both massive 

and in thin veinlets in jasper, similar to the material in the na,:-th 

deposit but more siliceous. · 

Exploratory work at the Harriet depPsit has been inadequate and 

furnishes litUe information on which to base an estimate of reserves. 

Some of the ore that appears to be in place_may be only large boulders, 

and the srze of the qre body may be overestimated. Many small 

boulders occur along several stream ~ourses, and.!:tlthough several hundred tons might be picked up along the tributaries of the Rio Luis, the 

total tonnage: to be expected is small~ . : 

LA MATILDE!DEPOSITS 

The La lfl:ttilde manganese depo~its (fig. 12-) al.'~ in. a range of low 

hills about 5 miles north of Ponuga:and 10 mil~ south of Atalaya, at 

about lat 7°53' N. and long 80°54' W., 15 mile.s sout~-s.outhea~ of' 

Santiago and 120 miles southwest:of Panama .. · ·The- marin trail f~m 

Ocu to Ponuga passes along the valley south of th:e·hins, and thetraiJi 

from Ponuga to Ce:rros Altos and Atalay.a.Cl~~osses _the ridg& neax·the, 

west end of the property. The dry-weather automobile r0arl :fnpm 

Atalaya to F'onuga'lies about 2 miles to the west. The Sl!lllTounding 

region is a dt~ply dissect-ed· terrain of law-steep-sided-hills-ttn:lf many 

small canyons. 
o· t--~'/ o/ 

A..'~-/__ .. 

~t?J/-t-T' ,/. ..l...J/{'J 

.·.·· ... ~ 

./=~~::~.;, ... /~o•o, /· .~~ ij·~· ..... ::·.~~· ;.:. , ,., . '""":'•'.'""'" . • ... .,. .. --=-t.· • • • :;t,· :VJ .a s p e··· r .. •. ·:. · J Red shale · 

f.·o::o ... ;-=::;··"··· • ----- Shale • • \ 

. l 30 ~ • I . Vole ----- .-. ·.~ : --L.. Jasper 

; / ~ anle rock;--?_.·~~.. ! /.: : ~~t.'-": . ....... ~ : .. : ... . . I '\ • >·-· . I I . . . . . o•,~: ·:: 0 • 0 • • • • • 

c,Vj: 80 o ........ ' ,-1?.:'' •. 

) ', 70 / T•ff •'. 

·.···· 

/ ... _ .,>-::/ ,/' ---~o , ........ Tuff 

~' T~ff,, 

f / \ • ·':-:-;,·_ • : L ·::·:·:·.:·.:-::::~·::::. ·::::: :.. :.': ! / _ ·l:-.:t_ ~ >:: .. :.:.:.: .... ·~~~]~e~~s.?~l~~ 

___ j_L_:::-::_____ _ _ TRAIL ............ , .. • ;·;:~·;;{:~:;:·.:J/1 :::· .. ·::::.:.~·~· - PONIJGA , 8 KM ---------------------- .... ---------~·;;.=-·f..-1 "'o•:• o • •.: o : • • • o • -_;,..~;; . ·. 

EJill . 

. Boulders of siliceous 1 

manganese oxide 

-. 

500 0 1000 Feet 

I I I I I I I ., 

EXPLANATION 

... ---?-----?-----

, Inferred contact 

40 --L.. 

Strike and dip of beds 

II I I I.;. l 

.Opencut, pit, or trench 

FIGURE 12.-Map of the La Matilde manganese deposits, Provincia de Veraguas, Panama. 

....... 

~ 

1:-.j 

e 

~ 

~ 1:1 

l:'j 

~ ::3 

1/). 

0 

1::.1 

c 

l:'j 

~ 

~ 

~ 

~ 
MANGANESE DEPOSITS-PANAMA 133 

The deposits have been explored from time to time since 1920 or 

1921; the main development work is thought to have been done in 1921 

and 1935. Although the area has been cleared at least once, much of it 

in 1942 was covered with a thick mantle of second growth, denser than 

the virgin jungle. No record was found of any commercial production 

from the property. 

The La Matilde deposits occupy three low hills (fig. 12) ; the west 

and middle hills are separated by a broad valley, and the middle and 

east hills are separated by Quebrada Las Lajas. The manganese ore 

occurs in a thick belt of shale or mudstone and clay, probably of Oligo~ 

cene age, that dips about 30° N. and overlies a series of volcanic rocks, 

which are we~n exposed along the trail at the base of the hills. The 

volcanic rocks include rhyolitic ash and tuff and andesitic and basaltic 

agglomerates. All these rocks are so deeply weathered that reliable 

petrographic determinations cannot be made in the field. 

The north and west sides of West Hill are covered with boulders 

and nodules of manganese oxide over an area of roughiy 5 acres. This 

float ore is further exposed in several trenches, and a thin bed ·of 

mAnganiferous jasper, striking northwestward and dipping 40° NE., 

shows in the westernmost trench. Near the east end of the float area 

is a trench in a thin mantle of high-grade manganese oxide nodules 

resting on clay and jasper. The layer of manganese-bearing rock is 

only about 10 inches thick, and not more than 25 percent of it consists 

of oxide. The oxide is heavy material of the psilomelane type and 

appears to hE~ distributed over an area roughly 165 feet in diameter. 

The remainder of the float and the material exposed in the trenches 

to the west eonsist largely of jasper and shale cut by thin veins of 

manganese oxide. Many other small bodies of manganese oxide Wf're 

apparently formed by replacement of brecciated jasper. No estimate 

of the tonnage in the area has been made, since very little exploratory 

work has been done; the average manganiferous material appears to 

contain less than 20 percent manganese. 

Near the base of the hill, about 500 feet southeast of the float area 

described above, is another heavy concentration of boulders of manganiferous rock, jasper, and dark chert, in an area that, like the other, is 

about 165 feet in diameter. About 1 boulder in 4 is manganiferous and 

consists largely of reddish-black manganese silicate. The boulders 

contain small pockets of soft gray pyrolusite in groups of radiating 

prismatic crystals, but not more than 5 percent of any specimen examined was manganese oxide. .A .. few pieces of jasper occur alongthe 

base of the hill between the float area and the broad valley that separates the west and middle hills. No manganiferous boulders were seen 

there or in the valley itself . 

. The largest concentration of manganese ore on the La Matilde property is on the gentle slope near the base of Middle Hill, where ·a north-
134 MINERAL DEPOSITS OF CENTRAL AMERICA 

ward -trending trench 200 feet long has been cut in a mantle of boulders 

of manganse oxide and jasper. At the south end and near the middle 

of the trench are heavy concentrations of boulders, suggesting the p~­

sible presence of ore bodies nearby. The north end of the trench exposes a bed 23 feet thick which can be traced for 165 feet to the west. 

Some of this bed is heavy bluish oxide of the psil.omelane type, but 

the predominap.t rock is a deeply weathered-jasper cut by many veins 

of manganese oxide and coated along fractures with films of manganese 

oxide. The float cov~rs an area about 650 feet loJ:!g by 250 feet wide 

and probably extends .to. a depth of at least 3 feet. 

. Beyond the north end. of the trench the slope of the ~~IJ steepens 

abruptly. Another trench, 160 feet up the slope, exposes a sim,ilar 

mantle of boulders nearly 2 feet thick . .About a quarter of the bouid-

, ers, some of which weigh more than a ton, are composed of manganese 

oxide. Although it is possible that an ore body may be near the upper 

end of the trench, no rock was seen that was known to be in place .. · As 

the ground around the trench was covered with a dense blanket of 

fallen timber at the ti~e of examination, the total area of float could 

n()t be d.etermined, but float is probably present to a depth of 2 feet~in 

an area 165 feet long and 80 feet wide. · 

A.16-foot-deep pit.130 feet no:rthwest of the second trench exposes 

bright: red shale that strikes eastward and dips 30° N. The shale contains·many small interbedded lenses of jasper but no manganese ore. 

Fi$teen ~eet east of the pit a shal,low trench 200 feet long cuts across a 

bed of j'asper 6 feet thick which strikes eastward and appears·to dip 

northward. This bed can be traced westward to a point just a~ove the 

pit, where its continuation, if one ~xists, is ·bur~ed. The wall rock is 

r~. ~hale similar to tha;t in the pit. The jasper contains a good deal of 

ll;qn. and very little manganese .. 

· , · On 'the wes.t· slope of East Hill, between" the trail to Ocu, and 

Quebrada LasLajas, a few boulde;rs of nearly pure manganese oxide 

were seen; this area is entirely unprospected, and the source of ,the 

boulders has not been found. The ore was of higher gr~de than that 

8een anywhere else on the La Matilda property,. but the amount ~f 

manganese oxide was very small. 

NUESTRO AMO PROSPECT 

The Nuestro Amo deposit is at the top of a low ridge nearly 2 miles 

west of the small village of Nuestro Amo, which is 2lh miles south of 

Atalaya and can be reached by automobile during the dry season. The 

trail from the village to the deposit passes over fairly level country 

that offers no serious obstacle to roadbuilding. 

This property was prospected in 1928 at the· same time as the La 

Matilde deposits to the south, but the writer saw no evidence of any 

former work. It is said that a pit 16 feet deep was in good manganese 
MANGANESE DEPOSIT&.-HONDURAS 135 

o~de for its full depth; if so, the pit is now completely filled and 

even its location is uncertain. There has been no production from 

the deposit. . 

Along the trail from the ·village to· the deposit· are· exposures of 

andesitic and basaltic tuff and agglomerate and many residual b{ml~ 

ders of weathered agglomerate. ln the vicinity of the deposit, 

amygdaloidal andesite is exposed in a trench, and andesite tuff crops 

out near a smaJlcanyon on the south edge of the property . 

. Manganese-bea:r;ing rock was seen.at two places on the property .. A 

trench 65 fe~t. long exposes ~ lenticular body 10 feet long and with, a 

maximum thickness of about 11h feet which strikes north and dips 35<> 

E~_. The walls are deeply weathered porphyr~tic a:p1ygdaloidal vol· 

canic rock, probably andesitic; the amygdules · consist of calcite: or 

greenish opal. A _few small pieces of float ore were found in the a~ 

between the trench and the trail to the north. 

The lens is. de~p-red to reddish-black manganese\ silicate, which has 

bee~ superficially altered to a heavy bluish oxide of the psilomelane 

type enclosing sm.all pockets of soft, powdery black oxide. .The oxide 

i~. ~f high gr::tde, containing more than 50 percent .manganese, l;mt the 

af!lount in. sight is very small. Some high -gr;tde float occ~r,s in the 

canyon on the south .edge of the property, but here also. the quantity 

1s small. · . · .·. 

HONDURAS 

Although many manganese deposits are known in Honduras, no ore 

has been shipped from them. In 1942 several of them were explored, 

but none appeared likely to be workable at a 'profit, even under th~ 

stimulus of high prices. The deposits examined are in upper Tertiary 

lavas~and pyroclastic and sedimentaryrocks which· cover much of central and southern Honduras (pl. 1). These rocks ·commonly strike 

eastward,. dip gently southward, and are locally Iolded into broad 

anticlines and synclines. Faults were seen in several places, hp.t none 

appeared to be of large displacement. 

The manganese of the ore bodies appears to o~cur entirely as oxides, 

chiefly pyrolusite and psilomelane. Chalcedony is a constituent of 

most of the ore bodies, and some of it is intimately mixed with· the 

manganese oxid-es. The iron content of the ore appears to be low. 

The ore bodies may be classified into flat or 1 gently dipping bodies 

parallel to the bedding, and steeply dipping veins that follow fauits 

or fractures. The veins are commonly sniall or lean; they are not 

persistent ·and none of· them discovered up to _1941 is likely ·to yield 

ore bodies of commercial size and grade. The flat or gently dipping 

ore bodies have not shown great promise, although some of them may 

prove to be worth mining. The Tendal ore body in the La Mesilla 

area is at least 140 feet long and from 6 inches to 3% feet thick and 

388364--57----10 
136 MINERAL DEPOSITS OF CENTRAL AMERICA 

has been explored down the dip for nearly 50 feet. The ore· as mined 

probably does not contain more than 30 percent manganese, but a 

product of shipping grade can be obtained by sorting. . The other 

deposits had not been explored sufficiently to permit estimates as to 

tonnage and grade. LA MESILLA AREA 

Tile La Mesilla-area is 18 miles:east:·of Pespi~e~ Depia~t~rir~rito'de 

Choluteca. In 1941 it was under option to Dr. Dhiz Pardo of Havana, 

Cuba. Manganese deposits have been discovered over a wide area,·but 

those that have been explored-the Tendal, Ruben, Malachate, and 

Cerro Bonito-are all near the top of the La Mesilla mesa. The road 

from Pespire to Tamarindo, 9 miles distant, is suited for oxcarts with 

light loads and could be improved at sniall expense for truck traffic. 

The 9-mile section from Tamarindo to La Mesilla, however, is steep 

~:. ro~J~)\ and ca.considerable,exp~ri.dWure wouid bei n~essa-~y. to ra~~·. 

it passable for trucks. 

Hardly enough ore has been mined in this area to give an idea of 

mining costs under operating conditions, but in 1942 the average cost 

of mining and sorting was about $8 a long ton. The cost may become 

less.as local labor becomes more· effi.~~np, hut~ap~, ~~iQn. .. f.or•this 

reason will: be offset~ to some: extehe by . increased 'ci>sts, as' mining . 

progresses down the dip. The estimated cost of transporting a long 

ton to Amapala, the nearest port, was about $14. 

TENDAL MINE 

The Tendal ore body (fig. 13) is the largest discovered in the La 

Mesilla area up to 1941. The ore follows bedding in tuffs that strike 

east ~:n~ 4i~ 2.0~.~· ~ It.i9q~~.o~-.:~,a~,apd.py.ro~n~~~\;~~·~~~~~h cha~dony~·'and it replaces a tliirl bed oftnff. , ,, . ... . . . 

The ore body has been traced along the strike for 250 feet and has 

been explored for 140 feet to a maximum depth of 50 feet down the 

dip. Its thickness ranges from 6 inches to as much as 3% feet. On 

the west side of the open pit the ore layer averages 2 feet in thickness 

and consists largely of black chalcedony, partly replaced by irregular 

veins, pockets,. and layers of pyrolusite. A thin layer of oxide is commonly found at the base and top of the chalcedony bed, and manganese o~ides locally replace the tuff above and below the chalcedony. 

On the east side of the open pit the ore bed is 2-3% feet thick and is 

of good grade, consisting of nearly equal parts of black chalcedony 

and manganese oxide. At one place the bed contains a little limonite, 

but for the most part the iron content appears to be low. 

In 1941 a shaft was being sunk 250 feet south of the main pit to 

explore the ore zone at depth. The· shaft was then 24 feet deep and 

was expected to penetrate the ore at a depth of 90 feet. The outcrop 

of the zone west of the main pit shows only low-grade siliceous float. 
·MANGANESE DEPOSITB-HONDURAS 137 

EXPLANATION 

Q 

. L,,,,., .. ,,,.,,,,i Manpneseote 

~-~m.;t;iy·~: dotted where concealed 

=-:;~~~ 

-.,?5 

Stnkeanddipofbeds 

_ ... _,.,. ...... J. 1943 

FIOOBJD 13.-Map of the Tendal workings. La Mesilla area, Departamento de 

Choluteca, Honduras. 

It is impossible to predict the grade of the material that may be found 

at depth. 

The manganese content of the ore. mined ranges from 10 to 50 percent. and :.probably) dues •nQt · a veraf$enho:VE~h than::3o iper-Cen·tr ~ The ore 

was being hand sorted.to the grades shown in the assays below. 

Assays of mang.auese .. or.e f:ro,m the Tendal mine,. Hondur..as 

Silica and in· 

Sample No. Mn (percent) Fe {percent) soluble residue Remarks 

(percent) 

Mn2 _______ 22.87 2.24 52.44 Siliceous ore, rejected. Mn3 _______ 42.62 1. 42 25. 16 Dense oxides, selected for shipment. Mn4 __ ;. ____ 42.01 2.73 17. 54 Wad. Mn5 _______ 34.63 1. 05 33.68 Porous and dense ore, selected 

for shipmellt. 

~-~····-· 

QUEBRADA DE RUBEN PROSPJiCT 

At Quebrada de Ruben, about half a, mile south of Tendal, a small 

pit in tuff shows an ore body of soft wad about 5 feet wide that strikes 

N. 20°-40° E., dips steeply nor.thwestward, and appears to follow ·a 
138 MINEBAL DEPOSITS OF CENTRAL ;.AMERICA 

fault. A sample of sorted ore was analyzed with the following results: 52.55 percent manganese, 0.47 percent iron, and 4.76 percent 

silica and other insoluble material. A large tonnage is not likely to 

be found, for bedrock is well exposed so nearby along the strike that 

the ore body may be less than 50 feet long. 

MALACHATE PROSPECT 

Workings in the Malachate prospect, about 500 feet northeast of 

Quebrada de Ruben, explore a lens of manganese oxide and chalce-· 

dony that is parallel to the bedding of the enclosing tuff, which strikes 

north and dips 30° W. The lens is about 50 feet long and at least 6 

feet thick and has been uncovered down the dip for 10 feet. 

The chalcedony is gray or black because of finely disseminated manganese oxides, which also form small veins and iiTegular pockets and 

locally replace the tuff adjacent to the chalcedony. As the ore is of 

low grade because of its high silica content, and as it contains only a 

small tonnage, the deposit is p.robably not of commercial importance •. 

CERRO BONITO PROSPECT 

The Cerro Bonito prospect is a third of a mile southwest of the Ten-· 

dal deposit. The workings explore small discontinuous manganese· 

oxide veins in tuff, ranging in width from a fraction of an inch to 6· 

inches. As the ore is of low grade and the available tonnage is small,.. 

the deposit has no commercial value. . ·; ,_ 

'S.4.B.4.N.4.GR.4.fvDE AREA 

Several prospects have- been opened up near the 61-kilometer ·post 

on the San Lorenzo highway south of Tegucigalpa, and 2. of them 

were examined .. One, 300 feet west- of the highway, shows veins of 

manganese oxide as mucli as 6 inches wide in rhyol~te. The veins are· 

lenticular, and although some of the ore is nearly pure pyrolusite,.. 

most of it is so low in grade that the prospect does not appear to have· 

any commercial possibilities. At the other prospect, which is about· 

2 miles west of the highway, manganese oxides are irregularly distributed throughout tuff. The material is low grade and only a few tons: 

appear to be available. · 

YILLA NUEY A. ARE4 

Near Villa Nue"tra, a village about 6 miles southwest of Tegucigalpa,. 

Robert Hickish has denounced 2 manganese deposits. In 1 of them,. 

500 feet west of Villa Nueva, a fault zone in conglomerate trends N. 

70° W. and dips northeastward, and the fractured rock in the zone is 

locally stained by low-grade manganese and iron oxides. In the other, 

about 1,000 feet northeast of ·Villa Nueva, manganese oxide is sparsely 

distributed in conglomerate, but the grade and tonnage are so low that:. 

the deposit has no commerGial value. · 
~GANESE DEPOSIT&--HONDUBAS 139 

FLOR AZUL PROSPECT 

The Flor Azul prospect, owned by Robert Hickish, of Tegucigalpa, 

is, about 6 miles north of Moroceli. The property was under option to 

Dr. Diaz Pardo, of Havana, Cuba, in 1941. 

Four shallow cuts explore a fractured zone ·containing manganese 

roxide veins and pockets. The zone crops out for 260 feet along the 

'Strike and in its· widest part is as much as 90 feet wide. Thepockets 

and veins of manganese oxides commonly contain fragments of rhyolite and unreplaced crystals of quartz and feldspar. A. sample of the 

ore was assayed by the Geological Survey with the.following results: 

19.75 percent manganese, 2.35 percent iron, and 58.90 percent silica 

:and insoluble residue. In soine places the ore may be of higher grade, 

but in others it appears to be leaner; moreov-er, below the surface, the 

percentage of oxide minerals is likely to decrease. 

OJOJONA DEPOSITS 11 

Manganese deposits occur 9 miles south of Ojojona, onthe Finca 

Valladares. A road passable during the dry season extends from the 

Tegucigalpa-San Lorenzo highway to Ojojona, but travel southward 

to the ranch is possible only over a. rough trail. 

The rocks in. the area. are interbedded. porphyritic andesite .and :ash 

•beds of Tertiary age that dip southward at low angles. These rocks 

have been gently folded and have been broken by faults that trend 

northwestward and northeastward. The manganese ore consists, of 

pyrolusite and other manganese oxides, generally mixed with much 

waste rock; it is· assoeiated with veins that contain copper, gold, lead, 

:and silver. At the Amatillo no. 5 and the Pozo no. 2 workings the man-

·ganese ore bodies appear to be thin, surficial deposits· formed by me-

·Chanical and chemical concentration from older deposits, possibly 

veins. 

The Amatillo nos. 1, 2, 3, and 4 workings are about 21h miles south 

·Of the Finca Valladares house. Several adits and shafts explore copper ore on northeastward-trending fractures. In a mineralized zone 

about 600 feet long the fractures are locally stained with manganese 

-oxides, but the material is low grade. The Amatillo no. 5 workings are 

-on the crest of the ridge about 400 feet northeast of the no. 4 workings. 

The manganese ore is exposed over an area about 600 feet long by 150 

feet wide. Although no exploratory work has been done to determine 

the depth to which the material extends, the deposit is thought to be 

shallow. A sample of picked ore yielded 24.39 percent manganese and 

3.1 ounces of silver to the ton. 

• Hyde, P. W., Report to the New York and Honduras Rosario Mining Co., Honduras. 
140 MINERAL DEPOSITS OF CENTRAL AMERICA 

The Pozo workings, about 21h miles southwest of the Finca Valiadares house, consist of several adits, which were caved in 1941, and a 

shaft, that explore silver-lead shows along northwestward-trending 

fracture zones. At the Pozo no. 2 workings manganese ore is exposed 

as a cap, about 500 feet long by 150 feet wide, on the side of the ridge:. 

A picked sample of the material contained 25.43 percent manganes6' 

and 0.92 ounce of silver to the ton. 

The Amatillo and Pozo manganese deposits are fairly extensive·, but 

the grade of the ore on the whole is low, as even picked samples are· toolean to make ore suitable for shipping. The tonnage available is not_ 

great enough to warrant installing a concentrator. 

EL APINTAL PROSPECT 

The El Apintal manganese prospect is. 21h miles northeast of 

Pespire, Departamento de Choluteca, on tl}e ranch of Marcial Ramos~ 

Two shallow cuts show that the ore extends to a depth of only 6 feet 

below the surface. The ore, soft wad, occurs in veinlets 1-2 inches 

wide in fractured andesite, which is intercalated with volcanic tuff and 

breccia. 

OTHER DEPOSITS 

Other deposits were called to the writers' attention, but because 

sufficient time was not available they were not examined. Specimens 

offered were for the most part wad and psilomelane, similar in general 

appearance to specimens collected at the deposits already mentioned,. 

and descriptions of the properties suggested that for the most part 

tonnages were small. In addition, most of these deposits are so far 

from highways and from the seacoast that transportation costs would 

make it unprofitable to mine them at present prices. 

The following properties, none of which have been developed, were 

reported: 

Juan Avila Ruiz, Tegucigalpa; near Sabanagrande, DepartamentO> 

de Tegucigalpa. 

Ojojona,.Departamento de Tegueigalpa. Deposit llh miles SQuth 

of Ojojona on trail to Reitoca. Owner not known. 

El Apintal, northeast of Pespire, Departamento de Choluteca .. 

Owner not known. 

Federico Kohn, San Lorenzo, Departamento de Valle. 

Ruben Pineda P ., Intibuca, Departamento de Intibuca. 

Salvador Lopez, San Pedro Sula; near Siguatepeque, Departamento. 

de Gracias. 

Manganese is also reported near Gracias, Departamento de Gracias~ 
MANGANESE DEPOSlrS 141 

GUATEMALA 

PEREZ PROSPECT 

The Perez manganese prospect, Departamento de Chiquimula, is 5 

miles east of Chiquimula on the ranch of Anacleto Perez, at an altitude of 1,600 :feet. The deposit is exposed in a shallow pit along a 

sheared contact between limestone and phyllite that strikes N. 20° W. 

and dips 60° SW. The shear zone has a width of 6 :feet and contains 

lenses of soft ma:Q.gaJ;lese oxides that are .estima~d to make up about 

• 30 percent of the zone. The ore can be traced along the strike for a 

distance of about 50 :feet; it pinches out at both ends. 

A picked sample of the manganese oxides assayed 29.7 percent 

manganese, 2.76 percent cobalt, 2.94 percent nickel, and 2.3 percent 

copper. Although the content of nickel and cobalt is notably high, 

the tonnage available appears to be small. 

BRENES PROSPECT 

The Brenes prospect is about 700 feet southeast of the Perez prospect, at an altitude of 1,750 feet. The manganese here also is at the 

contact of limestone and phyllite. The manganiferous material is 

mostly soft, brown, and earthy, but locally contains darker brown and 

black nodules. It covers an area about 50 feet long by as much as 25 

:feet wide; it has not been explored in depth. Presumably the ore was 

formed by weathering of manganiferous material in the limestone, 

and it may have been concentrated by solutions migrating downward 

along the contact of the limestone and the phyllite. Nodules of the 

best material assayed 11.2 percent manganese, 0.84 percent c nickel, 

and 0.22 percent cobalt. 

LA CUMBRE DEPOSITS 

The La Cumbre deposits are a mile east of Rosario, Departamento 

de Zacapa, at an altitude of about 2,000 feet (P. W. Guild, 1943, unpublished report). The deposits can be reached by trail from Rosario. 

The ·nearest. shippi:p.g point .is. Cabaiias, a station on the International 

Railroad, 6 miles north of Rosario. 

The rocks in the area are quartz and mica schists intruded by 

diorite. The schist is cut by four veins composed chiefly o:f rhodonite; 

quartz veins locally cut the rhodonite, which in places is intergrown 

with quartz. The rhodonite veins trend northwestward and dip 

steeply; they are nearly parallel and are spaced at intervals of about 

a thousand feet. Two of the veins are about 12 feet wide and can be 

· traced for a distance of several hundred feet along the strike; anot~er 

is 18 feet or more in width and several hundred feet long. The fourth 

vein is poorly exposed and its dimensions could not be obtained.' . 

Near the surface the rhodonite is altered to manganese oxides. The 

ex:tent bf oxidatic:m is variable; in some places the surface material is 

all oxide and in others it is all rhodonite. Possibly the oxidized ore 
142 MINERAL DEPOSITS OF CENTRAL AMERICA 

.could be sorted to give a product of fair grade, but hand cobbing 

would be necessary to remove quartz and rhodonite. 

MICA DEPOSITS 

GUATEMALA 

Muscovite deposits occur in the Departamento de El Quiche and 

Departamento de Baja Verapaz in a belt 16 miles long by 3 miles wide 

that extends from El Chol, Baja Vera paz, nearly to J oyaba.j, El Quiche 

(pl. 13) (L. G. Houk, 1943, unpublished report) . The principal productive deposits are in the Agua Caliente district in the eastern part • 

<Of the belt and in the Pachalum district in the western part. Mica 

is known to occur outside these areas, but none has been exploited. 

The mica deposits are on the southern flank of the Sierra de Chuacus; 

an eastward-trending range whose highest summit, Cerro de Tuncaj, 

has an altitude of more than 8,000 feet. The region is drained by 

tributaries of the Rfo Motagua, which at Concua is about 2,200 feet 

:above sea level. ' 

The area can be reached by roads to Joyabaj and El Chol that are 

:passable the year round, but on the steep trails within.the area. travel 

is on foot or horseback. Freight from within the area is largely carried by pack animals to the roads and then by truck to railroad points. 

The mica deposits of Guatemala were known prior to 1900 but were 

first explored in 1919 by Manuel Bergua and Leon Campanolle, who 

opened the Palibatz no. 2 mine. In 1922 the Palibatz no. ·1 deposit 

was discovered, and since then it has produced continuously. The 

early production has not been recorded, but Manuel·Bergua reports 

that it was high and that up to 1926 it may have ex~eded 100,000 

pounds of sheet mica. 

Recorded production of sheet mica in Guatemala, 1928-421 

Year 

1926 ________________________ _ 

1927 ________________________ _ 

1928-------------------------

1929 ________________________ _ 1930 ________________________ _ 1931 ________________________ _ 

1932-38 _____________________ _ 1939 ________________________ _ 1940-41 _____________________ _ 1942 ________________________ _ 

TotaL _______________ ---

Value (dollars) and country where sold 

Weight (lbs) I------:------:----

24, 719 

2, 672 

11,029 

3,867 

26,598 

2,302 

23,265 

0 

1, 014 

467 

0 

3,854 

0 

6,204 

105,991 

United States Germany France 

9, 750. 00 ---------- -------- ------------ . 1, 054. QO __ _._ ____ _ 

6, 038. 08 ---------- -------- ------------ 2, 211. 54 -------- 14, 687. 68 ---------- -------- ------------ 1, 271. 20 -------- 12, 846. 96 ---------- --------

------------ 200. 00 -------- ------------ ---------- 92. 00 

540. 00 - - - - - - - - - - - - - - - - --

1, 285.00 

45,367.72 4, 736. 7 4 92. 00 

.a Figures oompiled by L. R Honk from United 'States'eon$ul8r records. 
MICA DEPOSITs-GUATEMALA 143 

GEOLOGY 

The mica deposits are in pegmatite bodies that cut gneiss, sc~ist, 

and granite. These rocks are part of a belt ranging in width from a 

few miles to 36 miles that extends across central Guatemala from 

Puerto Barrios on the Atlantic coast westward into Mexico. On the 

south this belt is overlapped by Tertiary and Quaternary lavas ,and 

pyroclastic rocks, whereas on the north it is in fault contact with sedimentary rocks of PerV!ian ( ? ) and Permian age. Serpentine masses 

whose long axes are roughly parallel to the belt intrude the schist. 

Garnet-mica schist and gneiss form the bedrock of most of theregion. These rocks are interbedded with smaller quantities of hornblende schist . and gneiss, andalusite schist, and other metamorphic 

rocks, all of which generally trend westward to northwestward ~nd 

dip steeply southward to southwestward, although locally they have 

been folded into northward-trending minor folds. 

In .the Palibatz area the metamorphic rocks are predominantly mica 

schist and gneiss, but layers of feldspathic gneiss and hornblende 

gneiss, most less than a hundred feet thick, are locally prominent. 

I4mestone, now coarsely crystallized, is intercalated with the schist 

and gneiss along the Rio Caquil west of Palibatz. The thickness of 

the limestone unit varies widely but appears to average between 100 

and 200 feet. The limestone interfingers with mica .schist .on .. both; 

sides of its -outcrop. Locally the coarsely crystalline limestone con;. 

tains small crystals of phlogopite and ·muscovite. The age of these 

rocks is not known. Sapper (1937, p. 22--23) considered them to -be 

p:re-Cambrian but-suggested that in part they may be,of early Paleozoic 

age. On plate 1 they are included in the :unit of pre-Cambrian rocks. 

South of Pachalfun and San Jose Saltan the schist and gneiss are in 

fault contact with serpentine, which extends southward to the Rio 

Motagua. The serpentine is mostly sheared and slickensided, and 

locally it contains roof pendants of limestone and shale belonging to 

the Santa Rosa and Permian limestone, which crop out widely iu 

nort~-central GYatemala. 

Granitic rocks form the core of the mountain range north of the 

mica districts. The granite intrudes the metamorphic rocks, and near 

its border the schist is recrystallized to coarse-grained gneiss. 

N umel'"OUs pegmatite dikes are associated with the granitic rocks. A 

few of the pegmatites are composed only of quartz and feldspar, but 

most of them contain mica as well. The pegmatites range from thin 

veinlets to bodies 100 feet or more in width, and some of them can be 

traced for hundreds of feet along the strike. 

The pegmatites of the Agua Caliente district are irregular i:n shape 

and generally cut across the foliation of the enclosing· rocks, although 
144 MINERAL DEPOSITS OF CENTRAL AMERICA 

some tongues and projections extend from the pegmatites along the 

foliation. The pegmatites of the Pachalum district, on the other hand, 

a.re for the most part parallel to the foliation of the schist, although 

locally they cut the foliation. Most of them are lenticular or tabular 

in shape. 

The pegmatites are composed chiefly of feldspar and quartz with 

varying proportions of other constituents. Muscovite is commonly the 

most abundant minor constituent and may make up 15 percent or more 

of the pegmatite, but g~nerally it does not,_a ver,ag~ more than 4 percent. 

Biotite, although a prominent constituent of the enclosing ·schists, has 

not been seen in the pegmatites. 

Feldspar is the chief constituent of the pegmatites; the most abundant kind is a white or pink potash feldspar-probably orthoclase, 

although plagioclase is present locally. The feldspar is commonly 

mixed with coarsely crystallized quartz, and only locally is it nearly 

pure or in a fine graphic intergrowth with quartz. In the Talaxooc 

pegmatite the feldspar is euhedral against the quartz, although in 

other places both m.inerals are commonly anhedral. In most mines the 

mica is ·enclosed in fresh feldspar·; i:ri. places, ho~ever, ·the feldspar 

has been altered to a clay mineral and the mica is soft. 

The quartz associated with the pegmatites is of two generations. 

The early quartz occurs in irregular masses, veins, or lenses, and i& 

also intergrown with feldspar. Generally the quartz occupies the 

middle part of a pegmatite body, and because it is resistant to weathering it makes bold, rugged outcrops. This quartz is fine to medium 

grained and milky. At the Zeabaj, Palibatz, and Cipres mines the 

mica occurs partly in the quartz core, and the two minerals appear 

to have crystallized contemporaneously. 

·The later quartz occurs in veinlets which cut the early quartz, the 

orthoclase, and the mica. This late quartz everywhere fills fractures. 

that. formed later than the mica. Locally the quartz was deposited in 

layers· ·as much as a quarter of· an inch· thick between ·the sheets of 

mica. It is commonly fine grained and some resembles chalcedony. 

Epidote is an accessory in some of the pegmatites. Wedge-shaped 

crystals 4-6 feet long are abundant in the Constancia mine, and large 

crystals are found also in the Palibatz no. 2 mine. The crystals commonly have their long axes normal to the contact. 

Most of the pegmatites mapped in the Agua . Caliente and Pacha.:.: 

lum districts are zoned. The zoning is best developed in the larger 

pegmatites but is generally shown to some extent even in the smaller 

bodies. Commonly the zoning consists of, a central core of milky 

quartz which is surrounded by an outer zone of feldspar and quartz. 

The feldspar and quartz in the outer zone are generally intergrown; 

in places this zone can be subdivided into an inner zone of plagioclase 
MICA DEPOSITs-GUATEMALA 145 

:and quartz and an outer zone of graphic granite or orthoclase-quartz 

intergrowth. Zoning is well shown in the Palibatz no. 1 pit (pl. 14). 

Many of the pegmatites in Guatemala contain mica crystals intergrown with the quartz and feldspar. The mica commonly makes up 

less than 15 percent of the rock, and it averages between 4 and 10 peroont. The books range from a fraction of an inch to 5 feet in diam-

-eter and average between 6 and 12 inches. Green mica generally forms 

larger books than rum and ruby mica. 

Some of the mica is disseminated throughout the pegmatite, while 

·some is concentrated in shoots that can be divided into two principal 

types: ore shoots on the hanging wall or footwall of the pegmatites 

:and ore shoots adjacent to or within quartz masses in the pegmatite. 

Most of the best and largest mica crystals are found along the bor-

·ders of the pegmatites or along and partly within quartz veins th8Jt 

:are closely associated with the pegmatites. The muscovite may be 

green, brownish green, ruby, rum, amber, or clear. Colors ranging 

from light clear green to dark brownish green are the most common 

:and grade .. intQ eaoh.- other~, Ruby, aJ,D.bet, and rum mica commonly 

occur in feldspar pegmatites that are not associated with massive 

-quartz veins or that do not contain quartz masses or lenses, as for example in the Liberated, Anono no. 1, and Talaxc6c deposits. 

Although the color of the mica found at any one mine is likely to 

be nearly uniform, it may show variations. Some pegmatites contain mica of two colors and others contain crystals that show zonal 

growth. At the Anono mine, one crystal of rum mica was noted which 

had an outer zone of green mica. At the Palibatz no. 1 mine, the mica 

in the quartz core is lighter green than that in the enclosing quartzfeldspar pegmatite. In the pit below the Palibatz no. 1 mine, the 

mica, presumably in the same pegmatite, is zoned; it shows an inner 

light-green zone surrounded by an outer zone that is dark brownish 

green. Mica., from the cont-act zone, of this pegm~tite is browmsh. 

green and forms crystals as much as 4 inches in diameter. At the 

Nueva Wellington mine the mica in a quartz lens near the pit is lighter 

green than that from the pegmatite in the pit. 

PROPERTIES OF GUATEMALAN MUSCOVITE 

Guatemalan muscovite has been marketed chiefly in the United 

States. Although formerly some of it was cut into washers and similar forms, the bulk of the material has been sold as sheet mica of vari-

·oussizes. 

The properties of mica have been well described by Sterrett (1923), 

Wierum (1938), Kesler and Olson (1942), and others, and only factors 

particularly affecting the value of Guatemalan mica are emphasized 

here. The properties of selected samples are tabulated in the following table. 
Properties of certain Guatemalan micas 1 

[Symbols: F, fair; G, good; M, medium; P, poor; S, soft; H, hard] 

Mine Quality 

Tzitzfl _______ -- ____ ----- Stained A----------- Do. ______ -------- __ Good stained ________ 

Do. ______ ---------- Stained B.---------- Chac6n ____ -- ___________ Stained A----------- Pa6j __________ ---------- Stained B.----·-----

Do. ______ ---------- Good stained. _______ Do. ______ ---------- Redstatned _________ 

Do. ___ ------------- Good stained ________ El Cipr6sno. L _________ ___ •• do _______________ 

Do.---------------- _____ do _______________ 

El Cipresno. 2---------- _____ do _______ -------- Do. ______ ~--------- Stained A.----------

ElAnonono. L _________ Stained B ___________ 

Do.---------------- Good stained. __ -____ 

Palibatz no. L--------- _____ do _______ --------

Do_---------------- Red stained _________ 

Palibatz no. 2----------- Good stained ________ 

Do.-------------- __ Stained A---------~-

Do.---------------- Stained B ___________ Bergua no. L ___________ Stained A ___________ 

Do ______ ----------- Good stained ________ 

El P6i'ez no. L--------- _____ do _______________ 

Los Volcancillos ________ Stained B. __________ 

Do. __ -------------- Good stained ________ Santa Rosa _____________ Stained B. __________ EI Jocote _______________ Good stained-------- Las Guayabas __________ -~· •.. do ______ .------ __ 

Hardness 

H 

H 

H 

s 

M 

M 

M 

M 

M 

s 

M 

M 

H 

H 

s 

s 

M 

M 

M 

H 

H 

H 

M 

M 

F 

H 

H 

Flexi· 

bility 

G 

G 

p 

F 

G 

F 

F 

F 

G 

G 

F 

p 

G 

G 

p 

p 

F 

F 

F 

G 

G 

G 

G 

G 

F 

F 

F 

Color 

Light green ____________ 

----.dO~----------------

____ .do _____ -----------. Brownish green. ______ Bottle green ___________ 

_--•. do ______ -_--------_ _____ do _____________ ---_ ---_.do ________ ------- __ Reddish rum to bottle 

green. 

Colorless to bottle 

green. 

Brownish green._----- ••••• do:... ______ ----.---. 

Rum ••• --------------- • ---~do ______ -_--------_ Bottle green ___________ 

---•• do .•..• -•• -~------- Brownish green _______ 

Brown .• -~.._- ___ • __ ---_ ~ ____ do· ______________ • __ 

Brownish r.um ________ 

___ .. do ______________ ·-.. 

Rum------------------

___ 

-~i~~~~~~~========= .. do ________ ~- _______ 

Light brown .. ~------- _. __ •• do ______ --------- __ 

1 Collection made and physical properties determined b'y Mr, ~awrence G. Houk, 1 Determined by National Bureau of Standards, · a See table, p. 147, 

Thickness 

(mm) 

0.12 

.16 

.08 

.14 

.15 

.23 

.11 

.16 

.2() 

.H 

.13 

.19 

.19 

.22 

.18 

.17 

.H 

• 21 

.23 

.17 

.15 

.17 

.11 

.15 

.15 

.18 

.17 

Power factor (percent) 2 

As received 

~~=8~ 

100 kc I 1000 kc I 100 kc I 1000 kc 

------ 0.08 0.02 0.05 . 0.02 

.02 .01 -------- --------

.04 .02 .03 .02 

.03 .01 -------- ------- .04 .02 .03 .01 

.01 <.01 -------- -------- .03 .01 -------- -----·-- .02 <.o1; -------- -------- .02 .oo -------- --------

.01 .01 .................. --------

.22 .03 .05 .01 

.22 .03 .12 .02 

.05 .02 .08 .03 

.01 .oo 

.05 <.01 .02 .01 

.08 .02 .04 .01 

.06 .04 .18 .13 

.02 .01 -------- -------- .05 .02 .04 .01 

.01 .00 -------- --------

.00 . 00 -------- -------- .02 <.01 -------- -------- .02 .01 -------- ______ ,__ 

.02 <.01 -------- -------- .12 .02 .03 <.01 

.04 <.01 .01 <.01 

<.01 .00 -------- --------

Remarks 

Slight ruling and few cracks. 

No imperfections; from center of same piece as preceding sample. Many hairline cracks. 

Wavy (slight brown line staining middle). Slight" A" ruling. Slight hairlining·on sides. 

Light-red dotted; not flat. 

From badly ruled "A" mica, under the 

apex. 

Do. 

Much wedge and "A" structure; slight hair lining. No imperfections.• 

Do.a 

Hairlines. 

Red stained, very light. Some hairlines but not obvious. 

Light-brown spotted. · Zoned coloring and organic staining. Slight tendency to develop hairlines when cut. Do. 

Zoned coloring. Tendency to develop hairlines. 

No imperfections. Slight ruling. 

No imperfections. 

.... 

~ 

~ ~ t::l 

lt! 

"tf 

0 

'(Jl 

~ '(Jl 

0 

l:j 

~ 

~ 

~ 

~ t;:1 

~ 

~ 
'MICA ·DEPOSITlr-GUATEMALA 147 

8prague;fa1Jrl,ootiOtt, te8t9 1Jy H. Braf~\on gooil stained~ stained A, atain.eil B, 

. tM~-il hOOIU'/I·BtaiMil m.Watrom 'EZ Anona no.·:1 mine 

Size------------~------------ 6,5~,5,4 

Color ------------------... ---- Green brown to rum. Splitting qualities____________ Good. 

Dielectric strength___________ Do. 

Power factor---------------- Do. 

"Q" qualifications : Good stained______________ About 2,500 

Stained A----------------- Do. 

Stained B----------------- Do. Heavy stained, lower _______ About 2,000 

Capacitor use: Good stained-------------- Good. 

Stained A----------------- Do. 

Stained B----------------- Do. 

Heavy stained------------- Too spotty, not recommended. 

Cleavage.-The most important property of mica is its cleavage, 

which permits crystals of normal muscovite to be split into sheets of 

uniform thickness. For marketing, the sheets must be trimmed to eliminate marginal imperfections. In contrast to the smooth cleavage 

surfaces afforded by normal mica crystals, some incompletely developed crystals, called "A" mica, are commonly wedge shaped anQ. irregular. Although some of these crystals have centers that yield flat 

mica, most of them must be discarded. A few Guatemalan deposits 

are made up entirely of "A" mica, but, fortunately, this variety is not 

of widespread occurrence. 

Flewibuity and elastiai.ty.-For many electrical uses sheet mica 

must be flexible and elastic. Common flaws affecting these properties 

are extremely fine fractures called hairline cracks, which have random orientation. Mica from most Guatemalan deposits shows t:hese 

flaws, and therefore may split poorly or be weak and brittle. However, hairline cracks are not present in all the mica crystals of a given 

deposit. Their cause is n·ot definitely known but appears to be related to the growth of the crystals and not to later deformation. 

Ool01'.-Most deposits of Guatemalan mica contain green crystals 

ranging from pale to deep bottle green or brownish green. Deposits 

of white, rum, or ruby mica are much rarer. Nearly all the mica 

shipped thus far has been green. 

Staining and inalU8ions.-Staining of either· primary or secondary 

origin may impair the value of sheet mica. Primary mineral stains 

are generally spots or films of iron oxides between the sheets, whereas 

secondary stains are due to infiltration of clay in the weathered zone. 

Primary mineral stains arefound in the-mica from many Guatemalan 

deposits, but heavily stained mica is not common. Inclusions of 

quartz, feldspar, and epidote in mica crystals are found in several 

deposits. Of these minerals quartz is the most abundant and generally occurs in layers that range in thickness from a. thin film to. o-:nefourth inch. Mica containing inclusions is ustmllydiscarded. 
148 MINERAL DEPOSITS OF CENTRAL AMERICA 

Natural distortion.-Distortion of mica crystals resulting from rock 

movements causes bending and ruling. These effects are generally 

most pronounced near faults. Although faults of any considerable· 

displacement are rare in the Guatemalan deposits, ruling and bendinK 

is present in some crystals from most deposits. 

Power factor.-The power factor, or loss of electrical energy, jn 

films of sheet mica used as the dielectric in condensers is expressed 

in percentage. A factor of 0.04 or less is usually required of mica forcondensers. The power factors of Guatemalan micas that have been 

measured are generally low. 

Water content.-Many Guatemalan micas when first quarried are--

quite soft because of water adsorbed between the sheets. The mica 

can be air dried or oven dried to remove the water, and it then becomes 

much harder. On cooling and standing, part of the water is again 

adsorbed, but the water content is lower than before. The origin of 

the adsorbed water is not clear. In part it may be water adsorbed 

during the rainy season. · · 

Production of mica in Guatemala has been hampered by several 

conditions. One of the most important is that operators can market 

only sheet mica; they now have to discard material suitable for scrap 

and punch mica because of the high cost of transportation. .Another isthat no effective organization exists for properly preparing and marketing the mica, and skilled miners and trimmers are not available. 

Also, many restrictions are placed on the use of explosives in mining in 

Guatemala, making large-scale operations difficult. No qnantitatived3ita are available on the cost of producing mica in Guatemala, but 

from past experience it is inferred that mica prices will have to remain 

at a high level if mica is to be exported. 

PACHALUM DISTRICT 

PALmATZ MINES 

The Palibatz mica mines (pl.14), the most productive in Gmitemala,_ 

have been credited with a yield of over 100,000 pounds of prepared 

sheet mica between 1918 and 1944. The mines, in the Departamento 

del Quiche, are the Palibatz no. 1, on a tributary of the Rio Caqufl 

about 5 miles east of Joyaba,j and 6 miles northwest of Pachalum, and 

the Palibatz no. 2, nearly a mile southeast of the Paliootz no. 1 

(pl.13). 

The deposi·ts were· first discovered about 1918 by Manuel Bergu8i 

and Ricardo Duhon. Mr. Bergua, with M.D. Heyman, Leon Campanolle, and others, began production.from the mines in 1923 and continued until1929. A small part of the mica was shipped to France 

and Germany, and the rest was shipped to the United States. Theearly shipments were of sheet mica, but la·ter, when punching machinery had been installed, washers, ·circles, and iron-planchas alro 
MICA DEPOSITS-GUATEMALA. 149 

were shipped. Production was intermittent from 1929 to December 

1940, when Manuel Bergua resumed operations and shipments until 

August 1944. The punching machinery is no longer in operation. 

The mica from the Palibatz no. 1 mine is light bottle green. Although shipments from this deposit probably exceeded 60,000 poUildS, 

the material was not of high quality because of its softness and hairline cracks. On the whole the mica splits well, but the sheets have 

only fair flexibility. The power factor of the mica as mined is high; 

however, that of the dried material is only 0.02-0.04 at 100 kilocycles. 

The sizes cut from the mica from the no. 1 mine pit have varied 

from time to ·time, depending upon the size and imperfections of. the 

books in different shoots. Some books that came from the south end 

of the pit were shipped as extra-special sizes as much as 5 feet in diameter, but the most common diameter was 8-18 inches. Recent work in 

the southwestern and northwestern parts of this pit have yielded 

books averaging 12 inches in diameter. A shipment made by Manuel 

Bergua had the size distribution shown in the table below. 

Size distribution of sheet mica from the Palibatz no. 1 mine, Guatemala 

Size t Weight Percent of total 

(pounds) weight 

~~~i~~~~::~==================================} 180 3. 5 

! ____________________________________________ _ 180 3.5 

2--------------------------------------------- 3 ____________________________________________ _ 360 7. 0 

450 8. 8 

1,260 24. () 

2,700 52. 6 

4---------------------------------------------

i~::=================::::::::::=:::::=========) Total __________________________________ _ 1----------1·---------

5, 130 100.0 

1 Standard Indi~ grades (Houk, 1942, p. 10). 

PALIBATZ NO. 1 MINE 

The Palibatz no. 1 mine (pl. 14) has yielded the major part of the 

mica produced. The main pit and several shallow cuts explore a pegmatite striking northward and dipping steeply westward, nearly parallel to the foliation in the enclosing biotite-muscovite and garnetandalusite schist and gneiss. Locally the pegmatite cuts the foliation 

and sends offshoots into the schist. The pegmatite has been explored 

in the main pit for 220 feet along the strike, for a width of 85 feet, and 

to a depth of 50 feet. 

The pegmatite contains a footwall zone, a central quartz zone, and 

a hanging-wall zone. The footwall zone is feldspar intercrystallized 

with quartz and in graphic intergrowth with quartz~ Mica is sparse 

in this zone and only one shoot has been mined (pl. 14, section A --A'). 
150 MINERAL DEPOSITS OF CENTRAL AMERICA 

This shoot was 4-5 feet wide by about 15 feet long and was in the :pegmatite at its contact with the central zone. Th~ central zone is· a 

quartz lens, as much as 30 feet wide, which is parallel to the strike 

and dip of the pegmatite except in a zone in the north-central part of 

the pit. This lens is composed of massive white· quartz and contains 

mica crystals of commercial size near its contacts with the enclosing 

pegmatite. When mining began, the quartz was exposed only in the 

northern part of the pit, but as the pegmatite was mined southward 

more quartz was exposed; when the pit was mapped the quartz lens 

was exposed for 140 feet. 

The hanging-wall zone of intercrystaUized coarse-grained quartz 

and feldspar contains the principal mica shoot, which was mined 

down the dip for 40 feet ( 80 feet below the surface) . It ranged in 

width from 6 to 15 feet and was 40 feet long. In 1944 mica still 

showed in the face and bottom of the pit. 

The feldspar in the pegmatite has been partly altered to clay minerals. This alteration is slight for the most part, but in the principal 

mica shoot much of the feldspar has been altered to soft clay minerals. 

As this alteration has no relation to the present surface, it is presumably related to the late-stage hydrothermal activity that introduced 

the mineral layers found in the mica books. Although the mica does 

not appear to have been much affected by this alteration, the softness 

and high water content may have been partly caused by it. 

The mica shoot mined in the southern part of the pit, near the portal 

of the adit, yielded books more than 5 feet in diameter. This shoot 

was mined to a depth o:f 40 feet, where there was still some mica ~n 

sight in 1944. Work done since 1943, when plate 14 was mapped, has 

penetrated 25 feet below the workings in the southwestern corner of 

the pit, where mica books 8-14 inches in diameter are still exposed on 

the walls of the stope. 

The mica shoot mined in the footwall of the quartz vein was nar- . 

row, ranging in width from 2 to 8 feet, but it had a total length of . 

more than 60 feet. At the face of the pit the shoot was cut off by the 

quartz vein. 

Mica continues into the shallow upper part of the pit, and stoping 

operations in 1944 deepened the pit about 10 feet more at the mica 

pocket shown in plate 14. Although the mica books averaged less 

than a foot in diameter, the material was relatively free from "A" and 

wedge structure and yielded a fair percentage of sheet mica. 

At the south end of the pit the pegmatite narrows abruptly and may 

pinch out entirely. However, exposures south of the dump, on the 

slope 250 feet from the pit, show a pegmatite outcrop 30 feet wide, and 

a shallow cut 60 feet long and 6-8 feet wide explores a mica shoot on 

the hanging-wall side of this pegmatite. Th~ mica in this cut is 

zoned; the crystals commonly show a light-green center zone 2-4 
MICA DEPOSITS-GUATEMALA 151 

inches in diameter, parallel to the prism, surrounded by an outer zone 

of brownish-green mica. The crystals range in diameter from 1 to 12 

inches and average 4 or 5 inches. Small crystals on the contacts of the 

pegmatite are greenish brown throughout. Although the mica in this 

cut is locally ruled and clay stained, it is fairly hard and splits well. 

It is of better quality than the light-green mica from the main pit, and 

further exploration may be warranted in the area south of the dump. 

PALIBATZ NO. 2 MINE 

The Palibatz no. 2 1nine is nearly a mile east of the no. 1 mine and 

is reached by a steep trail (pl. 13). Mica was first discovered here in 

1918, and sporadic attempts have been made to exploit the property. 

The property was idle from 1926 until1942, when Manuel Bergua reopened the workings and mined mica from the north and south pits. 

The workings (pl. 14), 3 open pits and several shallow cuts, explore 

a pegmatite sill striking nearly north and dipping 65°-75° W. in 

mica schist. Locally the contact follows the foliation of the schist, 

but more commonly it cuts the foliation. The mica zone is along 

the hanging wall of the pegmatite and is commonly confined to a zone 

10 feet or less in width. The feldspar is commonly white, but pink 

areas were seen in the south pit. Graphic intergrowth with quartz 

is common. Epidote crystals a few inches to 2 feet long are abundant 

in the north pit, particularly in the zone 5-15 feet from the contact. 

The mica is greenish brown and of medium hardness, and it splits 

well. It is superior in physical characteristics to the mica from the 

no. 1 mine pit, e:!rcept that its power factor is high. 

The north pit, 160 feet long, as much as 35 feet wide, and 30 feet 

deep, follows the hanging-wall contact of the pegmatite. Mica books 

6-14 inches in di:ameter are erratically distributed along the contact. 

The mica is most abundant at the north end of the pit, but even here 

it does not make up more than 5 percent of the rock. 

The central pit is 100 feet long but shows pegmatite for only 25 

feet. The mica books are as much as 14 inches in diameter; they are 

wavy and ruled, however, so that none of them can be used for sheet 

mica. Many mica books contain films of quartz and chalcedony between the leaves. Epidote crystals as much as 14 inches long were 

noted in the walls of the pit. 

The south pit is 80 feet long, as much as 50 feet wide, and its 

deepest part is about 50 feet below the surface. The pegmatite dike 

here is partly concordant and partly discordant with the foliation of 

the enclosing rocks (pl. 14, section A-A'). The mica shoot was about 

60 feet long and 5-15 feet wide. The books ranged from 4 to 12 

inches in diameter, and although the mica was of good quality the 

yield was not high. 

388364-57-11 
152 MINERAL DEPOSITS OF CENTRAL AMERICA 

EL ANONO NO. 1 MINE 

TheEl Anono no. 1 mine is 21;2 miles northeast of Pachalum and 

5 miles east of J oyabaj (pl. 13). The property was explored from 

1925 to 1928 by Manuel Bergua, who produced three or four hundred 

pounds of mica during these years. No mica was produced from 1928 

to 1942. During 1943 and until May 1944, Augusto Poitevin and 

associates resmned exploration and deepened the pit to determine the 

quality of the available mica. Work was continued slowly; about 200 

pounds of sheet mica was produced and sold in the United States. 

As mining costs were high and the books yielded only small sizes, 

the operation was not successful. 

The mine pit is 120 feet long, as much as 50 feet wide, and 65 feet 

deep (pl. 14). The pit explores a pegn1atite zone about 40 feet wide 

which strikes north to N. 15° vV. and is nearly vertical. The zone 

contains interfingered lenses of schist and pegmatite, and schist inclusions in the pegmatite have been feldspathized laterally from the 

feldspar veins. 

In the south end of the pit the pegmatite zone is 12-15 feet wide· 

and consists of 2 veins separated by a band of feldspathized schist. 

The pegmatite vein on the west contains a medial band of badly 

ruled and crushed mica 4-18 inches thick. The east vein is composed 

of coarse-grained white perthitic feldspar with spar.se irregularly distributed n1ica books 6-8 inches in diameter and some smaller broken 

books. 

At the north end of the pit the mica books are as much as 14 inches 

in diameter but are somewhat fractured and locally replaced by quartz 

and feldspar. Some books are almost entirely replaced, leaving 

oriented relicts of mica in the rocks; presumably the late solutions 

bearing quartz and feldspar came in along fracture zones and permeated the fractured areas. The mica books are irregularly distributed 

in small pockets and streaks in the pegmatite. Some hairline cracks 

are present in the Inica, but ".A" structure and ruling are not common_ 

EL ANONO NO. 2 MINE 

TheEl Anono no. 2 mine (pl. 13), about 500 feet south of the EI 

Anono 1, is at an altitude of about 4,250 feet. A trench 30 feet long 

and 20 feet wide, with an adit 8 feet long at the south end, explores 

a pegmatite 8-15 feet thick extending parallel to the foliation in mica 

schist, which strikes N. 15° W. and dips 30:> E. The pegmatite is 

mainly intergrown quartz and feldspar cut by veins and masses of 

quartz as much as 8 inches wide; the feldspar has been kaolinized. 

Brownish-green mica occurs in irregular pockets and is disseminated 

throughout the pegmatite. Most of the books are less than 4 inches in 

diameter, and although the mica contains little clay and iron oxide,.. 
MICA DEPOSITS-GUATEMALA 153 

much of it shows wedge structure, so that only a small percentage of 

it can be used. The deposit does not appear promising. 

XEABAJ MINE 

The Xeabaj mine (pl. 13) is 31;2 miles north of Caqu:ll, Departamento de Baja Verapaz, at an elevation of 5,950 feet. It was explored 

by Augusto Poitevin and his associates in April 1944 and produced 

255 pounds of mica. The workings explore a pegmatite sill, which 

cuts mica schist that strikes northward and dips steeply westward; it 

appears to be parallel to the foliation. The pegmatite is as much as 

50 feet wide where exposed in the pit. It is composed of intergrown 

quartz and feldspar; the feldspar has been completely altered to soft 

clay minerals, presumably by late hydrothermal solutions. 

The mica is light green and forms books from 4 inches to as much 

as 3 feet in diameter, the average dia1neter being about 1 foot. Most 

of the books are enclosed in the quartz masses, but some are in the 

adjacent quartz-feldspar rock. The principal mica shoot is on the west 

side of the pit, near the contact of the quartz and the hanging-wall 

schist. The shoot has been explored for a length of 30 feet and is as 

much as 15 feet wide. Shearing in the quartz along the hanging wall 

has caused ruling, bending, and fracturing in the 1nica. Many of the 

mica books show "A" structure, in spite of which they yield small 

sheets of good mica. Although the mica is unevenly distributed, the 

face at the time of visit showed 6-10 percent mica. The size distribution of sheet mica from the pegmatite is shown in the table below. 

Production at the time of visit (1943) was at the rate of 500 pounds 

of sheet mica a month, but because of the difficulty in marketing the 

mica the mine was closed in 1944. 

Size distribution of sheet mica from the Xeabaj mine, Guatemala 

Size 1 

Extra. speciaL _________________________________ _ A1 ___________________________________________ _ 

1--------------------------------------------- 2 ____________________________________________ _ 

:=============================================! 5 ____________________________________________ _ 

5%--------------------------------------------

6---------------------------------------------

Total __________________________________ _ 

1 Standard Indian grades (Houk, 1942, p. 10). 

EL CIPRES NO. 1 MINE 

Weight 

(pounds) 

5 

6. 2 

10. 3 

16 

24 

47. 3 

84. 5 

33. 6 

28.7 

255. 6 

Percent of total 

weight 

2. 0 

2.4 

4.0 

6. 3 

9. 4 

18 5 

33.0 

13.2 

11. 2 

100.0 

The El Cipres no. 1 mine (pl. 13) is half a mile northwest of the 

El Anono no. 1 property, at an altitude of 4,600 feet. This mine was 
154 MINERAL DEPOSITS OF CENTRAL AMERICA 

first explored during the 1920's by Manuel Bergua, who mined and 

shipped mica :from several pockets. In 1943 the property was acquired by Augusto Poitevfn and his associates, who did :further exploratory work but made no shipments. 

The pegmatite zone is 225 :feet wide and contains 2 pegmatites. 

'The principal pegmatite is 100 :feet wide and parallels the :foliation 

in the enclosing garnet-mica schist, which strikes N. 80° W. and dips 

•()5° S. The pegmatite is mainly intermingled quartz and :feldspar, 

hut near the center it contains a quartz core about 20 :feet wide that 

dips 50° S. 

The mica is light green; the books are 2--14 inches in diameter and 

average about 8 inches. Much of the mica shows "A" structure and 

is iron stained in places. Mica shoots were mined on both sides of 

the quartz; the hanging-wall shoot was as much as 6 feet wide and 

25 feet long, and the other comprised a series of irregular pockets. 

Mica made up 5-10 percent of the rock in the shoots, but amounted 

to only about 1 percent of the pegmatite as a whole. 

Another pegmatite-quartz sill 10-18 :feet wide is 75 :feet west of 

the principal pegmatite. This sill shows mica in a shoot 2--6 :feet 

wide, striking N. 60° W. and dipping 45° SW., parallel to the foliation of the enclosing schist. Part of the mica is in the quartz and 

part is in the pegmatite. The shoot has been opened for a length of 

about 60 feet. 

. EL CIPRES NO. 2 PROSPECT 

TheEl Cipres no. 2 prospect (p1.13) is half a 1nile west of Pachalun1, 

Departamento de El Quiche, at an altitude of 4,000 feet. The pegmatite is explored by a cut 40 feet long and as 1nuch as25 feet wide 

on land owned by Candelario Roca. No mica has been shipped frmn 

this mine. 

The pegmatite exposed is 20 feet thick and parallels the :foliation in 

the enclos1ng biotite schist, which strikes N. 50° W. and dips 40° SvV. 

It is chiefly feldspar but also contains quartz masses as much as 3 

feet wide and 10 feet long extending parallel to the strike. The mica 

is brownish green and occurs in books, 4-30 inches in diameter, w l1ich 

are for the most part associated with the quartz masses and contain 

quartz and some feldspar films between the leaves. Some books are 

replaced by quartz along their borders. Many of them are ruled and 

fractured and in some the mica is wavy. The mica is soft, and locally 

it is heavily stained with iron oxides; in some there is "A" structure. 

It is doubtful whether the deposit will yield commercial mica. 

LOS VOLCANCILLOS PROSPECT 

. The Los Volcancillos prospect (pl. 13) is 2¥2 miles southwest of 

Pachalum, at an altitude of 3,500 ~eet. The workings are 2 shallow 
MICA DE.POSITS__;GUATEMALA 155 

cuts, 35 and 15 feet long, which explore 2 pegmatites 4-12 feet wide 

composed chiefly of massive feldspar and graphic granite.· The pegmatites are parallel to the foliation in mica schist, which ·strikes 

N. 30° W.and dips80° SW. The mica books are bottle green and as 

much as 18 inches in diameter, averaging about 8 inches. Most of the 

books are badly ruled and are stained with clay and iron oxides; in 

places they are sericitized and replaced by quartz. None of the mica 

seems to be of commercial grade. 

SANTA ROSA PROSPECT 

The Santa Rosa prospect (pl. 13) is about 800 feet west of Pachalfun, 

on land owned by Rosalfo Estrada. A pegmatite dike of altered 

feldspar is explored in a shallow cut 12 feet long by 4 feet wide which 

was· dug by Augusto Poitevin and his associates. Bottle-green mica 

occurs in books averaging 3 inches in diameter. Much of it is wedge 

shaped and has hairline cracks. 

EI. JOCOTE PROSPECT 

TheEl Jo~ote prospect (pl. 13) is half a mile east of Pachalfun, on 

land owned by Simfon Elias. A pit 20 feet square and 8 feet deep 

was excavated by Augusto :Poitevin and associates. 

The pit explores a pegmatite, in altered gneiss, that contains sparse 

books of brownish-green mica that is heavy-stained to black-stained 

grade. Some books are a foot in diameter but have "A." structure 

imperfections and are ruled. The rest of them are small, averaging 

2 inches in diameter, and it is doubtful whether they will yield other 

than sizes 6 and 7. 

TZITZIL PROSPECT 

The Tzitzil prospect (pl. 13) is on the Rio Tzitzil, at an altitude 

o:f 5,350 feet. A pegmatite body, about 50 feet wide, can be traced 

for 500 feet along the strike. The pegmatite parallels the foliation 

in garnet-andalusite schist that strikes N. 75° W. and dips 65°-80° 

NE. Much of the body is concealed by vegetation and soil. Smaller 

pegmatite bodies are exposed nearby. A. few shallow cuts have been 

dug, but no mica has been mined. 

The mica is light green, forms books as much as 2 feet in diameter, 

and in places ·constitutes 2-5 percent of the rock. Most of the books 

are ruled and are stained with iron and vegetable matter. In places, 

thin quartz and feldspar layers appear between the sheets of mica and 

render the books useless. However; the mica is hard and flexible, and 

despite the low percentage of commercial mica in the outcrops and 

the cuts, further exploration of this deposit may be warranted. 
156 MINERAL DEPOSITS OF CENTRAL AMERICA 

SECHUN PROSPECT 

The Sechun prospect is a half mile northeast of El Peric6n, at an 

altitude of 4,150 feet, on the land of Juan Mulal. The property was 

explored in 1943 by Manuel Bergua, but no mica was shipped. 

The mica is in a pegmatite that parallels the foliation in garnetmica schist and interbedded limestone striking N. 50° ,V. and dipping 

50°-70° SvV. The pegmatite consists of quartz and feldspar and is 

exposed for a length of 50 feet and for a width of about 20 feet. The 

mica is light green and forms books 2-8 inches in diameter. Smne of 

the books are ruled and wavy, and others haYe inclusions of quartz 

and feldspar. · 

T ALAXC6C PROSPECT 

The Talaxcoc prospect (pl. 13) is a half n1ile east of El Peri con, 

at an altitude of 4,800 feet, on the land of Pablo Quiroga. 

A pegmatite sill, 10 feet wide, follows the foliation in mica schist 

for about 250 feet. The foliation strikes N. 55° W. and dips 50° SW. 

A few lenses 2-5 feet long contain books of rum -colored mica 2-6 

inches in diameter. Most of .the books are stained with iron oxides 

and some have "A" structure. 

LOS TABLONES PROSPECT 

The Los Tablones prospect is 1 mile southwest of the town of Volcancillos at an altitude of 3,400 feet. The prospect was explored by 

Augusto Poitevin and his associates in1943, but no mica was produced. 

Mica schist, striking N. 55° E. and dipping 40°-70° NW., is the 

walt rock of a pegmatite sill 30 feet wide than can be traced for 200 

feet along the strike. The mica is light greenish brown ·and forms 

books, as Inuch as 8 inches in diameter, which occur sporadically 

throughout the pegmatite. As n1ost of the books are stained black and 

red and are wavy, the prospect does not appear promising. 

QUIAC6J PROSPECT 

The Quiac6j prospect (pl. 13) is just south of the Rio Pasaguay, 

at an altitude of 4,650 feet. A cut 50 feet long and 10 feet wide which 

exposes pegmatite was dug by Manuel Bergua in 1943. No mica was 

shipped. 

The pegmatite is chiefly feldspar with masses and lenses of quartz. 

It follows the foliation in mica schist striking N. 30° W. and dipping 

35°-60° SW. At the cut the pegmatite is about 40 feet wide, and 

it can be traced for 100 feet in both directions along the strike. The 

mica is dark green and forms books as much as 12 inches in diameter, 

averaging about 6 inches. Much of the Inica is heavily stained and 

shows ruling and some "A" structure. At the north end of the cut the 

mica has been sheared by a fault striking N. 70° E. and dipping 

65° SE. 
MICA DEPOSITS-GUATEMALA 157 

ACUA CALIENTE DISTRICT 

The Agua Caliente district lies north of the village of Granadas, 

which is on the Coban.;Guatemala City highway. The 1nines (pls. 13, 

15) can be reached by a trail that leaves the highway at the 80-kilon1eter 

post and continues up the valley of the Rio Agua Caliente. 

LA ADILIA MINE 

The La Adilia. mine is 3 n1iles southwest of El Chol, at an altitu~e 

of 3,700 feet (pl. 13). The workings (pl. 15), two groups of pits, are 

on a ridge south of the Rio Agua Tibia. The property was worked 

intermittently during the 1920's and early 1930's but has since been 

idle. Eduardo Aparicio held the exploitation license in 1945. 

The west group of workings consists of 2 opencuts, the main one 

of which is 400 feet long and explores a pegmatite of irregular shape 

enclosed in mica-feldspar schist striking northwestward and dipping 

steeply. 'fhe pegmatite, exposed over a width of 40 feet, is composed 

of an outer zone of feldspar and quartz and an inner core of quartz. 

The quartz core is as much as 17 feet wide and is exposed for 85 feet 

along, the side of the opencut. The pegmatite on the east side of the 

quartz ranges in width from 4 feet to more than 15 feet and is the 

host rock for the mica that has been mined. The pegmatite narrows 

and pinches out at the south end of the cut but appears to widen at 

the north end. Most of the slope west of the cut is covered with soil, 

and the pegmatite can be seen only in the haulage portal. The principal mica shoot was mined from the pegmatite and adjacent quartz 

vein. The shoot was 80 feet long and as much as 20 feet wide and was 

mined to a depth of 40 feet in the southern part. Although the mica 

zone was not exposed in 1943 because the pit was caved, commercial 

mica is reported to occur at depth. Judging from reports, and ex:.. 

posures in the walls of the pit, the books were 6 inches to 2 feet or 

more in diameter and averaged about 12 inches. 

The east workings are 4 shallow pits, which explore a pegmatite 

adjacent to 2 quartz lenses. The workings north of the main pit are 

partly caved and do not show any good mica. 

The main pit, 45 feet long and 30 feet wide, shows a pegmatite 

striking northeastward and dipping gently northwestward that cuts 

mica and hornblende schist in which the foliation strikes northwestward and dips steeply southwestward. The pegmatite has yielded 

mica near the hanging wall from a shoot that is now covered with 

waste. 1\Hca in pegmatite in the pit south of the main pit is of low 

grade. 

LA CONSTANCIA MINE 

The La Constancia mine is 21h miles southwest of El Chol, on the 

land of Pedro Galiano (pl. 13). Arthur W. Chellis worked this mine 

in 1918 and for a few years afterward, and during the late 1920's it 
158 MINERAL DEPOSITS OF CENTRAL AMERICA 

was exploited successively by R. A. Loomis, Sr. Bustamante, Juan 

Ureve, Juan Fricke, and Otto Tischler. The last shipments were 

made in 1929. 

The workings (pl. 15) are in a flat-lying pegmatite that cuts mica 

schist, which strikes northwestward to westward and dips steeply 

southward. The pegmatite is exposed in the workings for a length of 

350 feet, and outcrops to the east and west indicate that its length 

is about 2,000 feet. As the workings are on a terrace, the schist 

hanging-wall zone is thin, ranging from a foot or less on the south 

side of the pit to 6 feet on the north and east sides. 

The mica is greenish brown for the most part, but some books in 

quartz are light green. The books are 2 to 18 inches in diameter and 

have yielded mica predominantly of sizes 3 to 6. The mica splits 

well but is soft, and hence it is suitable principally for _electrical uses. 

LA VmGINIA MINE 

The La Virginia property is a mile west of the La Constancia workings (pl. 13). Although the deposits have been known for many years, 

no mica has been produced from them. In June 1944 Eduardo 

Aparicio and ,Jose Montufar began exploration on one of them. 

The workings (pl. 15) comprise several shallow cuts in bodies of 

pegmatite and quartz whose form is not known, but the foliation of 

the enclosing schist strikes westward and dips southward 45°-70°, 

and presumably the pegmatite cuts the foliation. One of the quartz 

lenses trends northeastward and the other northward, crossing both 

the foliation and the pegmatite. 

Exploratory work has revealed mica in the pegmatite along the 

quartz masses, and the most promising cut is adjacent to the quartz 

lens trending northeastward. There the pegmatite has been explored 

for 40 feet along the strike and for a width of 30 feet. The mica is 

brownish green and somewhat stained with clay and iron oxides at 

the surface; the books average about 12 inches in diameter. Ruling 

and "A" structure are present in places, and only a little good mica can 

be recovered. Not enough work has been done to determine the percentage of recoverable sheet mica. 

LA ESPERANZA MINE 

The La Esperanza mine is 21h 1niles northwest of Granadas (pl. 13), 

on land owned by Tiburcio Xetumul, at an altitude of 4,600 feet. The 

mine was first operated in 1919 by Arthur W. Chellis and Adolfo Benz. 

Mica was shipped between 1919 and 1923; the exact production is not 

known. There was no activity from 1923 to 1942, and between 1942 

and 1944 Adolfo Benz h. reopened the pit but produced no mica. 

The mica is in a feldspar-quartz pegmatite as much as 75 feet wide 

which lies between a massive quartz vein and mica schist (pl. 15). On 
MICA DEPOSITS-GUATEMALA 159 

the west the pegmatite is locally faulted along the contact. The mica 

shoot is on the southwest side of the pegmatite, and where exposed in 

the workings it is 3 feet wide and 10 feet long. Near the fault the mica 

is ruled, but elsewhere there is little ruling. The mica is greenish 

brown and on the whole splits well. As only a few books were exposed 

in the pit, the average size is not known. Since a fair production is 

reported from this property~ it seems reasonable that further work will 

yield electrical mica of marketable sizes. However, any future exploration will have to be und~rground. 

NUEVA WELLINGTON MINE 

The Nueva Wellington mine (pl. 13) is about 500 feet north of the 

La Esperariza mine, in the same pegmatite zone. The workings consist of an open pit 30 feet deep and several opencuts (pl. 15). The 

property was worked at the san1e tilne as the La Esperanza and by the 

same operators, and it has a similar history. In 1943 Adolfo Benz h. 

mined some 1nica from the pits but no shipments were made. 

The pegmatite at the Nueva Wellington is ·in mica schist, which 

strikes northwestward and dips steeply southwestward. The pegmatite occupied nearly the whole of the main pit, but it narrowed 

downward, and what remains is now largely covered by waste rock 

in the bottom of the pit. At the south end of the pit the pegmatite is 

reported to have split, one tongue going westward and the other southward toward the quartz vein. 

The mica from the pit is green. The books are heavily clay stained 

and, in places, heavily mineral stained. Exploration in 1943 had not 

reached unaltered pegmatite, so the quality of the mica at depth was 

not known. The books are as much as 2 feet in diameter, and where 

not clay stained have yielded mica of fair quality. The hardness is 

fair, but smne books split poorly. 

LA CABRERA MINE 

The La Cabrera property is about 2lf2 miles northwest of the Nueva 

Wellington mine (pl. 13). Adolfo Benz h. explored the property in 

1943, and from a cut 40 feet long and 6 feet wide recovered 800 pounds 

of book mica, which yielded 245 pounds of sheet mica. 

The pegmatite is parallel to the foliation in the enclosing schist, 

striking N. 45° W. and dipping 40°-50° SW. The pit was filled in 

1944, but judging from specimens on the dump some of the mica appears to have been ruled and bent. The mica is dark browiiish green 

and is reported to average 12 inches in diameter; some books are as 

much as 18 inches across. Clay staining was noted in the surficial mica. 

About 400 feet to the northeast a shallow cut exposes another pegmatite, which is 12 feet wide and 30 feet long. There are only scattered books of mica in the cut; the crystals seen were dark brownish 

green, fairly hard, and easy to split. 
160 MINERAL DEPOSITS OF CENTRAL AMERICA 

LIBERTAD AND MARGARETA PROSPECTS 

The Libertad and Margareta prospects (pl. 13) are about 31f2 miles 

northeast of San Rafael Salbin, on land owned by Domingo Soto and 

Luis Ortega. The workings consist of several shallow cuts in pegmatites, which crop out for a distance of 1,500 feet along a ridge trending northward, at an altitude of 4,750 feet on the south and about 

4,900 feet on the north. In 1942, Emilio Estrada and Domingo Soto 

began to explore the deposits. In 1943 Augusto Poitevfn continued 

exploratory work and made a shipment of 134 pounds of mica to be 

used for samples. 

The pegmatite bodies appear to be sill-like and crop out in areas as 

much as 300 feet long by 60 feet wide. Forest cover and heavy soil 

prevent exact determinations of their size, but at the north end of 

the Libertad area 1 pegmatite body appeared to be about 100 feet 

thick. The pegmatites are chiefly feldspar with a little quartz. In 

places the feldspar is altered to clay minerals. The wall rock is chiefly 

hornblende schist and mica schist, which in this area strike N. 35°-70° 

W. and commonly dip northeastward. 

The mica is rum colored and forms books that average 5 inches in 

diameter, with a maximum of 16 inches. It is sparsely distributed 

throughout most of the peg~natite but forms at least 1 shoot 40 feet 

long and 5 feet wide. Considerable clay and iron staining, ruling, 

wavy structure, and some wedge structure are present. 

A shallow pit nearby may be in a pegmatite that is a continuation 

of those in the Libertad-Margareta group. The pegmatite contains 

a little rum mica, which is stained and shows hairline cracks. 

EL PEREZ NO. 1 MINE 

TheEl Perez mine (pl. 13) is 2 miles south of Salbin, on land owned 

by Flavio EHas. An opencut 8 feet wide by 12 feet long explores a 

quartz-feldspar pegmatite 3 feet wide in garnet schist. The rock 

contains about 1 percent white to light-green mica in books averaging 2 inches in diameter. The mica is stained, of "A" type, and principally size 6. In 1943 between 200 and 300 pounds of marketable material was produced. 

EL PINO PROSPECT 

TheEl Pino prospect {pl. 13) is 5 miles northeast of Salbin, on the 

land of the EHas brothers. Three shallow pits put down by Augusto 

Poitevin and his associates explore a soft altered pegmatite 8-20 feet 

wide, which crops out for 150 feet along its N. 25° W. trend. Rumcolored mica makes up as much as 7 percent of the rock. However, the 

crystals average only 4 inches in diameter and some of them· are wavy 

and show ruling. 
MINERAL DEPOSITS OF CENTRAL AMERICA 

QUARTZ DEPOSITS 

GUATEMALA 

161 

Deposits of quartz crystals in Central America have been exploited. 

only in Guatemala. Although production has been small, the deposits 

are widely distributed throughout central Guatemala, chiefly in the 

Departamento de Baja Verapaz and Departamento del Quiche. 

The principal producing areas (fig. 14) are near the villages of Rabinal, Cubulco, and El Chol (L. G. Houk, 1943, unpublished report). 

Deposits are also found in the Departamento de Progreso, but only 

two have been in production. 

Quartz mining first began in Guatemala in 1941, when some usable 

material was found in uncobbed crystals ship~ed to the United States 

on consignment, in response to the increased demand for quartz oscillator plates at the beginning of World War II. Early shipments to the 

United States brought little return because the material was of low 

grade and specifications at that time were high. Later, however, 

with lowered specifications and increased prices, quartz-crystal mining became profitable, and several producers operated proper,ties dur-. 

ing 1943 and 1944. Their product was purchased directly in GuateEXPLANATION 

~ 

',,\ 

'--------'---·~--2 Miles\ 

0 BuenaVista 

FIGURE 14.-Map of Cubuleo, Guatemala, showing location of the quartz mines. 
162 MINERAL DEPOSITS OF CENTRAL AMERICA 

mala by the Foreign Economic Administration; production ceased 

early in 1945 when this program was discontinued. 

The following table summarizes the production of radio quartz of 

grades 1, 2, and 3 in Guatemala from 1941 to 1944. · · · 

Radio-quality quartz produced in Guatemala, 191,.1-1,.1,. 1 

VAar Mine 

Weight (pounds) by grade 2 a 

Value« 

(dollars) 1 2 3 

1941_ ____ Toloxcoco ________________ -------- 8. 17 13. 04 142. 61 

1943 _____ _____ do ------------------ 37.52 7. 49 41. 42 595. 29 Do ____ 

~f~~~f~s!~t~- iuci~L-~ = = = 

-------- -------- 28. 69 212.48 

Do ____ -------- 6. 75 166. 66. 381. 32 

Do ____ Xeul 5 ____________________ 17.38 135. 09 117. 30 II 1, 339. 99 1944 _____ _____ do ___________________ 5. 22 72. 93 11. 23 539. 92 

Do ____ El Chol (Santa Lucia) _____ 2. 62 37.27 5. 21 301. 17 

Do ____ Los Limones ______________ 13. 56 187. 41 36.62 1, 635. 38 

Do ____ Los Cimientos ____________ 25.05 8. 89 -------- 125. 64 Do ____ Chinique _________________ . 50 7. 77 9. 16 37. 16 

Total ______________ 101. 85 471. 77 429. 33 5, 310. 96· 

1 Data taken from Foreign Economic Administration reports. 2 Grading was based on the following percentages of usable material: grade 1, more than 65 percent usable; 

grade 2, 4Q-65 percent usable, grade 3, 25-40 percent usable. a Average weight of cob bed fragments was about 1.2 pounds each. t Average price per pound was $5.29. s Also includes some quartz from the Izotal, RabinaH"i, and Dolores properties. e Based largely on grading done in Guatemala City by the Foreign Economic Administration, which 

averaged about 2.0 percent higher than that graded by the National Bureau of Standards. Payment was on the basis of the grading by the Foreign Economic Administration. -

GEOLOGY 

The quartz deposits occur as veins and lenses in the pre-Per1nian 

belt of metamorphic rocks that make up central Guatemala. The 

wall rocks are garnet-mica schist and gneiss, hornblende schist, marble, 

and andalusite schist, which in places have been intruded by granitic 

rocks. A zone of pegmatite and aplite dikes extends southward and 

westward from the granite west of Cerro Tuncaj ; the zone may be 

related to the granite. Quartz veins, some enclosing rutile crystals, 

are found with the pegmatites, but none of these veins have yielded 

commercial quartz crystals. 

The quartz deposits are chiefly glassy crystalline quartz, which is 

commonly anhedral and is rarely euhedral. The euhedral crystals 

generally occur in vugs, but some are in veins whose crystals are arranged in parallel comb structure. Other crystals are isolated in 

altered wall rock. 

Some of the anhedral crystalline quartz of the massive deposits is 

clear enough to furnish radio-quality material; however, much of it 

is worthless because of inclusions or fractures. The vugs in the massive quartz contain euhedral crystals weighing as much as 400 pounds 

apiece~ but the largest crystal of commercial grade' that" was shipped 
QUARTZ DEPOSITS--GUATEMALA 163 

weighed 52 pounds. Commonly the basal part of a crystal is milky 

or contains inclusions, and only the upper part yields radio-quality 

material. 

Most of the Guatemalan quartz is colorless or milky white. Some 

smoky quartz was found at the Izotal deposit, and a little amethystine 

quartz is reported from a deposit near Rabinal. The amethyst is not 

of gem quality. 

Most of the quartz deposits that have been mined are lenticular 

veins, but some are irregular masses and a few are veins of fairly 

regular thickness. The quartz fills fractures in the enclosing rock 

and to some extent replaces the rock adjacent to the fractures. 

Although locally the veins follow the foliation, most of them cut 

across it. At the Toloxcoco mine (pl. 16) the quartz lenses cut the 

foliation and are distributed in echelon, which indicates that they may 

fill tensional gash fractures. The irregular masses generally occur at 

the intersections of fractures or fracture systems. 

· The euhedral quartz crystals are generally well developed hexagonal prisms with pyramidal terminations, and some show trapezohedral and rhombohedral faces. The ratio of diameter to length differs 

from one deposit to another; at Toloxcoco the average is about 1: 4. 

The accessory minerals that accompany the quartz veins include 

rutile, chlorite, orthoclase, plagioclase, ilmenite, and pyrite. The 

rutile forms prisms as much as 4 inches long, and also slender needles; 

most of the larger crystals are embedded in fine-grained quartz, 

whereas the needles are generally enclosed in quartz crystals. Ilmenite 

accompanies rutile in some veins. Chlorite is found as an alteration 

product of· the hornblende and biotite in schist wall rock adjacent to 

veins and also as inclusions in the quartz crystals. Orthoclase and 

plagioclase are found locally in quartz veins; they may be intergrown 

with the quartz or may form euhedral crystals that lie between quartz 

crystals or coat the faces of quartz crystals in drusy cavities. Pyrite 

is a constituent of a few veins, especially at Los Limones. 

Few of the quartz crystals found in Guatemala are perfect and clear. 

The imperfections that affect the value of the quartz are inclusions, 

minute fractures, and twinning. Some crystals are milky, owing to 

bubbles and clouds of inclusions. Stages in the growth of some crystals are marked by alinement of inclusions and vacuoles. Crystals 

from Toloxcoco contain chlorite inclusions alined parallel to former 

faces in the interior of the crystals. Hard blue needles of a mineral 

thought to be rutile are found in some crystals but are relatively rare. 

Besides the distinct fracturing found in nearly all deposits, the quartz 

from deposits at Santa Lucia, Los Limones, and Chinique shows minute fra<?tures. Pieces as mined are clear and appear sound, but whPn 

cob bed they break with a hackly rather than conchoidal fracture; 
164 MINERAL DEPOSITS OF CENTRAL AMERICA 

the fracture ~urface is ruled by a rectangular network of fine grooves 

and ridges, probably caused by the intersection of minute fractures 

and conchoidal fracture surfaces. Some crystals disintegrate when 

struck lightly with a hammer, breaking into irregularly shaped fragments and slivers. In addition to the minute fractures, crystals from 

many deposits contain more marked fractures that cause the quartz 

to break when they are being cobbed; the fragments are too small for 

commercial use. Some crystals do not develop fractures when cobbed, 

but when sawed they may disintegrate and be worthless for radio 

work. Such crystals when placed in an oil bath and viewed under a 

strong light in a dark field show numerous fine parallel lines, which 

on rotating the crystal reflect light and prove to be minute fractures. 

Extremely fine fractures show hazy reflected light, similar to that 

shown by the blue needles, and it may not always be possible to·determine whieh of the two is present. 

Although twinning is not common in Guatemalan quartz, some crystals and parts of crystals are twinned, either optically or electrically. 

Optical twins, when placed in an oil bath and viewed in polarized light 

along the c axis, appear as triangular areas bounded by straight lines. 

Electrically twinned erystals show irregular boundaries when viewed 

the same way. EL CHOL AREA 

The Santa Lucia, Los Limones, and several small prospects in this 

area have yielded radio-quality quartz. 

SANTA LUciA MINE 

The Santa Lucia mine is half a mile east of El Chol, Departamento 

de Baja Verapaz, at an altitude of 3,700 feet (pl. 16). Two pits that 

explore quartz veins trending northwestward have yielded about 175 

pounds of radio-quality quartz, mostly grade 3. The quartz shows 

minute fractures, bubbles, and random inclusions of chlorite. Production began in 1943, when Carlos Guzman, of Guatemala City, 

opened the mine. Shipments eeased when the easily exeavated material was quarried and it was learned that much of the quartz was 

not of radio quality because of minute fractures. The workings are 

in biotite schist; here the schist has been cut by small dikes of pegmatite and aplite. 

Pit 1 yielded about 85 pounds of quartz from a pocket separate from 

the main zone, which is in the northwest corner of the pit. The face of 

the eut in 1944 showed branching veins of milky quartz along fractures 

in the schist. The veins are narrow and much fraetured. Exploration 

along the strike of the float zone to the southeast was not promising. 

Two quartz veins in pit 2 trend northwestward and dip steeply 

southwestward. Pit 2 yielded about 90 pounds of usable quartz at the 
QUARTZ DEPOSITS-GUATEMALA 165 

junction of 2 veins, which were covered with debris in 1944. The 

crystals were embedded in brownish clay formed by alteration of the 

biotite schist wall rock. 

LOS LIMONES MINE 

The Los Limones quartz mine is 31h miles southeast of El Chol, 

on the land of Agustin Cordoba (pl. 16). Carlos Guzman explored 

this deposit in 1944 and shipped about 220 pounds of radio-quality 

quartz from a pit 40 feet long and 6-10 feet deep. The quartz was 

found in two oval-shaped pockets; the larger one was in the northwest corner of the pit. 

The bedrock in the area consists of hornblende-mica schist which 

for the most part strikes northwestward and dips steeply southwestward. Near the quartz pockets and between them, the schist is altered 

to a reddish-brown clay. The quartz pocket has an outer zone of milky 

quartz and an inner core of euhedral crystals with some clear areas. 

One exceptional crystal weighed 52 pounds and was valued at $589. 

The quartz was mostly of grade 2. Some of it showed minute fractures and had to be discarded. 

On the southeast side of the pit a quartz vein about 4 feet thick is 

exposed. The vein and the adjoining pocket is of milky quartz, and 

milky-quartz float continues north of the pit for 350 feet. Specimens 

collected on the surface showed muscovite crystals, as much as an inch 

in diameter, and a little ilmenite and rutile. 

TRAPICHE VIEJO MINE 

The Trapiche Viejo quartz mine is on the Rio San Pedro, 51h 1niles 

southwest of El Chol, at an altitude of 2,900 feet. The deposit was explored in 1944 by Carlos Guzman, who opened a cut 50 feet long by 25 

feet deep, in the face of which the vein is exposed. About 75 pounds 

of commercial quartz was produced from the property. 

The vein strikes N. 15° E. and dips 80°-85° NW. in hornblende 

schist whose foliation strikes N. 80° E. and dips 40° SE. The vein is 

21h-7 feet wide and has been sheared and broken by faulting. The 

quartz is for the most part milky or cloudy, but some crystals with 

clear areas have been found. 

At Las J obas, a mile west of Trapiche Viejo, a deposit of quartz 

crystals is said to have been found, but it had not been explored. 

LOS AMATES DEPOSIT 

The Los Amates quartz deposit is 31h miles northeast of El Chol, at 

an altitude of 4,200 feet. .A.t this place a quartz vein, judged from 

float on the slope to be about 10 feet wide, is poorly exposed in a cornfield. The quartz is milky but contains cavities lined with small clear 

crystals, none of which were large enough for commercial use. However, light-green muscovite crystals 1-6 inches in diameter are spo-
166 MINERAL DEPOSITS OF CENTRAL AMERICA 

:radically distributed throughout the quartz, and their presence indicates that the vein is a pegmatite. 

RA.BINA.L AREA. 

TOLOXCOCO MINE 

The Toloxcoco deposit is near the village of Chirrum, 7 miles 

southwest of Rabinal, Departamento de Baja Verapaz. The workings (pl. 16) are at an altitude of 4,500 feet on the slope of a hill 

known locally as Cumatza. The deposit was worked intermittently 

from 1941 to 1944. The first shipment of Guatemalan quartz came 

from this deposit; it was made by Toriello Brothers, of Guatamala 

City, which sent a 500-pound lot of uncobbed material to the United 

States. In 1942 H. J. Nicol shipped 2,800 pounds, from which no. 

usable crystal was recovered. In 1943, Raul Perdomo and Carlos 

Guzman began operations and shipped 136 pounds, from which 27.5 

pounds of grade-1 quartz, 7.5 pounds of grade-2 quartz, and 41.4 

pounds of grade-3 quartz were sorted. Since 1943 no quartz has been 

produced, principally because the easily ,recoverable quartz has been 

mined, and explosives would now be necessary to do underground and 

surface work. 

The quartz is in lenses and veins that cut hornblende schist whose 

foliation strikes northward and dips 40°-60° W. The deposits are· 

gash veins striking northeastward and dipping 30°-50° SE., nearly 

normal to the foliation and arranged in echelon. 

The quartz bodies are lenses a few feet to 35 feet long and as much 

as 4 feet thick; they have been mined down the dip for as much as 

25 feet. Commonly the lenses consist of finely to coarsely crystalline 

quartz with euhedral crystals lining the cavities. The wall rock 

around the quartz is generally altered to soft chloritic material, now 

partly oxidized. The alteration was pa.rt of the vein-forming process,. 

for chlorite is enclosed in the quartz along the margins of the veins 

and in places occurs in crystals lining the vugs. 

Quartz deposits on land of Ignacio Gonzales, about a mile southeast 

of Toloxcoco, were explored in 1943 by Raul Perdomo. Several smoky 

and cloudy crystals were found on the surface and in the soil mantle .. 

A cut 30 feet long, 30 feet wide, and 12 feet deep was dug in altered 

mica gneiss to explore the deposit at depth. A quartz vein 6 inches. 

wide, striking N. 40° W. and dipping 55° SW., shows in the pit; it 

contains fine-grained quartz in crystals that are too small for commercial use. 

CHIPACAPOX MINE 

The Chipacapox quartz deposit, 31h miles east of Rabinal, was explored in 1943 by Raul Perdomo. About 28 pounds of quartz crystals,. 

of grades 2 and 3, was produced. Imperfections in the crystals in-· 
QUARTZ DEPOSITs-GUATEMALA 167 

elude bubbles, clouds, and twinning. The outlook for future production is reported to be promising. 

CUBULCO AREA 

XEUL MINE 

The Xeul mine is about 6 miles southeast of Cubulco, in the Sierra 

de Chuacus (fig. 14), at an altitude of 4,500 feet. It is on the property 

of Soledad Reyes Fernandez de Garcia and has been exploited since 

1943 by Victoria Mota de Ruiz. The workings (pl. 16) consist of an 

opencut, 90 feet long and as much as 80 feet wide, which has produced 

about 350 pounds of usable radio quartz. Most of the quartz was of 

grades 2 and 3, but 22.5 pounds of grade 1 was included. 

The quartz deposits are in hornblende schist, mica schist, and gneiss 

in which the foliation strikes N. 20°-50° E. and dips 40°-50° NW. 

These rocks are altered to a soft reddish-brown chloritic material near 

the veins and pockets in which the quartz crystals occur. The veins 

appear to strike northwestward and to dip steeply southwestward. 

The crystals range in weight fron1 a few ounces to 500 pounds. Most 

of them are milky and enclose bubbles and chlorite flakes; in some 

crystals these inclusions are arranged in zones that outline early 

crystal faces. 

The major part of the production came from the two pods exposed 

in the southwestern part of the pit. They are estimated to have 

yielded about 8,000 pounds of quartz. No quartz is now showing in 

this part of the pit, and the two veins in the northern part show only 

fine-grained quartz. All the easily accessible quartz has been mined, 

and the present shows are not pron1ising. However, it seems likely 

that further exploration might yield pockets of usable quartz crystal 

IZOTAL MINE 

The Izotal mine is 1,700 feet southwest of the Xeul deposit. A pit 

50 feet long, 20 feet wide, and 12 feet deep was excavated in weathered 

gneiss striking N. 30°-40° E. and dipping 70°-85° SE. A few small 

quartz veins and lenses, which cut the foliation, were mined, yielding 

about 400 pounds of quartz crystal, which was cobbed to 75 pounds 

of usable material. 

SAN JUAN PROSPECT 

The San Juan prospect is a mile southeast of Sutun, a village on 

the Rabinal road, and is 2 miles southeast of Cubulco. A shallow pit, 

in schist and gneiss whose foliation strikes N. 30° W. and dips 55° 

SW., has yielded white milky quartz and two crystals of rose quartz. 

The deposit does not appear promising. 

3S8364--57----12 
168 MINERAL DEPOSITS OF CENTRAL AMERICA 

CHIRRUMAN PROSPECT 

The Chirruman prospect is a mile south of Sutun, on land owned 

by Ernesta Reyes. An opencut 10 :feet long shows quartz fragments 

in a fracture in altered gneiss. A feldspar, probably albite, coats 

some of the quartz crystals. The foliation of the inclosing gneiss 

strikes N. 45° '""·and dips 60° SW. 

EL CANDON J>ROSPECT 

The El Cand6n prospect is half a mile south of the Chirruman 

deposit, at an altitude of 3,900 :feet. Three narrow quartz veins dip 

northward at low angles in altered mica schist that strikes N. 30° E. 

and is vertical. Albite crystals as much as 4 inches long are associated 

with the quartz and occur as coatings on the :faces of quartz crystals. 

POMAxAN P:ROSPECT 

The Pomaxan quartz prospect is about 2 miles N. 60° W. of Cubulco, 

at an altitude of 4,250 feet. The exploratory workings consist of a 

shallow cut 20 feet long which shows a quartz vein, striking N. 75° E. 

and dipping 35° SE., that cuts augen gneiss. The vein is as much 

as 3 feet wide and, except for a few clear crystals less than 2 inches 

long, is fine grained and milky; therefore it is not radio-quality 

material. 

PARAXA PROSPECT 

The Paraxa prospect is a mile southwest of the Pomaxan prospect, 

at an altitude of 4,950 :feet. The workings consist of two opencuts, 

which explore quartz in 1nica schist on a narrow ridge. The schist 

strikes N. 15° W., transverse to the ridge, and dips 40° SW. The 

quartz vein strikes N. 70° W., parallel to the ridge, and dips steeply; 

it ranges in width from a few feet to 20 feet and can be traced for 

70 feet along the strike. Locally the vein contains feldspar, probably 

albite, which is intergrown with the quartz. The quartz is milky and 

fine grained. A :few vugs contain clear crystals, but they are too small 

to be of value for radio quartz. 

Other quartz deposits south of Paraxa have been explored by shallow cuts, but none of them are promising because the quartz in them 

is fine grained and milky. 

CHAUTULUL PROSPECT 

At the Chautulul prospect, a mile southeast of Cubulco, small quartz 

stringers striking N. 40° E. cut altered gneiss. All the crystals found 

thus far are small. Other quartz deposits about 1,500 :feet to the 

northeast include veins and a mass of quartz 3 feet in diameter. No 

commercial quartz has been :found in either deposit. 
QUICKSILVER DEPOSIT8-HONDURAS 169 

DOLORES DEPOSIT 

At the Dolores deposit, 21h miles southeast of Cubulco, 65 pounds 

of grade 3 quartz is reported to have been produced from 1 quartz 

vein. Most of the quartz showed clouds, blue needles, and twinning. 

The deposit is said to be mined out. 

OTHER DEPOSITS 

Quartz prospects near Rabinala, a village about 81h miles west 

of Cubulco, have been worked by Francisco Garcia. About 60 pounds 

of radio-quality quartz of grades 2 and 3 has been cobbed from 

shipments. Its imperfections include clouds, soft blue needles, and 

twinning. The deposit was not visited, but according to Senor 

Garcia the easily accessible material has been mined out. 

A quartz deposit 8 miles north of Chinique, Departamento de El 

Quiche, was explored by H. J. Nicol in 1944. About 17 pounds of 

quartz, largely of grades 2 and 3, was produced. As the quartz 

showed minute fractures and the vein was small, the operation was 

abandoned. 

Quartz deposits at Los Cimientos, 15 miles north of El Rancho in 

the Departamento de Zacapa, were explored in 1944 by Leopold Zeissig. 

About 40 pounds of quartz, chiefly grade 1 and of excellent quality, 

was produced from slope wash; the vein that yielded the material 

\vas not found, and the operation was abandoned. 

QUICKSILVER DEPOSITS 

Quicksilver deposits have been reported in Guatemala and El 

Salvador, but the only deposits for which production has been 

recorded are in Honduras. 

HONDURAS 

LOS IZOTES MINE 

Cinnabar deposits at Los Izotes, Departan1ento de Tegucigalpa, 

are owned by the Compaiiia de Cinabrio de Honduras. The property 

covers 5,000 acres on a ridge about 3lh miles long, between the villages 

of Las Quebradas and Jalaca. It can be reached by car from Tegucigalpa by driving 33 miles on the Olancho highway and then westward 

1 mile on a secondary road to the mine. The deposit was explored 

and mined between 1943 and 1945, and 23 flasks of n1ercury was 

produced in 1944 and 1945 from a 4-pipe retort. 

The deposits are in limestone and shaly lilnestone which strike 

N. 40°-70° \V. and dip steeply southwestward. Although no fossils 

have been found in them, they are assigned on the basis .of lithogic 

similarity to the ~:letapan formation of early Late Cretaceous age. 

These rocks are conformably overlain by shale and conglmnerate 
170 MINERAL DEPOSITS OF CENTRAL AMERICA 

which are capped by Tertiary ash and tuff beds a few miles south of 

Jalaca. 

The ore-minerals are cinnabar and a little native mercury and calo,.. 

mel; these are associated with crystalline calcite, which forms veiru> 

and pockets distributed erratically throughout the rock. The ore 

bodies commonly follow fractures. 

The workings consist of many shallow cuts and adits scattered over· 

the limestone belt. Workings 1, on the Victoria claim about 3 miles 

east of J alaca, show small discontinuous veins and pockets of cinnabar· 

in fractured limestone. Much of the ore treated in the retort came 

from these workings. 

One opening at workings 2, 500 feet west of workings 1, is a natural 

limestone cave in the walls of which are small discontinuous veinlets 

of cinnabar and native quicksilver. An adit nearby, in limestone that 

strikes N. 40° 1V. and dips vertica.lly, shows small veinlets and pockets 

of cinnabar, native mercury, and calomel. 

Workings 3 (Victoria) are half a mile east of Jalaca. Cinnabar· 

in fractured limestone here yielded the bulk of the ore treated in the 

retorts. The workings include a lower adit and cut 35 feet long, an 

upper adit, and several shallow cuts. A fault trending northeastward 

separates the two sets of workings. 

The Triunfo workings are 1,700 feet east of J alaca; an opencu:t 

about 50 feet long shows a few discontinuous veins of cinnabar in 

limestone. 

The San Esteban workings, about 1,000 feet northeast of the Triun:fo.-

workings, are in a natural limestone cave that has been enlarged by 

mining. The cave extends about 40 feet from the mouth, and its 

greatest width is about 25 :feet. Small cinnabar veins have been found 

in a vertical shear zone trending N.10° E. 

LA CANADA MINE 

The La Canada quicksilver mine (fig. 15), 31;2 miles west of Jalaca,. 

is owned by Matilde de Castillo and other residents of Tegucigalpa. 

The mine is reported to have been worked on a small scale in colonial 

times, and in 1939 it was reopened by the New York and Honduras 

Rosario Mining Co. No production from the property had been 

recorded. 

The hills west of J alaca consist of shale and limestone of the Meta· 

pan formation that strike northwestward to westward. In the vicinity 

of the mine these rocks dip uniformly northeastward, but elsewhere 

they are folded and are locally contorted. There has been considerable 

solution of the limestone; the old stope was in part a cave, and two. 

other caves were intersected by crosscuts into the hanging-walt 

limestone. 
QUICKSILVER DEPOSITS-HONDURAS 

A' 

3550' 

3525'· 

3500' 

25 0 50 Feet ~~~-L----~~----~ 

5 0 

Base furmshed by New York and Honduras Rosario Mining Co. 

20 Meters 

EXPLANATION 

EJ Cinnabar mineralization 

______t..:o_-

C:~!:ita~~~~ii~a~~fi ~~~;~~d 

Fault, --~···· approximately located, 

showing dip; dotted where 

inferred 

_._!! 

Strike and dip of beds 

Portal 

~\\U//f# Dump 

> > > > 

Inclined workings; chevrons point down 

0 Head of raise or winze 

Geology by Ralph J. Roberts 

171 

Ji'IGURE 15.-Geologic map and section of the La Cafiada quicksilver mine, Departamento de Tegucigalpa, J?-Ionduras. 

The mine workings explore an ore body formed along a contact be~ 

tween shale and limestone. These rocks strike N. 45°-65° W. and dip 

northeastward; the dip above and below the adit level is steep, but in 

some places on the adit level it is nearly flat. The contact is in part 

sharp, but commonly the shale and limestone beds interfinger. The 

limestone, which has been silicified along the contact, is the host rock 
172 MINERAL DEPOSITS OF CENTRAL AMERICA 

of the ore. The contact is sheared and is offset by several small faultsr 

which in large part appear to be post ore, although some pre-ore movement may have taken place on some of them. 

The ore minerals are cinnabar and a little native mercury. The· 

cinnabar in the silicified limestone is associated with iron oxides, pre· 

sumably derived from the oxidation of iron sulfides, and it also occurs 

locally in limestone and .. shale adjacent to the silicified zone. The 

cinnabar is in veins, lenses, and pockets that are distributed erratically 

throughout the silicified rock, which ranges from 3 to 5 feet in thick" 

ness between the portal and the old stope. 

Deposition of the ore bodies appears to have been controlled by the· 

interfingering of shale and limestone, which confined ore-bearing solu· 

tions to the contact zone, and by the local flattening in dip and the 

shearing along the contact. Cross faults which now offset the contact 

may have aided in confining the ore-bearing solutions laterally. 

The ore body mined by the Spaniards extended down the dip for 

50 feet, and in places it was as much as 40 feet wide and 8 feet thick; 

the average width, however, probably did not exceed 20 feet, and the 

average thickness was probably less than 5 feet. It is difficult to estimate the tonnage mined because of backfill and because the stope was 

originally in part a solution cave. It is doubtful whether more than 

300 tons was stoped, and the amount may have been considerably less. 

Four samples collected from the workings gave the following assays : 

Sample Mercury 

no. (percent 1 

81-------------------------~----------------------------------------- 0.09 

82-------------------------------------------------------------·-------- .19 

83---------------------------------------------·----------------------- . 04 

84------------------------------------------------------.. ------------ .003 

A little high-grade ore shows in the winze at the point where sample 

S1 was taken, and also in the crosscut west of the winze and in the old 

stope. PAZ DEPOSITS 

The Paz deposits, including the Coyolito, V enado, and Capitan prospects, are 15 miles northwest of Santa Barbara and are reached by trail 

by way of the village of San Nicholas. The prospects are on the 

south side of the Rio Jicatuyo, at altitudes of 1,400-2,400 feet. The 

property is now owned by Ponciano Paz, Julio Mendieta, and Eduardo 

de Costa Gomez, of San Pedro Sula. No production has been recorded, 

but according to report an English company 1nined several tons of 

ore in the 1880's from the Capitan prospect and shipped it to a mill in 

the Vaile de Chamelec6n. 

The rocks in the area include an older group of limestone and dolomite beds of probable Paleozoic age, which are overlain unconformably by younger limestone, sandstone, conglomerate, and shale that 
QUICKSILVER DEPOSITs-HONDURAS 173 

probably belong to the Metapan :formation and overlying limestone 

unit. The rocks of the older group are complexly :folded, whereas those 

of the younger group have been thrown into broad open :folds. Near 

the shows of quicksilver the rocks of the younger group strike north~ 

eastward and dip northwestward. Two sets of :faults, one set trending 

northeastward and the other northward, cut both groups of rocks. 

The northeastward-trending :faults contain the ore bodies of the 

Coyolito and Capitan prospects. 

The ore bodies in the area are in the rocks of the younger group 

and eonsist of veins that extend along :fault zones, and irregular ore 

bodies that extend along bedding. The ore minerals are native copper, tetrahedrite (probably schwazite, the mercurial variety), cinnabar, cuprite, malachite, and azurite. Of these minerals, only the tetrahedrite and possibly part of the cinnabar are of primary origin; the 

remainder of the cinnabar and the copper minerals were :formed from 

the tetrahedrite during oxidation. Calcite and quartz are the gangue 

minerals. 

COYOLITO PROSPECT 

The Coyolito prospect is in the southwestern part of the area. Two 

shallow pits explore shows of copper along a shear zone that strikes 

N. 50° E. and dips 70° SE. in limestone, conglomerate, and sandstone. 

One of the pits shows a vein as much as 6 in~hes wide composed of 

quartz, azurite, and malachite. A sample taken across the vein gave 

the :following analysis: 0.10 percent mercury, 8.85 percent copper, and 

8.5 ounces of silver to the ton. The other pit, about 40 :feet to the 

northeast of the first, is 10 feet deep. It shows copper carbonates distributed throughout a shear zone about 1 :foot wide ; the material is 

of low grade. 

VENADO PROSPECT 

The V enado prospect is half a mile northeast of the Coyolito prospect. The workings consist of a pit 6 feet wide, 12 feet long, and 6 

:feet deep, in limestone, conglomerate, and sandstone that strike N. 

50° E. and dip 35°-40° NW. The lower 6-18 inches of limestone 

conglomerate is partly replaced by native copper, cuprite, cinnabar, 

malachite, and azurite. Two samples were taken across this layer and 

assayed 0.07 percent mercury, 1.66 percent copper, and 0.7 ounces of 

silver to the ton; and 0.05 percent mercury, 0.47 percent copper, and 

0.3 ounces of silver to the ton. The mineralized bed does not crop 

out beyond the pit, but float :found on the slope indicates that it extends about 300 :feet northeastward. Exploratory work will be needed 

to determine whether the ore is continuous over this distance. 

CAPITAN PROSPECT 

The Capitan prospect, nearly half a mile northeast of the Venado 

deposit, yielded all the ore that has been mined :from the area. The 
17 4 MINERAL DEPOSITS QF CEXTRAL AMERICA 

workings consist of 2 pits, 1 of which was caved in 1943, about 15 feet 

apart in :ferruginous limestone that strikes N. 45° E. and dips 35° NW. 

The accessible pit contained pockets and veinlets of tetrahedrite, cinnabar, malachite, and azurite, which replace the altered limestone. The 

size and shape of the ore body cannot be determined, but it appears 

to be a tabular body trending northeastward. The vein is said to be 

-several feet wide at a depth of 30 feet in the caved pit. A sample taken 

from the open pit assayed 0.90 percent mercury, 1.82 percent copper, 

and 2.8 ounces of silver to the ton. 

GUATEMALA AND EL SALVADOR 

Persistent reports that quicksilver deposits are to be found in Guatenlala have been heard from n1any sources. From time to time Indians 

.come to Guatemala City with small quantities of mercury whose source 

they have refused to reveal, but as the Indians are generally from the. 

volcanic area between Lago de Atithin and Quetzaltenango, the source 

has been presumed to lie in that area. An area of fumarolic activity 

on the volcano Zufiil, about 6 miles south of Quetzaltenango, was 

visited, but no native mercury was seen. Vapor :from some of the 

fumaroles deposited a eoating on eopper that on drying turned gray, 

then bro\vn, and eould be brushed off, but analysis of the. eoating 

showed that it eontained no n1ereury; the material is apparently a 

ehloride whieh attaeked the eopper. The souree of the Indians' mer-

·cnry is therefore still unknown. 

Quieksilver deposits are reported also at several places in El Salvador, but none. of these reports have been confirmed. 

GOLD AND SILVER DEPOSITS 

Although no special effort was made to visit precious-metal deposits, 

the writers were able to gather information on many districts. Some 

of this information was collected by the writers, some was supplied 

by operators in Central America, and some was obtained from published n1aterial. Although the data are by no means complete, they 

will convey a general idea of the ore deposits, their enclosing rocks, 

·and the extent of operations. 

The gold and silver deposits of Central Ameriea may be divided 

into deposits in Tertiary rocks and deposits in pre-Tertiary rocks. 

The deposits in rocks of pre-Tertiary age are related to the intrusive 

activity of early Paleozoic(-~), late Permian, and Mesozoic time. The 

Agna Fria 1nine is an example of the pre-Tertiary deposits. The 

deposits in rocks of Tertiary age are related to intrusive activity 

that took place partly in early Tertiary time, probably beginning in 

the Eocene and continuing into the Miocene and Pliocene. 

The Tertiary gold deposits account for most <?f the production uf 

Central American gold and silver. They occur principally in eastern 
GOLD .AND SILVER DEPOSITS-HONDURAS 175 

El Salvador, western Guatemala, central Honduras, and northern 

~-icaragua. These districts are all in areas of Tertiary volcanism 

and are included in an eastward-trending chain of volcanoes, the 

F'acific coastal belt, and an older eastward-trending chain from which 

the widespread lava flows and pyroclastic rocks that mantle the middle part of. Central America originated. The gold deposits of Costa 

Hica and Panama are separated fron1 this belt by the Nicaraguan 

lowland. 

PRODUCTION 

The gold and silver production of Central An1erica has passed 

through several stages. The first stage, the colonial period, was 

rnarked by production from a large number of properties, both placer 

and lode. Production was on a small .scale, primitive methods were 

used, and the recovery was probably low; however, for nearly 300· 

years the annual production may have been worth from a few thousand to several hundred thousand dollars a year. The second stage, 

1821-80, was characterized by erratic production for which few data 

are available, but it is inferred from available data that the value of 

the production during the 1860's, the period of greatest activity, averaged about $600,000 a year. 

During the early part of the period from 1880 to 1933 the ores 

ntined were of high grade, but the percentage of recovery of metals 

from the ores was small. Recovery was improved by the introduction 

of the cyanide process, but the grade of the ore declined gradually 

during the latter part of the period as the bonanza shoots were exhausted and leaner portions of the veins were mined. Greater mining 

and metallurgical efficiency permitted treatment of lower grade ores, 

and some old mines were reopened. The increase in production was 

nwst notable in Nicaragua, where the value of the annual production 

increased from about $500,000 in 1936 to more than $8 million in 1942. 

HONDURAS 

EL ROSARIO MINE 

The El Rosario mine is on the east flank of the Sierra de Santa 

Ijucia, about 16 miles northeast of Tegucigalpa, Departamento de 

'Tegucigalpa, and at an altitude of 5,500 feet. A road passable the 

year round extends from Tegucigalpa to the mine. The mine is owned 

by the New York and Honduras Rosario Mining Co. and was in 

nearly continuous production from 1882 to 1954 (Leggett, 1889; Eng. 

and Min. Jour., 1920, p. 1163; Newberry, 1888; Matheson, 1942, p.112; 

l~ng. and Min. Jour., 1954). The value of the production from this 

n1ine, chiefly silver, totals about $75 million. The long period of 

operation and the high productivity make this one of the outstanding 

silver mines of the world. The table below gives its production during 

recent years. 
176 MINERAL DEPOSITS OF CENTRAL AMERICA 

Gold and silver produced from the El Rosario mine, Honduras, 1935-1,.9 1 

Year Au (ounces) Ag (ounces) Value (dollars) 

1935________________________________ 12,236 

1936________________________________ 17,878 

1937________________________________ 21,717 

1938________________________________ 19,916 

1939________________________________ 17,800 

1940 __ ------------------------------ 23, 173 1941________________________________ 22,.828 

1942________________________________ 22,089 

1943________________________________ 18, 221 

1944________________________________ 19, 774 

1945________________________________ 17, 078 

1946________________________________ 12,093 

194 7--- - - - ---- - - - - - - - - - - - - - --- - - - - - - 11, 928 1948________________________________ 13, 305 

1949 ________________________________ -------~--

1 Mines Register, 1937, 1940, 1942, 1946. 2 Annual report of New York and Honduras Rosario Mining Co. 

2, 646,411 

3, 104, 174 

3, 574, 116 

3,335,067 

4, 118, 887 

3,889,164 

3,448,667 

3,478, 831 

3, 168, 523 

3, 115, 351 

3, 003, 494 

2, 682,910 

2,403,500 

2, 389,353 

2,276,698 

2,019,313 

1, 953, 690 

2, 113, 645 

2,053,104 

2,205,451 

2, 175, 173 

2,019,045 

2, 187, 817 

2,056,136 

2,093,990 

2, 383, 020 2 2, 826, 870 

2,168,200 

2, 354, 132 

2, 329,359 

The workings consist of about 150 miles of underground workings 

over a vertical range of 1,400 feet. An average of 200,000 tons of ore 

containing 16-17 ounces of silver and about 0.08 ounce of gold to the 

ton was treated annually. 

The oldest rocks in the mine area are gray shale, siltstone, and sandstone of Jurassic age (Knowlton, 1918) 3,000 feet in thickness (Carpenter, 1954, p. 25; Newberry, 1888). These rocks are overlain by siltstone, sandstone, limestone, and andesitic tuffs and breccias of Early 

C:vetaceous age that are probably correlative in part with the Meta pan 

formation. All these rocks have been cut by andesitic, dacitic, and 

granodioritic plugs and dikes. The silver-bearing quartz veins are in 

the dacitic intrusive rocks and form a complex pattern; the predominant systems trend roughly N. 70° W. Of the 85 known veins, 

46 have yielded the major part of the production. Younger sedimentary, volcanic, and pyroclastic rocks of later Cretaceous and Tertiary 

age rest on the older rocks. 

The ore minerals are pyrite, sphalerite, galena, chalcopyrite, stephanite, argentite, pyrargyrite, native silver, and electrum. Rhodonite 

is found in some of the ore. Most of the ore shoots are rich in silver, 

but some veins, including the Santa Fe and Colonia, contain ore shoots 

with a high gold content. 

Most of the veins are less than 4 feet thick, are persistent, and for 

the most part are uniformly mineralized. As many as 35 veins are 

stoped at the same time, although generally 4 or 5 veins furnish the 

bulk of the ore mined. 

AGUA FRIA MINE 

The Agua Frfa mine is 5 miles north of Danll, in the Departamento 

de El Paraiso, at an altitude of 3,200 feet in the Cordillera de Villa 
GOLD AND SILVER DEPOSITS-HONDURAS 177 

"S::tnta. An all-weather road extends from Tegucigalpa to the mine, 

and planes can land at an airport 3 miles north of the mine. The deposit was discovered in 1915, and for' several years the oxidized ore 

from the upper part of the vein was mined and concentrated in an 

arrastre by the Gamero family of DanH. In 1935 a combination cy~ ... 

nide and flotation mill of 120 tons daily capacity was put into operation by Earl P. ·Halliburton, of Los Angeles. The deposit was mined 

until June 1943; its production is shown in the table below. 

Gold produced from the Agua Fria mine, Honduras, 1935-43 t 

Year Ounces -Value (dollars) 

1935------------------------------------------ 3, 949 137, 384 

1936-- ---------------------------------------- 9, 824 343, 463 

1937 __ --------------------------------------- 12,005 419;,108 1938__________________________________________ 10,252 357,938 

1939------------------------------~----------- -------~---- ----------~- 1940,_----------------------------------------- 34,822 1, 215,705 

1941-----------~--~~-------------------------- ------------------------ 1942- - - - - - - - - - - - - - - ~ - - - - - - - - - - - - - - - - - - - - - - - - - - 6, 994 ' 244, 196 

1943 2- - - - - - - - - - - - - - - - - - _; - - - - - - - - - - - - - - - - - - - - - - 2, 640 92, 161 

1 Figures furnished by the Cia. Agua Frta. 3 To end of June, when mining ceased. 

The rocks in the area are alternating thin-bedded shales and massive gray quartzites striking N. 30°-45° E. and dipping 30°-50° NW.; 

they form the northwestern limb of a syncline that pitches southwestward. These rocks have a thickness of more than 4,000 feet. Just 

south of the mine they are intruded by a hornblende-biotite granodiorite stock about 2,000 feet in diameter. Porphyry dikes related to 

the granodiorite cut the shale and quartzite in the mine area. The 

mine is developed by adit levels in the upper part and by a shaft 

370 feet deep with a 300-foot winze offset on the 400-foot level. The 

maximum vertical range developed is 760 feet. 

The Agua Fria quartz vein, which cuts the shale and quartzite, 

strikes N. 25° E. and dips 70° NW. in the upper part of the workings, 

but downward the dip gradually flattens to 50° NW. The ore minerals 

are arsenopyrite, chalcopyrite, and pyrite, with minor quantities of 

pyrrhotite, sphalerite, galena, and marcasite; meneghinite commonly 

lines vugs in the ore. The gold is associated principally with the 

arsenopyrite. 

The vein ranges in thickness from a foot to more than 6 feet. The 

ore shoot is in the form of a right triangle whose rig.ht angle is in the 

upper northern end of the vein and whose hypotenuse forms the bottom boundary of the ore. The ore shoot is 1,400 feet long in the upper 

workings and gradually shortens to 200 feet on the 600-foot level. On 

the north it is terminated by a bedding-plane fault filled with gouge 
178 MINERAL DEPOSITS OF CENTRAL AMERICA 

derived from comminuted shale. This fault was premineral and 1nay 

have aided in the localization of the ore shoot. 

The ore shoot contains three zones : the ·lowest, arsenopyrite, is at 

the south end of the shoot; the middle part is arsenopyrite, chal- . 

copyrite, and pyrite; and the upper part is chalcopyrite and pyrite 

with minor amounts of arsenopyrite. The ore mined, about 200,000 

tons, contained an average of 0.55 ounces of gold and 0.70 ounces of 

silver to the ton and 0.75 percent copper. 

Operatiops ceased in 1943 because all the commercial ore in sight 

had been stoped. Further exploratory work was continued during 

1944 and 1945, and although low-grade ore was found in nearby veins, 

not enough tonnage had been developed to warrant reopening the mill. 

SAN ANDRES MINE 

The San Andres mine is about 12 miles southwest of Santa Rosa de 

Copan, in the Departamento de Copan, at an altitude of about 3,500 

feet on the west slope of Cerro de Magdalena. The mine was worked 

on a small scale by an English company in the 1920's, and production was correspondingly small. The property was formerly owned 

by Rudolf N ater, Manuel Bueso, and their associates, but in 1946 it 

was sold to the W. H. Gould Co., of San Francisco, Calif. A mill 

was installed in 1947 and has operated since then. 

The ore deposit consists of gold quartz veins in rhyolite, which is 

in fault contact with mica schist. Calcite is locally abundant in the· 

veins. The mineralized zone is 10-50 feet wide, 800 feet long, and 

has been developed for 300 feet down the dip. Pyrite is found locally 

in the wall rock at depth. 

ANDERSON AND REY DEL ORO MINES 

The Anderson and Rey del Oro mines, 7 miles southeast of Juticalpa 

in the Departamento de Olancho, contain small quartz veins in phyllite 

and quartzite. The veins are 2-3 feet wide and are exposed for several hundred feet along the strike. The gold in the veins is largely 

free milling, although associated with pyrite. The ore shoots are· 

commonly small, containing from several hundred to a :few thousand 

tons apiece. 

MANGULILE MINES 

The veins at Mangulile, about 45 miles northwest of J uticalpa, are 

similar in mineralogy to the Anderson and Rey del Oro veins but are 

narrower. Although some of them have been worked on a small scale, 

mining is difficult because of the er~aHc distribution of the gold in 

the quartz. · 

OPOTECA MINE 

The Opoteca mine is 10 miles north of Comayagua. It was exploited in colonial ti1nes by the Spaniards, was explored from 1918· 
GOLD AND SILVER DEPOSITS-HONDURAS 179 

to 1921 by the West End Consolidated Mining Co. (Mines Handbook, 

1925, p. 2267), and in 1946 was under option to Panaminas, Inc. The 

rocks in the area consist of Cretaceous limestone, which has been 

broken by steeply dipping fractures. Argentiferous galena veins replace the limestone along the fractures. The ore is reported to contain 2-40 ounces of silver to the ton. 

OTHER DEPOSITS IN NORTHWESTERN HONDURAS 

Other silver deposits near Comayagua, Y oro, and Mangulile consist 

of cupriferous veins that cut phyllite and limestone. Some of these 

veins have been exploited on a small scale, but none seem likely to 

become large producers. Silver occurs also in galena-sphalerite-quartz 

veins near Cedros and at Pino Alto, near the Agua Fria mine. 

Other properties and prospects are situated in the headwaters of 

the Rio Chamelec6n near Macuelizo. Much exploratory work has 

been done on smne of the veins, but none has yielded a profit. 

Prospects in the headwaters of the Rio Chancaya west of Y oro, 

Departamento de Y oro, in the Sierra N ombre de Dios south of Tela 

and La Ceiba, near Cedros and Minas del Oro in the Departamento 

de Cedros, and in the Sierra el Chile east of Talanga, Departamento 

de El Paraiso, have been explored intermittently since Spanish colonial 

times. 

SAN FELIX MINE 

The San Felix mine consists of several small gold and silver-bearing 

quartz veins about 6 miles north of Langue, Departamento de Vaile. 

The veins cut andesite and rhyolite tuff. Smne of them were exploited 

in the early 1920's, but because the ore remaining is of low grade 

there has been no re~ent activity in the area. 

LA VICTORINA MINE 

The La Victorina mine is 18 miles northeast of Langue. This 

property was exploited from 1910 to 1920, when 50,000 tons of ore, 

with an average value of $15 a ton, is estimated to have been milled. 

The ore body is a quartz vein trending northwestward and dipping 

60°-70° NE. The ore shoot mined was 600 feet long and extended 

for 300 feet down the dip. 

CONCHAGUA MINE 

The Conchagua mine is 10 miles southeast of El Parafso, in the 

Departamento de El Paraiso. The property was worked intermittently 

during the 1930's, and the ore was treated in a mill of 15-20 tons 

daily capacity which was equipped with amalgamation plates and 

tables. The deposits are narrow quartz veins containing gold that 

strike N. 65° E. and dip 70° NW. and that fill fractures in phyHite 

and limestone. The gold is reported to be coarsely granular. 
180 MINERAL DEPOSITS OF CENTRAL AMERICA 

LA ALHAMBRA MINE 

The La Alhambra deposit is 30 miles northeast of DanH, in the 

eastern part of the Villa Santa Cordillera. Quartz veins in phyllite 

and limestone have been exploited on a small scale, but the property is 

now inactive. Small gold quartz veins are known also in the Batea 

district nearby. 

SANTA LUCiA AND VALLE DE ANGELES MINES 

The veins of the Santa Lucia and Valle de Angeles n1ines, a few 

miles south of the Rosario mine, are similar in mineralogy to the 

Rosario veins, but they cut rocks of the Meta pan formation. Although 

some are of high grade, the veins are small and have been exploited 

only on a small scale. 

The principal vein is the Las Animas, which was first opened by 

the Los Angeles Mining and Smelting Co. in 1888. The property 

passed to don Santo Soto in 1897 and was operated at intervals to 

1927, when the mill burned. Paul Bundy estimated that possibly 3,000 

tons had been mined from the vein, which averages about 31;2 feet 

in width, strikes northeastward, and dips 24 ° SE. The Socorro vein 

nearby strikes N. 60° E. and dips 16° SE. It was first opened in 

1882 and is reported to have produced a small amount. 

MONTANITA AND SAN ANTONIO DE ORIENTE DEPOSITS 

Veins in the Monta:fiita area, about 7 miles east of Tegucigalpa, and 

in the San Antonio de Oriente area nearby, were exploited by the 

Spaniards before 1900, but both were abandoned in 1944. Pyritesphalerite-galena-quartz veins in the San Antonio area are in gently 

dipping rhyolite tuffs and lavas ; some of the ore follows the bedding 

in the rhyolite. The veins in the Montaiiita area are in rocks of the 

Metapan formation. 

YUSCARAN DEPOSITS 

The Y usearan deposits are 30 1niles east of Tegucigalpa, in the Departamento de El Paraiso, on the eastern flank of Cerro Montserrn t. 

The area was. a-ctively worked in colonial times and also between 1850 

and 1900. It is said to have yielded in all about $6 million worth of 

silver and gold, which came chiefly from the Veta Grande mine. In 

1919 control of the area was acquired by the American and Honduras 

Mines Corp., but the mines were not exploited. In 1945 the New 

York and Honduras Rosario Mining Co. purchased the property. 

The rocks in the area are andesites overlain by rhyolite and rhyolite tuffs. These rocks have been broken by 2 major post-ore northward-trending faults, half a mile apart, which divide the area into 3 

blocks. The eastern block contains the Capiro, Guayabillas, and 

other veins; the middle block contains the Santa Elena, Mercedes, 

Veta Grande, N ovillo, and Santa Fortuna veins; and the western block 
GOLD AND SILVER DEPOSITS-HONDURAS 181 

contains the Santa Margarita, San Isidro-Santa Gertrudis, and San 

Juan veins. 

The quartz veins of all three blocks trend eastward and dip steeply 

northward. The Guayabillas, Santa Elena, and Santa Margarita 

veins are valuable principally for gold, but contain· small quantities of 

pyrite, sphalerite, and galena. The rest of the veins contain a good 

deal of silver as well as gold, with higher percentages of the sulfides. 

SABANA GRANDE MINES 

The Sabana Grande silver-gold mines, in the Departamento de 

Tegucigalpa, were operated between 1919 and 1928 by the New York 

and Honduras Rosario Mining Co. The mines were inactive between 

1928 and 1951 but were being reopened in 1951 by the company. The 

deposits consist of several quartz veins, which contain pyrite, sphalerite, galena, silver sulfides, and gold. The rocks in the area are andesitic and rhyolitic lavas and tuffs of Tertiary age. 

EL PORVENIR MINE 

The El P6rvenir gold mine is near the Honduras-El Salvador border, about 12 miles north of the village of Goascoran. The mine was 

exploited between 1880 and 1910 by English and American groups, but 

the production is not known. Attempts to reopen the mine in the late 

1930's were not successful. At present, a few people living nearby 

crush surface ore and pan it for gold in a nearby stream. The ore 

bodies are short narrow quartz veins in andesite and in rhyolite tuffs. 

The ore shoots are said to have yielded bonanza pockets containing 

free gold. 

EL TRANSITO MINE 

The El Transito mine, 10 miles southeast of Goascoran, has been 

intermittently exploited and has yielded only a small amount of gold. 

The property was purchased in 1944 by the American Smelting and 

Refining Co. and was being reopened in June 1944. The deposit is a 

quartz vein, said to be 20-30 feet wide, containing pyrite and free 

gold. 

SAN MARTIN DEPOSITS 

The San Martin deposits are 10 miles north of the Inter-American 

Highway, near the town of San Martin in the Departamento de, 

Choluteca. Some of the veins were exploited in the 1880's by a French 

company but are now abandoned. The veins cut andesite and are developed by adit levels and shafts. 

EL CORPUS DEPOSITS 

The El Corpus deposits are 10 miles southeast of Choluteca, on the 

Inter-American Highway. They were exploited by British and Amer-
182 MINERAL DEPOSITS OF CENTRAL AMERICA 

ican groups during the last part of the 19th century but were abandoned in 1944. 

TATUMBLA MINE 

Veins of gold ore near Tatumbla, 10 miles southeast of Tegucigalpa, 

were explored by t:he Agua Fria Co. in 1938 and by Herederos Santos 

Soto in 1941. Quartz stockworks in rhyolite tuff contain pyrite and 

gold, but the gold occurs in such small quantities that the ore is of 

low grade. 

EL MOCHITO MINE 

The El Mochito mine is 8 miles southwest of J aral, a village on 

Lago de Yojoa, and can be reached by road from the PotrerillosTegucigalpa highway. The mine is at an altitude of 3,200 feet. The 

property was purchased in 1943 by the New York and Hondura::, 

Rosario Mining Co., which carried on exploratory and development 

work until1949 when a 150-ton mill was installed and put into operation. In 1949, 36,917 tons having a gross value of $812,438 was milled; 

the ore yielded 1,083,560 ounces of silver. The ore also contained 

0.02 ounces of gold a ton and 1.18 percent lead. The concentrates were 

shipped to El Paso, Tex. 

The rocks in the area are interbedded sandstone, shale, and limestone of the Meta pan formation. The ore bodies, which crop out along 

a fracture zone that trends N. 20° E. and dips steeply northwestward 

in the limestone, can be followed for more than 1,000 feet. They contain argentiferous galena, native silver, sphalerite, and chalcopyrite~ 

in a gangue of sche:fferite (a manganese pyroxene), rhodochrosite, 

and calcite. The sche:fferite is altered to manganese oxides at the 

surface. 

QUITAGANA MINE 

The Quitagana mine is near El Corral in the Departamento de 

Gracias. The property was optioned in 1951 by the New York and 

Honduras Rosario Mining Co., and it is reported that exploratory 

work was being carried on in 1952. The ore is said to be zinc-coppersilver bodies in fissures and along bedding. 

PLACER DEPOSITS 

The placer mines of eastern and northern Honduras were the source 

of most of the placer gold being produced in Central America in 1944. 

These placers have been worked intermittently from the 16th century 

to the present. Although companies installed mechanized equipment 

to work the placers during the late 1940's, none of the operations has 

been successful. 

RiO GUAYAPE AND RiO JALAN PLACERS 

The valleys of the Rio Guayape and Rio J alan (Wells, 1857) are 

in the rugged mountains of the Departamentos de Tegucigalpa, El 
GOLD AND SILVER DEPOSITS-HONDURAS 183 

Paraiso, and Olancho. Both rivers flow southeastward :for 50. miles, 

then turn northeastward and join near J uticalpa; :from here to the 

mouth of the Rio Guayambre, the system comprising both rivers is 

called the Rio Guayape; downstream, it is called the Rio Patuca. 

The gold placers along the Rio Guayape occur betweep. .Paso de 

Compadre, east of Campamento, and the junction of the Rio Guayape 

and Rio J ahin at Juticalpa (pl. 1; also see Haley, 1941, p. 36). For 

20 miles below Paso de Compadre the gold-bearing gravels are thin 

and are confined to a narrow stream valley, but farther downstream 

they become thicker, and below El Retiro they are more than 40 feet 

thick. Some tributary streams near E,l Rusio, Ocotal, and El Retiro 

also contain gold-bearing gravels. Placers are found along the Rio 

J alan fron1 El Rosario to Teupacenti. In this segment the river is 

largely confined to a narrow gorge, and the placer gravels are consequently narrow and thin. Downstrea:m from Teupacenti, where the 

valley broadens to a mile or more in width, the gold-bearing gravels 

interfinger with barren gravels from tributary streams. The Rio 

Frio and La Vijao tributaries, 20 miles downstream from Teupacenti, 

also contain local placers. 

The gold placer deposits have been derived from myriad small 

quartz veins that cut the phyllite and quarzite of central and eastern 

Honduras. Gold was concentrated in gravels during several cycles of 

erosion within Tertiary time. ·Although the details have not been 

worked out, some of the events during the Tertiary that influenced 

concentration of the gold can be described. 

In early middle Tertiary time, prior to the volcanic eruptions, central and eastern Honduras was an area of low relief. Streams flowing over this area were probably adjusted to the structures, and some 

flowed eastward and some westward.. When the surfaces became 

covered with lavas and pyroclastic rocks in later middle Tertiary 

time, consequent streams on the surface of the volcanic rocks flowed 

southeastward. Regional uplift probably accompanied the volcanism, 

and the streams cut downward through the volcanic rocks, again encountering the eastward-trending phyllite and quartzite beds beneath. 

The streams maintained their southeastward courses on these rocks, 

except where their courses were changed by capture. 

The gold was probably first concentrated during the middle Tertiary erosion period, in gravels of the streams flowing eastward and 

westward. Then, after the period of volcanism, streams cut d.own 

through the older gravels and reconcentrated the gold in the presep.t 

valleys, chiefly in those of the southeastward·flowing streams. · 

Drilling has shown that the Rio Guayape and Rio Jalan gold-bearing gravels are erratically distributed throughout the alluvium i~ the 

388364~57----13 
184 MINERAL DEPOSITS OF CENTRAL AMERICA 

flood plains of these rivers. The most successful operators have become skilled at finding pockets of higher grade material, yet even 

under such circumstances the average daily earnings are generally 

small. It is doubtful whether large-scale operations would be profitable with gold worth $35 an ounce. 

OTHER PLACERS 

Other plac.ers are reported in the upper parts of the valleys of 

the Rio Sico and Rio Paulaya in northeastern Honduras, and also in 

the tributaries of the Rio Patuca above Guampu. Gold is also said 

to have been found in the upper part of the Rio Segovia basin, along 

the border between Honduras and Nicaragua. Small placers occur 

near Minas de Oro in central Honduras, near San Martin and Langue 

in southern Honduras, and near Macuelizo in northern Honduras. 

COSTA RICA 

Gold production in Costa Rica has decreased in recent years, although deposits are still actively mined in many districts. The 

mines are in a belt 66 miles long that extends along the west slope 

of the Cordillera Central of Costa Rica. The Ferrocarr:il al Pacifico 

runs south of the belt to Puntarenas, passing close to some of the mines. 

The other mines can be reached by roads connecting with the railroad 

or with docks on the Golfo de Nicoya. 

In southern Costa Rica, as in Panama, the Indians began in prehistoric days to seek gold for ornaments, and placer mining has probably been continuous fr01n the colonial period up to the present day . 

.4.GU.4.C.4.TE DISTRICT 

The Aguacate district (Huttle, 1942; Bennet, 1939; Malozemoff, 

1942) on Cerro del Aguacate, about 30 miles west of San Jose between 

San Ram·6n and San Mateo, has been producing intermittently since 

gold was discovered there in 1822. Operations were on a small scale 

until 1907, when several properties were combined as the Aguacate 

Mines, Inc. From 1907 to 1927 there was little systematic exploration. Two mines were active in the district in 1945; the Compaiiia 

Aurifera N acional was treating 40 tons of ore daily from the Oreamuno-Castro vein, and Srs. J uchem and Sanford were treating 40 

tons of ore daily from the Union vein. The Union vein, which is 

about 2,000 feet northwest of the Sacrafamilia vein, has been explored 

for 2,000 feet along the strike and over a vertical range of 1,000 feet 

(Malozemoff, 1942). 

.4.B.4.NG.4.RES DISTRICT 

The Abangares district is 4 miles northeast of Las Juntas, in the 

Provincia de Guanacaste. Mining began in this district in the 1880's, 
GOLD AND SILVER DEPOSITS-cOSTA RICA 185 

but it was not until1892, when Minor C. Keith acquired the San Rafael 

mine, that large-scale operations began. Keith later purchased the 

Tres Hermanos and Boston mines and operated all of them together 

under the name of Costa Rica Union Mines, Inc. Between 1892 and 

1928 these mines are reported to have produced about $33 million in 

gold. After 1928 they were leased to individuals, and the ore mined 

was treated by the mill on a custom basis. In 1942 the company was 

reorganized and was later optioned to the Panaminas Co. of New 

York, a subsidiary of Ventures, Ltd. 

The ore deposits are quartz veins in andesite flows. The veins strike 

N. 30° E. and dip steeply southeastward. They are generally 5-8 feet 

wide, although at some intersections with branch veins they are as 

much as 20 feet wide. They contain sparsely distributed sulfides, including pyrite, chalcopyrite, sphalerite, galena, and, locally, stibnite. 

The Tres Hermanos vein can be traced on the surface for 6,000 feet 

and has been mined for 3,000 feet and to a depth of 500 feet. The San 

Rafael vein, a branch of the San Martin vein, contained several rich 

bonanzas; it was mined for 1,000 feet along its length and to a depth of 

400 feet. MIRAMAR AND ESP4,RTA DISTRICTS 

In the Miramar and Esparta districts, which lie between the 

Aguacate and Abangares districts, many veins have been exploited 

intermittently. In the late 1930's the Albert Rudin Co. operated the 

Santa Elena, Trinidad, Bonanza, and El Encanto mines, which yielded 

150 tons of milling ore daily. 

The rocks in the Aguacate area are andesitic lavas and pyroclastic 

rocks which form part of the Cordillera Central of Costa Rica. 

Locally these rocks have been intruded by basalt. Three principal 

quartz veins-the Oreamuno-Castro, the Sacrafamilia, and the 

Union-have been exploited in the district. These veins are nearly 

parallel, strike N. 30° E., and dip steeply northwestward. 

The Oreamuno-Castro vein has been worked for a length of 3,000 

feet and over a vertical range of 800 feet. It is 3-20 feet wide and 

contains narrow ore shoots that plunge steeply northward. The gold 

in the ore shoots in the southwestern part of the vein is associated with 

pyrite, arsenopyrite, and a minor amount of realgar. The ore shoots 

in the northeastern parts of the vein are smaller and of lower grade; 

the gold in them is associated with rhodonite, pyrite, sphalerite, chalcopyrite, and galena. Pockets of manganese oxide that are found in 

the oxidized zone were presumably derived from oxidation of the 

rhodonite. The Sacrafamilia vein, 1,500 feet west of the OreamunoCastro vein~ contains sparse sulfides. Only a few ore shoots have been 

discovered in this vein. 
186 MINERAL DEPOSITS OF CENTRAL AMERICA 

The San Gerardo mine south of San Ramon, the Llano Brenes mine 

north of the Aguacate area, and the Bella Vista and Montezuma mines 

north of ~iiraniar each produced 10-40 tons a day, although production 

has been intermittent. Most of the veins are narrow and contain 

erratically distributed ore shoots. 

PENINSULA DE OSA AREA 

The most important placer area is on the northern slope of the 

Peninsula de Osa in southern Costa Rica (Malozemoff, 1942). Work 

is confined to the valleys of the Rio Madrigal, Rfo Nuevo, and Rio 

Tigre, which drain into the Golfo Dulce. In 1944, it is reported, 400-

600 men were employed inprimitive operations on the streams; how 

much they mined is not known. 

NICARAGUA 

Nicaragua is the principal gold-producing country of Central 

America. The 8 largest properties in production yielded over 110,000 

tons of ore monthly in 1945, and this tonnage has probably increased 

since that time. During World War II the production dropped but 

little. It seems likely that many other properties will be tested to 

determine whether they can be· operated profitably under postwar 

conditions. 

Transportation is the principal problem in development of mines 

in Nicaragua. Good roads and railroads are found only in the western 

part of the country. The Inter-American Highway and feeder roads, 

which were completed in 1943, did much to improve transportation, 

but for the most part central and eastern Nicaragua are without roads 

and can be reached only by poor trails. Airports are scattered over 

the country, but as yet only high-value freight can be transported by 

airplane; the bulk of the material to be moved must be handled by slow, 

laborious methods. LA LUZ MINE 

The La Luz mine is in the Departamento de Zelaya, 95 miles westsouthwest of Puerto Cabezas at the village of Siuna (Scobey, 1920; 

Garbrecht, 1920). The deposit was discovered by Spanish prospectors 

~nd was put into operation on a small scale in 1896 by Jose Aramburli. 

In 1919 the property was incorporated as the La Luz and Los Angeles 

Mining Co. F~om 1901 to 1926 the value of the recorded production 

amounted to about $5. million, which was obtained from 700,000 tons 

of ore {Mines .Handbook, 1926, p. 2041). The property was partly 

dM.troyed by re.volutionists in 1928 but was subsequently rebuilt; in 

l938 it was acquired by Y entures, Ltd. and renamed La Luz Mines, 

Ltd. The mill was enlarged in 1945 and changed to a combination 
GOLD AND SILVER DEPOSITS-NICARAGUA~ 187 

flotation and cyanidation plant treating 1,800 tons daily. ·The production :from 1939 to 1945 is shown in the table below. 

Gold and silver produced from the La Luz mine,-Nicaragua, 1939-4-5.1 

Year Tons milled Au (ounces) Ag (ounces~ Valu~ (dollars) 

1939 _______________ 10,098 1, 124 3Eh 39,'259. 65 1940 _______________ 171,551 35,701 13,698 1, 249; 482; 31 1941 _______________ 367, 135 73,033 34,079 2,553,875. 00 1942 _______________ 436, 125 79,768 38,866 2,792,257. 73 1943 _______________ 369,099 75,965 32,759 2, 659,. 900. 08 1944 _______________ 416,024 67,994 27, 168 2,377,878.46 1945 _______________ 425,038 71,856 22, 187 2, 513, ·025. 44 

t Figures furnished by La Luz Mines Ltd., Siuna, Nicaragua. · 

The rocks .in the area are shale and limestone, graywac~e, slate, and 

lavas which probably belong to the Metapan :formation o:f Cretaceous 

age; all have been intruded by andesite (Graham A. Nelso_n, 'Yritten 

communication) . The ore occurs in the closely :folded sedimeJ.?.tary 

rocks in a zone 300-400 :feet wide and about 2,000 :feet long, on the 

:foqtwall side o:f a wide andesite dike. Small quantities of.pyrite, chalcopyrite, galena, and sphalerite occur with the gold. 

Underground exploration shows that the ore extends to a depth of 

at least 825 feet. Until 1944 the ore was mined mainly from an ·open 

pit, but since then much o:f it has been stoped :from underground 

workings. In 1949 about 500 tons daily was mined from the open plt 

and 800 tons daily from underground workings. 

Supplies :for the mine are brought upstream to Alamicamba, on the 

Rio Prinzapolka, .in shallow-draft •barges towed by launches, then 

flown 42 miles west to the mine. 

PIS PIS DISTRICT 

····The Pis Pis district is about 75 miles west of Puerto Cabezas in the 

Departamento de Zelaya, 15 miles north of the La Luz mine. Gold 

mines have been exploited in the Pis Pis district since 1880, .and up to 

1920 the district had produced about $12 million worth of gold. 

Because no roads ·or railways reach the district from eith{ll' coast, 

transportation of supplies has always been a major problem. Before 

1920 barges carried most of the freight .·up the Rio Prinzapolka and 

the. Rio Bambana from--the east coast. However, sincel935 #eight 

~s been brought in pr~ncipa:Ily by air.-- · · - _ . . ~ 

- The mine8 'in the- Pis Pis district occur in a belt that is about -12 

~p.iles long and as much as, 3 miles wid~. The mines a-re grouped in 

three· areas in the belt: the Neptune-Eden (Bonanza) group on the 

northeast, the Pioneer:-Lone Star group in the middle, and the 

Constancia group on the southwest. 

·~ -·Y -:~ 
188 MINERAL DEPOSITS OF CENTRAL AMERICA 

The mines were separately owned and operated prior to 1922. A. 

150-ton mill was installed at the Bonanza mine in 1923; ore from the 

Bonanza, Pioneer-Lone Star, and Constancia groups was treated in 

this mill. The Eden mine (Garbrecht, 1920) first began operation in 

the district in 1914; a 140-ton mill was put into operation in 1918, and 

production continued until1922. Ore from the Eden, Culebra, Hidden Treasure, Philadelphia, and Morning Star veins was treated in 

this mill. 

The mines were closed during the revolution in the mid-1920's. In 

1934 they were acquired by the American S1nelting and Refining Co., 

the New York and Honduras Rosario Mining Co., and others, and the 

Neptune Mining Co. was formed. A. new mill of 500 tons daily capacity was built .in 1938; in 1944 its capacity was increased to 800 tons. 

The Bonanza vein had the highest production in the past, but in 

1951 the principal producing veins were the Eden, Hidden Treasure, 

Neptune, Venus no. 2, Corral, Culebra, and Tesoro veins. None of 

the veins in the Constancia area were being stoped in 1951. The production from 1938 to 1950 is given in the table below. 

Gold and 8ilver production of the Neptune Mining Co., Nicaragua, 1938-50 l 

Year Tons milled Au (ounces) Ag (ounces) 

1938 ____ -------------------------- ------------ ------------ ------------ 1939 ______________________________ ------------ 35, 130 81, 873 

1940-------------- - -------------- - ------ - - - - - - ------------ ------------ 1941______________________________ 211, 600 49, 518 96, 319 

1942______________________________ 263, 280 65, 508 90, 930 

1943______________________________ 238,735 59,098 94,681 

1944______________________________ 228, 533 52, 755 97, 328 

1945______________________________ 233,669 50,730 95,877 

1946______________________________ 237, 502 55, 916 85, 908 

1947______________________________ 232,463 57,476 86,295 

1948______________________________ 251,767 61,034 78,792 

1949______________________________ 252, 560 66, 112 83, 713 

1950______________________________ 260, 129 71, 961 76, 122 

t Data from annual reports of the Neptune Gold Mining Co., Nicaragua. 

The ore bodies are in quartz veins that cut andesite, which probably 

includes both extrusive and intrusive facies. The veins belong to 2 

sets: most of them strike northeastward, dip steeply, and follow faults 

of moderate to large displacement; 2 veins strike northwestward and 

follow faults of small displacement. The veins range in width fron1 

a few feet to 30 feet and have been traced for as much as 6,000 feet 

along the strike. 

The ore minerals are pyrite, galena, chalcopyrite, and hematite. 

Generally the sulfides are sparse and occur in small pods or along 

narrow fractures in the veins. The gangue minerals are principally 

quartz with a little carbonate, rhodonite, and rhodochrosite. The 

tenor of the ore averages about 0.29 ounces of gold per ton. 
GOLD AND SILVER DEPOSITS-NICARAGUA 189 

CHONT ALES DISTRICT 

The Chontales district is in south-central Nicaragua, about 75 miles 

east of Managua. Mining in this district began about 1860. Goldquartz veins occur in 2 areas about 5 miles apart: the Santo Domingo 

area, with the San Gregorio and J a bali mines, and the La Libertad 

area, with the San Juan and Babilonia mines. In 1942 about 5,500 

tons of gold ore was being mined each month at the J abali mine 

(Kettel, 1942, p. 114, 115). 

Belt ( 1888) described the veins of the Santo Domingo area as being 

eastward-trending quartz veins of steep dip; they are 1-20 feet wide, 

their average width being about 7 feet. The veins extend along the 

strike for as much as 4,000 feet and are closely spaced in a belt a 

mile wide. The ore shoots are distributed erratically. The gold is 

generally associated with pyrite, chalcopyrite, sphalerite, and galena; 

manganese oxides occur in the oxidized zones. 

The San Juan veins, in the La Libertad area, are 4-8 feet wide. 

The ores are similar in mineralogy to the ores of the Santo Domingo 

area, but they c0ntain a higher percentage of silver. Supplies are 

generally transpcrted by rail from the Pacific coast to Granada, then 

by boat to Puert<' Diaz, and then by oxcart 50 miles eastward to the 

mines. An overls nd route passable only during the dry season extends 

around the lake. MATAGALPA AREA 

The mines in the Matagalpa district, about 80 miles north-northeast 

of Managua, are all controlled by the I. W. Bonbright Co., of New 

York. Supplies are brought to Managua on the Nicaraguan Railway 

and are then hauled by truck to the mines. The La Reina mine, 10 

miles east of Matagalpa, has several quartz veins 2-6 feet in width 

containing small ore shoots. About 9,000 ounces of gold and 20,000 

ounces of silver are produced annually from about 36,000 tons of ore. 

LA INDIA MINE 

The La India mine, operated by Compafiia Minera La India 

(Spencer, D. N., oral communication), about 50 miles north of 

Managua in the Departamento de Loon, comprises 2 principal veins: 

the La India and the Guapinol, about 4,000 feet apart, which trend 

northeastward and dip 50°-70° NW. The La India vein is 6-15 feet 

wide and is composed of fine-grained quartz which encloses considerable clayey material. Sulfides are absent, and the gold occurs as fine 

particles in the quartz. The vein is mined by means of adit levels 

to a depth of 180 feet and for 2,600 feet along the strike. About 9,000 

tons of ore is treated monthly, and the annual production is about 

30,000 ounces of gold and 40,000 ounces of silver. 
190 MINERAL DEPOSITS OF CENTRAL AMERICA 

EL LIM6N MINE 

:The El Limon mine, operated by the Empresa Minera de Nicaragua, 

is 25 miles northeast of Leon, in the low land between Lago de Managua 

and the Golfo de Fonseca. The vein, discovered in 1940, is 15-25 feet 

wide and is traceable for nearly a mile along the strike; the wallrock 

is andesite. A treatment plant with a monthly capacity of 9,000 tons 

was :put into operation in 1941. The production in 1945 was about 

30,000 ounces of gold and 10,000 ounces of silver. The El Limon 

operation also includes the San Luis and Santa Francisca veins, which 

were worked early in this century and whose ore was treated in a 

70-ton-per~day plant; this plant was closed in 1913. All the ·mines 

in the La India and El Limon districts are controlled by the N oranda 

Mines, Ltd., of Toronto, Canada. Freight is trucked from the Nicaraguan Railway to the mines. 

VERDE MINE 

The Verde mine, about 12 miles southeast of Matagalpa, was operated from 1920 to 1923 by J. A. Willey and others (Mines Handbook, 

1925, p. 2264) . Production totaling $15,000 net is reported to have 

been obtained with a 10-ton amalgamation plant. Two veins, each 

about 3112 feet wide, have been mined to a depth of 200 feet. One vein 

contains gold only, while the other also contains lead and copper 

minerals. 

SAN ALBINO MINE 

The San Albinp mine is 23 miles east of Ocotal, in the Departamento 

de· Nu~va·Segovia. The mine has been known since· colonial days, but 

it was not until 1922 that Charles Butters and some associates put 

~he. property into production. The surface plant was largely destroyed by revolutionists in 1928, and the property has not been reopened since. 

The ore body is a thick, lenticular quartz-pyrite vein several hundred feet long. It dips about 40°, parallel to the dip of the enclosing 

phyllites. Chalcopyrite is locally abundant in the lower levels. Other 

quartz veins are nearby. 

OTHER AREAS 

·Placer-gold production in Nicaragua has been small but persistent; 

part .of the gold is worked into filigree jewelry in the Caribbean coast 

towns. The principal placer areas are in the headwaters of the Rio 

Pis Pis, the Rio Bambana, and the Rio Prinzapolka, but deposits are 

also known to have been worked in the streams of the Chontales district. .In 1918 the Central American Exploration Co. (Mines Hand~ 

book, 1922, p. 1~80) was formed to prospect in the gravels of the upper 

part of the Rio Coco {also called Segovia and W anks) between the 

villages of Bocay, at the junction of the Rio Coco and the Rio Bocay, 
GOLD AND SILVER DEPOSIT8-NICARAGUA 191 

and Huililli, about 40 miles upstream hom the j~ction. The gravels 

were drilled during the 2-year exploration program, but the hydraulic program was not carried out. 

EL SALVADOR 

SAN SEBASTIAN MINE 

The San Sebastian mine is 3 miles west of Santa Rosa, a town on 

the Inter-American Highway, in the Departamento de La Union 

(Wuensch, 1917). The mine is at an altitude of about 700 feet and can 

be reached by an all-weather road from Santa Rosa. Although the 

mine was probably known to the Spaniards and may have produced 

gold during colonial days, the first recorded production was by an 

American company in about 1890. Subsequently the mine passed to 

the Butters Salvador Mines, Ltd., and was in production from 1900 

to 1920, when it was closed because of a decrease in the grade of the 

ore. The mill capacity was originally 1,200 tons a month and was 

later increased to 3,000 tons. In 1935 the mine was reopened, and 

production on a small scale has continued ever since. The mill capacity in 1945 was 40 tons a day. The recorded production of the mine 

up td 1945 was about $23 million worth of gold. 

The adits, drifts, and winzes are about 20 miles long and extend 

along the strike for about 1,800 feet and down the dip for 800 feet. 

The rocks in the area are chiefly basaltic and andesitic lavas and 

pyroclastic rocks of Tertiary age. 

The ore deposits are a series of branching quartz veins in a zone 

50-200 feet wide which strikes eastward. Most of the veins dip northward at angles ranging from 40° to 70° ; minor connecting veins 

dip steeply southward. The veins contain variable quantities of sulfides; the most abundant is pyrite, but there are minor quantities of 

chalcopyrite, chalcocite, bornite, tetrahedrite, molybdenite, and pyrrhotite. Small quantities of calcite, barite, and gypsum appear locally. Manganese oxides are present near the surface in some veins. 

The ore shoots in the veins contained from a few tons to several 

thousand tons of ore. Most of the high-grade shoots were small and 

erratically distributed throughout the veins. Some shoots contained 

ore with 3-50 ounces of gold to the ton, but the average was only 

about 11h ounces to the ton. Since the mine was reopened in 1935, the 

mill heads have been lower in grade, and some of the ore treated has 

come from old fills in the stopes which could be profitably treated 

when the price for gold went up to $35 an ounce. 

DMSADERO MINE 

The Divisadero mine (Mines Handbook, 1925, p. 2259) is in the Departamento de Morazan, at the village of Divisadero on the Inter388364--57----14 
192 MINERi\L DEPOSITS OF CENTRAL AMERICA 

:American Highway; abou.t 181 miles west of' Santa R0Sa ancl.i 16 miles 

east of San Miguel~ a: gtation: 6n1 the' International: Raillways of· Cent.ral 

America. The property was ineorp0rrnted in 1905: as the Butters 

Divisadero Co., and between 1905 and 1918 it yielded 93,971 ounces 

of gold and 5,657 ounces of silver which together had a gross value 

of $5,194,967. Most of the ore came from the Divisadero, Matilde, 

San Francisco, Carolina.,. and Pr.otectora veins, but a: small tonnage 

caine from the, Gig.a.nte mme, 6 miles east of" Divisadero. The value 

ef the ore mined. was repouted to have ranged fnom $5 to $8 per ton. 

ln 1919~ the property was. acquired by the El Salvador Silv-er Mines, 

Inc.,. and in 1923 it was.seld to. the Central.A.Inerican Mines, Inc. Except for an attempt to reopen the mine between, 1933 and 1935, tlmve 

has been no activity; since 1923~ and the mill, a cyanide plant of 350 

tons daily capacity (Swanquist, 1941, p~ 155), has. been dismantled. 

The workings extend to a depth o£ 700 feet down the dip of the 

Divisadero. vein, wh~h averages 65°, and for a length of more than 

2,000 feet. 

HORMlGUERO MINE 

The Hormiguet•o mine (Mines Handbook, 1918, p. 1797) is 6. miles 

south of the Divisadero mine, in the·Departamento de San Miguel. It 

comprises the Gallardu, Hormiguer0, and Guadalupe veins. The· property was controlled by the Comaearan Gold Mining Co. from 1909 

to 1920; and from about 1914 to 1918 it produced 208,096 tons of ore 

yielding $1,478,824 worth of gold and silver. The· ore was treated 

in a· cyanide plant of 180 tons daily capacity. 

The workings along the 3 veins are more than 37,000 feet in length. 

Mining extended 1,200:_2,200 feet along the strike and to a depth 

of more than 460 feet. The ore is in quartz veins. The Hvrm±guero 

vein contains silver-bearing sulfides; the Gallardo and Guadalupe ores 

are gold bearing~ 'Fhe veins also contain pyrite, sphalerite, galena, 

and chalcopyrite; the chalcopyrite is locally altered to malachite and 

azurite, and the northern part of the· Guadalupe vein contains considerable supergene manganese oxide. 

MONTE MAYOR MINE 

The Monte Mayor mine (Mines Handbook, 1925, p. 2264) is 14 miles 

northeast of the Divisadero mine. The mine is owned by Benjamin 

Gonzalez, who was operating a plant with a capacity of 60 tons a 

day in 1945. The property comprises the Monte Mayor, Santa Gertrudis, Carao, Tempisque, Banadeto, and Las Tunas veins. The ore 

shoots developed were for the most part small, and the production 

over a 3-year period was worth $233,818. The ore was treated in a 

10-stamp mill with a daily capacity of 60 tons. 
~GOLD AND SILVER DEPOSIT&-:-;EL ,S~VADOR 193 

POTOSi JUNE 

··The Pot<>Si mine is a.OOut 25 mi~s by road northwest of S11n Miguel. 

··The property Wii.SJ first opened &Rd. explored by tlae Butters Potosi Co. 

in the early 1900's. In 1919 the mine was acquired by the El Salvador 

:Silver Mines Co., s.Dd iR 1923 it po;ased to the {jenkal AmeriGan Mines 

:co. · In 1938· the ~rope:tty. was taken over by the..CG.tnp.a.iia .M.inera de 

•Oriente, and a 60-ton mill has been in operation since then. The ore 

jg said to be in -quartz veins in rhyolite and to be of high grade. 

MONTE CRISTO MINE 

The Monte Cristo mine is 15 miles east of San Miguel, oil the InterAmerican Highway, in the Departamento de Morazan~ The prop~rty 

'Was put 'into production about 1933 by Rene Keilhauer and E. P. 

Thompson. The workings total 39,000 feet. A 100-ton cyanide mill 

•powered by.diesel-electric motors is used to treat the ore. 

The ore is in ·several parallel quartz veins that trend northwestward 

:and dip 50°-75° NE. in altered volcanic rock. Individual ore shoots 

.are commonly small, but some contain as much as 100,000 tons with 

an average value of $10-$20 a ton, chiefly silver. ·The ore minerals are 

·sphalerite, argentiferous galena, pyrite, and gold. 

EL DORADO MINE 

The El Dorado mine is about 8 miles west of Sesuntepeque, in the 

-Departamento de Cabanas, on the road from San Rafael to Sesuntepeque. The property was acquired by the New York and Honduras 

-Rosario Mining Co. in 1943, and since that time the company has been 

·.exploring a system of closely spaced parallel quartz veins, which 

strike northward in volcanic rocks. The principal minera.l of value 

is gold, whi~h aeeompanies sparse pyrite in the veins. 

GUATEMALA 

Gold placers are known in Guatemala along the Rfo Motagua, the 

'Rio Bobos, and :also along smaller streams. Production at the ·present 

time is small, .but between 1924 and 1933 a dredge at Las Quebradas 

is said to have produced as much as $250,000 worth annually. 

LA CANOA PLACER DEPOSITS 

The La Canoa placers are about 22 miles upstream from Progreso 

·On the Rio Motagua. The river at this point makes a bend several 

miles in radius ·and is intrenched in a narrow valley cut in serpentine 

and mica schist. The placer deposits are in the present channel and 

in gravel benches along the margin of the channel. Operations are 

; generally carried on only during the dry season, between March and 

June. Attempts to employ mechanized equipment have been unsuc-

, cessful because ·:Of the short working season and heavy floods. 
·194 MINERAL ·DEPOSITS OF CENTRAL AMERICA 

LAS QUEBRADAS PLAC2R DEPOSITS 

The placer deposits at Las Quebradas are on the Rio Bobos, a 

tributary of the Motagua, 35 miles southwest of Puerto Barrios. The 

Las Quebradas mines operated in 1917 and 1918. An area of about 

300 aeres, known as the Potts and Knight concession, was purehased in 

1923 ·:by the Guatemala Gold Dredging Co. This company (Ludlum, 

1926) installed an 8-cubic-foot electrically operated dredge and began 

operations in December 1924. In the first 13 months of operation 

1,312,000 yards of gravel was treated, with an average recovery of 

about $0.2124 a cubic yard, yielding a total value of $278,610 in.gold 

bullion. Although much difficulty was experienced with heavy clay 

and large bo1;tlders in the gravel, operations continued until1933, when 

·the profitable gravels were exhausted. 

The rocks in the headwater area of the Rio Bobos are phyllite and 

schist intruded by granite and diorite (Sapper, 1937). Gold-bearing 

quartz veins are known to occur throughout this area, but none have 

been worked. These veins are probably the source of the placer gold 

that was concentrated where the Rio Bobos emerges from the 

mountains. 

PANAMA 

Except for a small production from placers, no gold was being mined 

in Panama in 1945. Small-scale operations were formerly carried 

on in the Provincia de Veraguas and the Proyincia de Darien. 

VERACUAS MINES 

The Provincia de Veraguas contains the most productive gold properties in Panama. The Panama Corp., Ltd., acquired the properties 

in 1925 but later leased them to the V eraguas Mines, Ltd. Between 

1934 and 1936 a total of 26,000 ounces of gold was produced from the 

Margaja and Cucuyo mines. The Remance and Mina Blanca properties also have been explored, but production figures are not available. 

The veins in the Provincia de V eraguas are in andesite. They contain gold associated with small quantities of pyrite, chalcopyrite, 

sphalerite, and galena. 

PLACER DEPOSITS 

Gold placers have been worked in the Provincia de Darien for many 

years. Before the arrival o:f the Spaniards in the 16th century, the 

Indians obtained gold from the stream gravels and fashioned it into 

orn~ments. The Spaniards knew of these deposits and probably 

worked them, but in more recent times only the Indians have produced placer gold. From 1931 to 1941_the gold exported has averaged 

about 5,200 ounces a year according to the Section of Mines of the 

Ministry of Agriculture and Commerce, Republic of Panama. The 

greatest production was in 1934, when 13,895 ounces was exported. 
REFERENCES CITED 195 

Gold placers: are: also.· worked in the Provincia de V ~;r~gu~, .i11, th~ 

streams below some of the gold mines. 

TUNGSTEN DEPOSITS 

Scheelite crystals were identified in a specimen of cop~r. ore from 

the Meta pan area. The locality was :visited in.N ovember 1943 and was 

found to be just across the frontier in Guatemala, oii the ranch of 

Felipe Heredia. 

. The rocks in the area are interbedded shale, sandstone, conglomerate, and limestone belonging to the Metapan formation of Cretaceous age. These rocks have been intruded by granite, . granite 

porphyry, and granodiorite stocks. One of the granodiorite stocks 

that crops out on the Finca Heredia has intruded the shale and limy 

shale and alte;red them to hornfels, which is the host rock oj the copper-tungsten deposits. Shear zones and fractures in the hornfels trend 

N. 50°W. 

The ore minerals are chalcopyrite, pyrite, and scheelite, which oc .. 

cur ill small pockets scattered throughout the hornfels,. and. ·also as 

di~eminated grains .. The scheelite grains range in diameter from the 

size of pinpoints to half an inch. Epidote, c~i~,. and: quartz commonly occur with the ore-forming minerals. The sulfides are distributed erratically throughout a shear zone that is 8-12 feet wide, trends 

N. 50° W., and dips 60° NE. The copper content of the shear Z<me 

is low and is estimated to be less than 1 percent over a width of 8 feet. 

The outcrops were examined for scheelite at night with the. aid of an 

ultraviolet lamp. Two rock faces were found to contain scheelite, but· 

only a few crystals were seen. Elsewhere the rock is barren, but since 

much of the area is covered with soil and vegetation, other· concealed 

occurrences may exist nearby. Many specimens of contact-metamorphosed rock from the ~etapan and Alotepeque districts were subsequently tested for scheelite, but none was fou11d. 

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Bengston, N. A., 1926, Notes on the physiography of Honduras: Geog. Rev., v. 

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Bennet, Evan, 1939, Gold mining in Costa Rica: Eng. and Min. Jour., v. 140, no. 

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Brown, T. T., Collins, E. B., and Hess, H. H., 1933, The Navy-Princeton gravity 

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Bucher, W. H., 1947, Problems of earth deformation lllustrated by the Caribbean 

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Carpenter, R. H., 1954, Geology and ore deposits of the Rosario mining. district 

and the San Juancito Mountains, Honduras, Central America : Geol. Soc. 

Am. Bull., v. 65, p,.-23-88. 
196 MINERAL DEPOSITS OF CENTRAL AMERICA 

Dollfus, Auguste, and Montserrat, E. de, 1868, Voyage g00logique dans les repufi.oiiques de Guatemala et de Salvador: Paris, Mission Scientifique au Mexique~ 

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Dunbar, C. 0., 1939, Permian fusulines from Central America: Jour. Paleontol--

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Engineering and Mining Journal, 1920, The Rosario mines in Honduras : Eng.-

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Fleury, Louis, 1917, Minerologfa, metalurgfa, y geologia ec6nomica de El Salva--

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Flores, Giovanni, 1952, Geology of northern British Honduras: Am. Assoc. Pe-~ 

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Garbrecht, Louis, 1920, New mining fields in eastern Nicaragua: Eng. and Min;. 

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Haley, C. 8.,1941, Honduras, pioneer frontier: Eng. and Min. Jour., v. 142, no. 6,. 

p. 35-38. 

Hawxhu.:rst, Robert, Jr., 1921, The Pis Pis gold district, Nicaragua: Min. and Sci.-

Press,v.122,p.853-860. 

Hayes, C. W., 1899, Physiography and geology of region adjacent to Nicaragua1 

Canal route: Geol. Soc. Am. Bull., v. 10, p. 285-848. 

Hershe-y, 0. H., 1912, Geological reconnaissance in northwestern Nicaragua: 

Geol. Soc. Am. Bull., v. 23, p. 493-516. 

Hess, H. H., 1933, Interpretation of geological and geophysical observations;· 

U. S. Hydrographic Office Navy-Princeton gravity exl)edition to tlie West 

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&uk, L. G., 1M2, Marketing strategic mica: U. S. Bqr. of Mines Inf. Circ. 7219,. 

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Huttle, .J. B., 1942, A visit to the Aguacate district in Costa Rica : Eng. and Min .. 

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Imlay, R. W., 1!W®, .Tll.rassic formations of Gulf Region : Am. Assoc. Petroleum1 

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Jones, S.M., 1950, Geology of Gatun Lake and vicinity, Panama: Geol. Soc. Am .. 

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Kesler, T. L., and Olson, J. C., 1942, Muscovite in the- Spruce Pine district, North• 

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Eng. and Min Jour., v. 143, no. 8, p. 114-115. 

Knowlton, F. H., 1918, Relations between the Mesozoic floras of North and South 

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Leggett, T. H., 1889, Notes on the Rosario mine at San Juancito, Honduras:-

Am. Inst. Min. Engineers Trans. 17, p. 432-449. 

Lemus, Manuel, 1917, Datos para la historia de la mineria en la Republica de· 

Guatemala : 2d Pan Am. Sci. Cong., v. 8, p. 960-962. 

Ludlum, A. C., 1926, A successful gold-dredging enterprise in Guatemala: Eng .. 

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Malozemoff, P., 1942, Costa Rica, from a symposiu~ on mining in Latin America: 

Eng. and Min. Jour., v. 143, no. 8, p. 113-114-. · ., 

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Mierisch, B., 1895, Eine Reise quer durch Nica:r-agWil. V()m Mamagua---,See ibis- nacb 

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Miillerried, F. K. G., 1936, Estratigra1la pretercia.:ria ;preliminar del Esta.do .d~ 

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198 MINERAL DEPOSITS OF··· OENTRAL AMERICA 

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METRiC EQUiVAL~NiS 

TEMPERATURE LINEAR MEASURE WEIGHTS ....__ 

co Fo Centi- Inches Meters Feet Kilo- Miles Kilo· Pounds Metric Long Metric Short 

meters meters grams (avoir.) tons tons tons tons 

70.1- 100 --r 40 100 IOOl 1001- 100 -;-·110 

- 150 60 601140 90-l 900 3000 90 90 I 200 90- 90 90-~·100 

- -- 130 80--- 800 80 50 80 so· 80 80 90 

50 120 -l 30 2500 ~ -}!10 70 700 70 70 150 70 70 70 1-3 

40 100 

I !;:1:1 

601 600 -t·-_2000 

40 70 s 60 60 60 60 60 

30 -r-90 6Q- ~ 

80 

:~20 500 :t .-. 50 50 50 50 50 § 

20-1 70 ·1500 30 100 

60 400 40 40 40 40 40 ~ 40 ~ 

10-+- 50 ~ 

30i 300 1000 30 30 30 30 30 40 30 l1l 

10 

O-L3o 20 200 20 20 50 20 20 :.:::u-1- 20 

20 500 10 

10 -j- 10 10 100 10 10 10 10 10 ---i- 10 

20 .....l,_ 0 0 0 0 .....:l__o 0-2.. 0 0__1_ 0 0 ___l__ 0 0 

1 em. = 0.3937 inch 1 meter = 3.2808 ft. 1 km. = 0.6214 mile 1 kg. = 2.2046 lbs. 1 metric ton = 0.9842 long ton 

1 inch = 2.5400 em. 1 ft. -= 0.3048 meter 1 mile = 1.6093 km. 1 lb. = 0.4536 kg. 1 metric ton == 1.1023 short tons 

1 sq. meter = 1.20 sq. yd. 1 metric ton= 2205 lbs. 

1 hectare = 2.47 acres 1 long ton = 1.0161 metric tons 

1 cu. meter = 1.31 cu. yd. 1 short ton = 0.9072 metric ton ....... 

co 

cp ,.,.,. 
\. 
INDEX 

A 

Page 

Acknowledgments ___ -------------------______ 4 

B 

Bas Obispo formation._---------------------- 29-30 

Bohlo formation.----------------------------- 29-30 

c 

Caimito formation____________________________ 31 

Cantarranas formation_______________________ 20 

Chochal formation _____________ . ________ 16-19,85,100 

CoMn formation _____________________ 23, 58,100, 104 

Colonia formation____________________________ 20 

Cornuspira sp. __ ----------------------------- 18 Costa Rica, copper deposits __________________ 61-62 

gold and silver deposits----'------------- 184-186 

iron deposits______________________________ 72 

manganese deposits _____________________ 105-106 

mining areas, Aguacate __ _.________________ 184 

ConcepciOn___________________________ 61 

Esparta. _ ---------------------------- 185 Guayabo _____________________________ 61,62 

Las Juntas. _____ -----------~--------- 184 

Miramar_-------------------------~__ 185 Rio MadrigaL_______________________ 186 

Rio Nuevo.-----------~-------------- 186 Rio Tigre_____________________________ 186 

San RafaeL-------------------------- 61,62 

.San Ramon •.••. ---------------------72, 186 Crassatellites ______________________ ----- ___ ____ 20 

Crucero formation •. ------~------------------- 20 

Cucaracha formation.--------------------____ 31 

Oulebra formation _______ ---------------______ 31 

E 

El Plan formation _________________________ 19-20, 34 

El Salvador, gold and silver deposits .. _____ 191-193 

lead-zinc deposits _________________________ 73-83 

mining areas, Canas Dulces. __ ----------- 78 

Chaguite ________ --------------------- 77 

Divisadero. _ ----------------------- 191,192 

El Carmen___________________________ 77 

La Cerbita___________________________ 76 

Metapan __________________________ 73-74,77 

Quebrada del Tigre___________________ 78 

Rio Casaquaste_______________________ 74 

Rio San MigueL_____________________ 78 

San Isidro____________________________ 77 

San Juan _____________________________ 74,76 

San MigueL_________________________ 193 

Santa Rosa___________________________ 191 

Sesuntepeque _______ ------------------ 193 

quicksilver deposits. ______ --------------- 174 

Endothyra sp. _ ---------------------------~--- 18 

Eoverbeekina american.a. _ --------------------- 17, 18 Es.qulas formation____________________________ 22 

Ez_ogy~a arietina. __ ------------------- ____ ____ 22 

G PageGatlln formation~ ____ ------------------------ 31 

Gatuncillo formation_------------------------ 29 

Geologic structure ..•. ___ ~------ ___ --~----· __ • 33-36 

Gryphaea corrugata____________________________ 20· 

Guatemala, antimony deposits--------------- 47 . chromite deposits _________________________ 48-55 

copper deposits--------------------------- 56-58 

gold and silver deposits.-------------~- 193-194 

iron deposits •• ------------------"·-------- 72 lead-zinc deposits ________________________ 73-104' 

manganese deposits--~-~-------------- __ 141-142 

mica deposits __ · _____ ----------------·---- 142-160 

mining areas, Aguas Blancas_____________ 102 

Alotepeque _______________________ 73, 78,195 

Cabafias ____________________ -:c--------- 48,52 

CahabOn~ ---------------------------- 57 

Camot(m ____ ~ _ ~ ~ ~ ----- __ -_ ---- _- ~- ~-- 72 

Caqun ____ --------------------------- . 153 Caquipoo______ ___ ___ _ _ _ _ __ _ __ _ _ ___ ___ 104 

Carboneras ___________ ---------------- 47 . Chlantla _____________________________ 84,87 

Chinautla_ --------- _ ---------------- _ 58. Chinique _______________________ --- __ _ 169· 

·Chiquimula.c ___ ;_·--------------- -57,72,141 

· Ohi:rrUm. _______ c ____ ---------------- 166. Oob!\n_· _________ .c •• _________________ 99-100 

·Cordillera del Sauce__________________ 72 

Cubulco ___________ c ____________ 167,168, 169> 

El Chanco____________________________ 72 

· El ChoL: .. :.: .•. c ••• __________ 157,164,165-

. ElM-oraL:.:_________________________ 72· 

El Pante6n de San Jos~ de Aii\da_____ 72· 

El Pericon____________________________ 156 

El Tituqne___________________________ 72 

Granadas.----------------~--------- 157, 158. 

Jalapa •.• ----------------------------- 48,51 Joyabaj __________ : __________________ 148, 152· 

La Canada___________________________ 79· 

Las Jobas. __ ------------------------- 165 Las Lavaderas ___________________ :____ 92· 

·Las Quebradas.-------------------- 193,194 

Los Cimientos________________________ 169· 

Los Pinos mining camp_------------- 54 

Mataqnescuintla. _________ :·------ _ --- 56 

Morazan ___ -------------------------- 48, 55. 

· Olapa ___ ----------------------------- 47 Pachalfim __________________ 148,152,154,155 

Palencia ... --------------~------------ 47 PurulM ___________________ ~----- ----- 103 

RabinaL ----------------------------- 166 

Rabinala. ---------------------------- 169 

Rio Bobos.------------------------- 193,194 

Rio Chimil'apa __ --------------------- 53 

Rio 'Concepcion~_-------------------- 81 Rio Coya ___________________ .__________ 96· 

Rio de las Minas_____________________ 80 

Rio de las Vacas______________________ 58 

Rio Motagua .. :: ... ~------------:·.-:-- 193. 

20l 
202 lNDEX 

Guatemala-Continued 

mining areas-Continued Page 

Rio Oxek----------------------------- 57 Rio Pasaguay________________________ 156 

Rto Santa Catarina ___________________ 94,97 

Rio Tzitzi}___________________________ 155 

Rosario_______________________________ 141 

Salama ____ --------------------------- 55 

Saltfi.n ________ ------------------------ 160 

San CristobaL--------------------- 101,102 San Diego____________________________ 55 

San Mateo Ixtatan. ------------------ 56 

San MigueL.------------------------ 96,97 

San Miguel Aca.tA.n___________________ 94 

San Rafael Saltfi.n____________________ 160 

Santa. BA.rbara.________________________ 58 

Santo Domingo_______________________ 102 

Sierra de los Cuchumatanes. --------- 85 

Socorro _________ ---------------------- 79 

Suquinay --------------------------- __ 103 

Sutdn------------------------------ 167, 168 

Tactic ____ ---------------------------- 102 

Trapiche Grande--------------------- 58 Tucurft _____________________________ 103,104 

Volcancillos __ ------------------------ 156 

<quartz deposits------------------------- 161-169 · 

'qui<*silver &Posits---------------------- 174 

'tungsten deposits ••• ---------------------- 195 

Gnatemala-El Salvador coastal plain_________ 6 

H 

Honduras, antimony deposits ________________ 39-47 

·copper deposits--------------------------- 58-61 ;gold and silver deposits _________________ 175-184 

iron deposits------------------------------ 64-71 

:manganese deposits--------------------- 135-140 :nlinlng areas, Aga.lteca.____________________ 64 

Aramecina. __ ------------------------ 71 

Batea. ------------------------------- 180 

Cedros. ----------------------------- 44, 179 

Cerro ColoradO.----~----------------- 71 

Choluteca. __ -------------------------- 181 

Comayagua __ ----------------------- 60, 178 

CopA.n ______ -------------------------- 45 

Corral _____ --------------------------- 182 

DanlL------------------------------ 176,180 

.El Paralso •• -------------------------- 179 

El Progreso--------------------------- 46 El Retiro_____________________________ 183 

Honduras -Continued 

mining areas-Continued Page 

Pedernales. __ ------------------------ 44 

Pespire----------------------------- 136,140 

Petoa·-------------------------------- 59,60 

Pino Alto. __ ------------------------- 179 

Puertecito ________ --------------·----- 45 

Rio Chiquita_________________________ 60 

Rio Gua.ya.pe_________________________ 183 

Rio Guaymas________________________ 46 

Rio Jalan.----·----~-------------"-~---- 183 

Rio Jicatuyo_ ------------------------ 172 

Rio Ma.cutla.. __ ---------------------- 60 

Rio Mangullle-----~------------------ 46 

Rfo Patum~--------------------------- 184 Rio Pa.ulaya__________________________ 184 

Rio Segovia__________________________ 184 

Rio Sico •. ---------------------------- 184 San Agustin __________________________ . 39 

San Antonio de Oriente---------~---- 180 

San Martin ••••• --------------~----- 181,184 

San Rafael Paraiso ••• ---------------- 61 Santa Barabara._______________________ 172 

Santa Lucia__________________________ 44 

Santa Rosa de Cop{m_________________ 178 

Sierra de Comayagua. ___ ._"'------------ 64-66 

Sierra Prieta-------------------------- 45 

Suyatal ___________ ------------------ __ 44 

Tatumbla. ________ ------------------- 182 Tegucigalpa ____________________ 138,175,180 

Tendal--------------------- _· _____ .;___ 137 

TeupacentL------------------------- 183 

Villa. Nueva...________________________ 138 

Yoro. ---------------------------- 44, 61, 179 

quicksilver deposits ••• ----------------- 169-174 

I 

Ixcoy formation._---------------- 22-23,95,96,97,98 

L 

LaBocaforma.tion ___________________________ . 31 

Lago de AmatitlA.n. _ ------------------------- 36 

Lago de AtitlA.n.----------------------------- 38 

Lago de llopango •• --------------------------- 36 

Las Cascades formation.-----------~--------- 29-30 

M 

Meta.J)An formation _________________ 19, 20, 21-22,63, 

65, 73, 76, 82, 169, 170, 173, 180, 182,'187, 195 . 

El Rusio_____________________________ 183 Metric equivalents(table). __ ----------------- 199 

Goascoran _____ ----------------------- 181 

Guam pd._--------------------------- 184 

.Jala.ca._ ------------------------------ 46,170 

JaraL __ ------------------------------ 182 

Juticapla. ---------------------------- 178 La Union_____________________________ 46 

La.go de.Yojoa..----------------------- 44 

LanguL.-------------------------- 179,184 

Los Izotes---------------------------- 169 

Macuellzo. ------------------------- __ 184 

Mangulile ____ ---------------------- __ 179 

Minas de Oro.---------------------- 61,184 

Montaitita. __ ------------------------ 180 

MoroceH. __ -------------------------- 139 

Nispero. _ ---------------------------- 60 OcotaL ________ ----------------_ -----_ 183 

Ojojona •••• -------------------------- 59,139 

Mines and prospects, AdA.n prospect__________ 53 

Adllio mine •• _--------------------------- 78 

Aga.lteca. deposits------------------------- 64-71 

Agua. Frla mine-------------------- 174,176-178 

Agustin deposit. __ ----------------------- 55 

Almengor mine ••• ------------------------ 94 

Amatlllo deposit__________________________ 139 

America. prospect------------------------- 117 

Anderson mine.-------------------------- 178 Antlllean cordlllera._______________________ 5-6 

Aramecina. deposits----------------------- 71 

Atutilca. mine._-------------------------- 78,82 

A1Istralla. mine._------------------------- 55 

Bella Vista. mine------------------------- 186 

Benjamin mine·--------------------------- 44 

Bergua no. 1 mine------------------------ 148 

Blaque prospect-----------------------· 115-116 
IND;EX 203 

Mines and prospects-,Continued l'~" l MineS and prospects-Continued Page 

Bola de Oro mine.·---~---~~--------------- 97 Guadalupe mine·----------------------~-- 7& 

Bonanzagroup. SeeNeptune-Edengroup. Guayabillas mine------------------------- 180 

Bonanza mine •. -------------------------- 185 Guayabo deposits._-------------"--------- 62 

Boston m!ne.----------------------------- 185 Harriet prospect.----------------------- 129-130 

Brenes prospect_------------------------- 141 Hidden Treasure mine-------------------- 188 

Buena Vista mine-------------------·---- 94 Horm.iguero mine------------------·------ 192 

Buenos Aires mine------------------·. 49, 00,54 Hyatt no. 1 mine.---------------------- 121-124 

Oandelarla.·prospect. ----------------· ---- 99 Hyatt no. 2 mine----------------------- .124-128 

Capiro mine------------------------------ 180 Izotalmine •. --------------------- ___ ----- 167 

OapitOOi prospect.--------------------·-- 173-174 Jaball deposit [chromite] .•. -----------~-- 53 

Caquipoo mine--------------------------- 104 JabaU mine [gold and silver]______________ 189 

Oerro Bonito prospect·---------------·---- 138 June prospect.---------------------------- 119 

Oerro Vivo prospect------------------·---- 58 La Adllia mine.-------------------------- 157 

Ohacon !)line .• ~-----------------------·---- 146 La Alhambra mine_______________________ 180 

Ohaquite deposts------------------------- 77-78 La Ballena mine~------------------------- 80-81 

Ghautulul prospect.______________________ 168 La Cabrera mine---"---------------------- 159 

Ohinique mine--------------------------- 162 La Cadena prospect..-------------------- 47-48 

Chipacapox mine.------------------ 162,166-167 La Camelia prospect---------------------- 103 

Ohirruman prospect. _________________ .____ 168 La Ca.fiada mine. __ -------------------- 17D-172 

Chochal prospect------·------------------ 9Q-91 La Canoa placers------------------------- 193 

Conchagua mine .• ----------------------- 179 La Ceiba mine.--------~----------------- 50,53 

Gonstancia grOUP----------------------- 187,188 La Constancia mine.------------------- 157-158 

Corona mine----------------------- 49, 50,51-52 La Corona deposits _________________ 49, 50,53-54 

Corral mine .. ---------------------------- 188 La Cumbre deposits-------------------- 141-142 

Coyolito prospect--------------------··---- 173 La Esperanza mine [chromite] ____________ 49,50 

Cucuyo mine .... ----------------------·---- 194 La Esperanza mine [lead-zinc] _________ 87,92-94 

Culebra mine-------------------------·---- 188 La Esperanza mine [mica]-------------- 158--159 

Curiol mine.------------------.. ---------- 105 La Esperanza prospect--,---------------- 77 

Divisadero mine ..• ---·---------~-------- 191-192 La Gringa mine.------------------------- 49,51 

Dolores deposit.-------------------------- 169 La Independencia mine___________________ 49 

Don Enrique deposit----------------··---- 53 La India mine---------------------------- 189 

ll!:den mine.-------------------------··---- 188 La Joya mine----------------------------- 49,53 

Jl!:l Amatillo prospect----------------··---- 59 La Joyita mine--------------------------- 50 

Jl!:l Anono no. 1 mine .. ________ .: ____ 146, 147,152 La Luz mine--------------------------- 186-187 

Jl!:l Anono no. 2 mine._----------------- 152-153 La Matilda deposits _______ :_ ____________ 131-134 

:11:1 Audiencio deposit..---------------·---- 50,54 La Mesa prospect---------------------- 116-117 

:11:1 Brujo mine._--------------------··---- 77 La Paz mine----------------------------- 50,52 

:11:1 Candon prospect------------------·---- 168 La Paz no. 1 mine------------------------ 49 

:11:1 Carrizal prospect------------------·---- 47 La Reina mine.-------------------------- 189 

:11:1 Chico deposit--------------------.. ·--- 55 La Sara mine .. --------------------------- 92 

:ll:l Cho1 mine. See Santa Lucia mine. La Union mine-------------~------------- 46-47 

:ll:l Chorro mine. __ -------------------·---- 79,82 La Victorina mine------------------------ 179 

:ll:l Cipres no. 1 mine ________________ 146,153-154 La Virginia mine------------------------- 158 

:ll:I Cipres no. 2 prospect--------------·-- 146,154 Las Chacaras mine _______________________ 6Q-61 

:1!:1 Corpus deposits __________________ .. __ 181-182 Las Flores deposits_______________________ 45 

:1~1 Corral Viejo deposit ______________ .. ____ 50 Las Guayabas mine______________________ 146 

:ll:l Cuervo deposit--------------------·---- 55 Las Quebradas placers-------------------- 194 

:ll:l Dorado mine----------------------·---- 193 Las Tab las deposit.---------------------- 47 :ll:l Encante mine ____________________ .. ____ 185 Libertad and Margareta prospect.________ 160 

:ll:l Guapinol prospect_ _______________ .. ____ 50,53 Llano Brenes mine_______________________ 186 

:B:l Horno prospect_ __________________ .. ____ 47 Lorna Chamuscada deposit_______________ 60 

:ll:l Inocente mine ____________________ .. ____ 50 Los Amates deposit_ ___________________ 165-166 

:ll:l Jocote prospect .. -------------------- 146,155 Los Cimientos mine---------------------- 162 :ll:l Limon mine ______________________ .. ____ 190 Los Hornitos mine ________________________ 44-45 

:ll:I Mochito mine .. ------------------------- 182 Los Iwtes mine ________________________ 169-170 

:ll:l Per6z no. 1 mine __________________ .. __ 146,160 Los Limones mine ..... -------------------- 162 

:ll:I Pino prospect._------------------.. ·--- 160 Los Mangos mine------------------------ 60 

:ll:l Pino Seco deposit ________________ .. ____ 53 Los Sandillales prospect__________________ 57 

:ll:l Porvenir mine ____________________ .. ____ 181 Los Tablones prospect .. ------------------ 156 

:ll:l Quetzal mine .. ------------------------ 39-44 Los Volcancillos prospect ___________ 146,154-155 

:ll:I Rosario mine ... ----------------------- 175-176 Machita deposit-------------------------- 115 

;ll:l Tajado mine .. -"--------------------·---- 76-77 Macutla prospect------------------------- 60 

:ll:I 'l'r{msito mine.------------------------ 181 

l~lor Azul prospect .. _-------------------- 139 

Gigante mine ... --------------------------- 192 

Gracias li Dios deposit .. ------------------- 53 

Malachate prospect ______________________ _ 

Mangue de Indio prospect. ______________ _ 

Mangulile mines-------------------------

Margaja mine.---------------------------

138 

114 

178 

194 
204 INDEX 

1\rliries and prospects-Continued Page Mirtes and prospects-Cbntiilued" Page Marfa-Defense prospect_ ______________ 117-119 San Fernando mine ______________________ 81-82 

Mariana d!Jposit__________________________ 119 San Franclllco mfile~---------- "----------- 46 

Mataquescuintla mine ____________________ 56-57 San Gerardo mine------------------------ 186 

Mercedes mine___________________________ 180 San Gregorio mine------------~----------- 189 

Mii:ul Blanca mine________________________ 194 San Isidro Montaftita prospE!cfst__________ 77 

Mina Vieja deposit_______________________ 102 San Isidro-San~OertrudiSm:i.Jte'_________ 181 

Mine 1.---------------------------------- 110 San Joaquin mine----~-------------- 99,101-102 

Mine 2--------------------------------- 11o-111 San Jose mine---------------------------- 78,82 

Mine 3----------------------------------- 111 San Jose Grande mine____________________ 81 

Mine 4----------------------------------- 111 San Juan mine [gold and sfivet)' _________ 181,189 

Mineral de Ochre mine___________________ 91 San Juan mine [lead-zinc] _________________ 74-76 

Montaftita deposit ___ -------------------- 180 San Juan prospect [chromite1~------------ 50,54 

Monte Cristo mine_______________________ 193 San Juan prospect [quai'tZl--------------- 167 

Monte del Aguacate mine.--------------- 61 San Juancito prospect ________ ----~------- 50,54 

Monte Mayor mine---------------------- 192 San Martin deposits __________ ----------- 181 

Monte Verde deposit_____________________ 78 San Mateo prospect---------------------- 56 

-Montezuma mine________________________ 186 San Pantale6n mine---------------------- 78,79 

Morning Star mine_______________________ 188 San Pedro mine-------------------------- 50,53 

Mostroncosa deposit ____________________ 113-114 San Rafael deposits [copper]~------------- 62 

Neptune-Eden group ___________________ 187, 188 San Rafael mine [gold and sll'v'erl~-------- 185 

Novillo mine_____________________________ 180 San Rafael mine [lead-zinc]:. ______________ 78,82 

Nuestro Amo prospect_ _________________ 134-135 San Sabasti!m mine---------------------- 104 

·Nueva Wellington mine__________________ 159 San Sebastiii.n mine_______________________ 191 

Ojojona deposits ________________________ 139-140 San Victor deposit ________________________ 50,55 

Opoteca mine-------------------------- 178-179 San Vincente mine_______________________ 78 

·Oreamuno-Castro mine _________________ 184,185 Santa Cruz prospect______________________ 61 

Palibatz no. 1 mine _________________ 146,149-151 Santa Elena mine ______________________ 180,185 

Palibatz no. 2 mine _____________________ 146,151 Santa Fortuna mine---------------------- 180 

Pampujmay mine ----------------------- 102 Santa Ines mine-------------------------- 59 

Panama prospect ---------------------- 11'4-115 Santa Lucia mine [gold and silver]~------- 180 

"Poaj mine _____________ -___________________ 146 Santa Lucia mine [quartz] __________ 162; 164-165 

Paraxa prospect__________________________ 168 Santa Margarlte mine____________________ 181 

:Paz deposits ____________________________ 172-173 Santa Rita mine. See Rosita mine; 

Perez prospect____________________________ 141 Santa Rosa prospect ____________________ 146,155 

Peten lowland____________________________ 5 Santa Rosalia mine_______________________ 78 

Petoa deposits ____________________________ 59-60 Santa Sofia mine_________________________ 81 

Philadelphia mine________________________ 188 Santa Vincenta deposit___________________ 53 

Pioneer-Lone Star group ________________ 187,188 Santo Domingo mine [copper]____________ 60 

"Plomosa Grande mine____________________ 80 Santo Domingo mine [lead-zinc]__________ 102 

Pomaxan prospect________________________ 168 Sechfm prospect------------------------- 156 

Potosi mine______________________________ 193 Sepacay deposit_ _______________________ 102--103 

Pozo deposit_ ---------------------------- 140 Sequilha prospect_ _____________________ 103-104 

Providencia prospect_____________________ 82 Silak mine. See Rosita mine. 

Quebrada de Ruben prospect_____________ 137 Siria mine________________________________ 44 

Quiac6j prospect__________________________ 156 Suquinay prospect.______________________ 103 

Quitagana mine-------------------------- 182 Tajo de Montenegro mine________________ 80 

Remance mine--------------------------- 194 Talaxc6c prospect._______________________ 156 

Rey del Oro mine________________________ 178 Tatumbla mine__________________________ 182 

Rio Guayape placers ___________________ 182-184 Tendal mine ___________________________ 135,137 

Rio Jalan placers _______________________ 182-184 Tesoro mine______________________________ 188 

Rio Navagana deposits _________________ 109-110 Toloxcoco mine.- ---------------------- 162,166 

Rosario mine _____________________________ 96-97 Torl6n mine_---------------------------- 87-90 

Rosita mine ______________________________ 62-63 Trapiche Viejo mine______________________ 165 

Sabana Grande mines____________________ 181 Tres Hermanos mine_____________________ 185 

Sacrafamilia mine ______________________ 184,185 Trinadad mine___________________________ 185 

Salvador mine____________________________ 50 Tuno prospect____________________________ 53 

San. Albino mine._---------------------__ 190 Tziminas mine_-------------------------- 91 

San Andres mine_________________________ 178 Tzitzil prospect------------------------- 146,155 

San Antonio deposits _____________________ 50,55 Union mine ____________________________ 184,185 

San Antonio de Oriente deposit___________ 180 Valle de Angeles mine____________________ 180 

San Augustin mine_______________________ 50 Venado prospect__________________________ 173 

San Bartolo mine ________________________ _ 82 

San Carlos mine ___________________________ 78,82 

San Casimiro mine_______________________ 76 

San F~lix mine___________________________ 179 

San Fernandez mine______________________ 46 

Ventura prospect. See Panama prospect. 

Venus no. 2 mine.------------------------ 188 

Verde mine________________________________ 190 

Veta Grande mine __________ -------------- 180 

Villa Linda mine.----------------------~- 97-99 
INDEX 205 

Mines and prospects-Continutd Page 

Xea.baj mine______________________________ 153 

Xeul mine------------------------------- 162,167 

Yuscaran deposits----------------------·· 18o-181 Zuh6j depOsits _____________________________ 57-58 

N 

Nicaragua, antimony deposits __________________ 47-48 

copper--deposits _____ ------------- ___________ 62-63 

gold and silver deposits ___________________ 186-191 

iron deposits_________________________________ 72 

mining areas, Achula.pa______________________ 72 

Boaca.. _______________ ------------- _ __ _ 72 

Boca.y -----------------------··-------- _ 190 Cerro Santa Rita________________________ 62 

HuilillL __________ ------------------. __ 191 

La Libertad-------------------------- i89 

Leon ___________ ------ __ ----------- __ ._ 190 

Managua______________________________ 189 

Monte Carmelo______________________ 62 

OcotaJ.______________________________ __ 100 

Palaca.guina ____________________ ------ 48 

Pis Pis.---------------------·-------- 72,187 

Rio Bambana------------------------ 190 Rio Coco_____________________________ 190 

Rio Pis Pis.-------------------------- 190 

Rio Prinzapolka --------------------- 190 

Rio Songuas__________________________ 72 

Rosita ____________________________ ---- 62 

Santo Domingo_______________________ 189 

Siuna_____________ ___ _ __ __ ____ __ _ __ ___ 186 

0 

OBtrea. --------- _____________________________ _ 20 

Panama-Continued Page 

mining areas, BPhia de Mandinga. ______ 106,110 

Bahia de Montijo_------------------- 129 

Calzada Larga________________________ 128 

Cerro VieiO--------------------------- 117 Mesa Peak___________________________ 116 

Nombre de Dios ________ 106,111,113,115,119 

Nuestro AmO------------------------- 134 

Ponuga _____________ ------------------ 131 

Quebrada Luis _____________ ---------- 119 

Quebrada Macho_____________________ 115 

Quebrada Mangue de Indio__________ 114 

Quebrada Mariana------------------- 119 

Quebrada Ventura___________________ 114 

Rfo Boqueron ______________ 119-120,121,124 

Rio Navagana·--------------------- 109, 110 

Parafusulina amtraliB.------------------------ 17,18 

guatemalaensis ___ _______ -------- ______ ---- 18 

sapperi. ---- ___ • ________ ---- __ -- _____ ----- 18 

SP------------------------------------- 16, 17,18 Pholadomye ____ _______________ ------- _______ -- 20 

Plancitos formation___________________________ 20 

Pliohippus hondurensfB_______________________ 27 

8 

Santa Rosa formation. ___ 15-16,34,85,86, 95,100,143 

Schwagerina figueroaL. ----------------------- 15 gruperaensiB _______ • ______ --------- _ _ _ _ _ _ _ 16 

sp ____ ------------------------------------ 16, 18 

Sepur formation-------------------- 23, 34, 58, 95,100 

Simons, Frank 8., Panama [manganese deposits] ____________ -------------- 106-135 

T 

Todos Santos formation______________________ 19, 

p 

Pacific coastal plain __________________________ _ 2o-21, 22, 34, 56, 85-86, 95, 96 

6-7 Tegucigalpa formation. See El Plan formaPanama [manganese deposits], by Frank S. tion. 

Simons. ____ -------------- ____ ._ 106-135 v Panama, gold and silver deposits ___________ 194-195 

manganese deposits--------------------- 106-135 Valle de Angeles formation __________________ _ 24 

0