UNITED STATES DEPARTMENT OF THE INTERIOR 

Harold L. Ickes, Secretary

GEOLOGICAL SURVEY 

W. C. Mendenhall, Director

Bulletin 935-B

MANGANESE DEPOSITS OF CUBA

BY

CHARLES F. PARK, JR.

Geologic Investigations in the American Republics, 1941-42 

(Pages 75-97)

UNITED STATES

GOVERNMENT PRINTING OFFICE 

WASHINGTON : 1942

For sale by the Superintendent of Documents, Washington, D. C. Price 10 cents

CONTENTS

Page

Abstract................................................. 75

Introduction............................................. 76

General geology.......................................... 76

Orlente Province..................................... 77

Plnar del Rio Province............................... 79

Las Villas Province and Isla de Plnos................ 80

Economic geology......................................... 80

Mineralogy........................................... 80

Manganese minerals............................... 80

Other minerals................................... 81

Classification of the deposits....................... 83

Deposits in tuff................................. 84

Deposits in limestone............................ 85

Granzon.......................................... 86

Miscellaneous deposits........................... 87

Relation to bedding.................................. 88

Relation to faults................................... 90

Origin of the bedrock deposits....................... 90

Production........................................... 95

Economic factors..................................... 95

Method of mining................................. 96

Method of concentration.......................... 96

Future of the deposits............................... 97

ILLUSTRATIONS

Page

Plate 21. Index map of Cuba and location of Cuban manganese districts.............................. 78

22. A, Manganese oxide pocket in limestone, El

Tony prospect, Oriente, Cuba.............. 86

B, Manganese oxide fragments in limestone,

Charco Redondo mine, Oriente, Cuba....... 86

23. A, Granzon from La Cuca mine, Pinar del Rio,

Cuba..................................... 87

B, Veinlets of tuff in manganese oxides,

Charco Redondo mine, Oriente, Cuba....... 87

24. Plan and section of La Yeya mine, Oriente,

Cuba..................................... 90

Figure 7. Plan and section of La Unica mine, Oriente,

Cuba........................................ 85

8. Plan of La Estrella mine, Mafo, Oriente,

Cuba........................................ 89

9. Plan and sections of the Manuel stope No. 5 A,

Bueycito mines, Oriente, Cuba............... 91

III

MANGANESE DEPOSITS OF CUBA

By Charles F. Park, Jr.

ABSTRACT

This preliminary report on the manganese deposits of Cuba is 

based on brief examinations of 160 deposits made during the winter of 1940-41. The report describes the geologic setting and 

classification of the deposits, and discusses their origin. It 

describes individual mines only Insofar as they provide typical 

examples of the ore deposits.

Manganese has been found in every Province of Cuba, but the 

deposits that have been most productive and that contain the 

largest known reserves are in Oriente Province. The Oriente deposits lie in a broad zone about the Sierra Maestra, which consists largely of Eocene volcanic rocks and limestone; with few 

exceptions they are either bedrock deposits in the Eocene rocks 

or the superficial accumulations known as granzon 0

The bedrock deposits are mainly either in tnff or in limestone. Their manganese minerals are mostly the oxides pyrolusite, psilomelane, and manganite. Much "bayate", or jasper, is 

associated with the ores, and zeolites are locally abundant. 

The manganese is thought to have been deposited by warm springs, 

which were active during the last stages of the Eocene volcanism 

that centered in the Sierra Maestra. Textural features show 

that the manganese oxides were in part deposited in open spacesconduits of the spring waters and pore spaces in the rocks--and 

in part by replacement of the rocks. Some of the deposits are 

bedded and appear to be primary accumulations of manganese oxides, presumably derived from spring waters discharged into the 

sea. The lithologic character of these bedded ores indicates 

that they were deposited contemporaneously with the associated 

sedimentary rocks.

The granzon ore consists of nodules or pellets of the manganese oxides found in soil or subsoil near the outcrops of the 

bedrock deposits. It is not concentrated in streams as gravel, 

but appears to be most abundant in nearly level areas or playas 

where surface water stands intermittently or runs off slowly.

Prom 1888 to 1940, the Cuban deposits yielded a total of 

1,237,858 long tons of manganese ore, valued at $21,386,706. 

The 1941 production was expected to be about 225,000 tons, and 

the known reserves are sufficient to maintain this rate of production for several years, providing the present high prices are 

maintained. Production could be increased by opening and improving roads and by introducing efficient mining and milling 

equipment.

75
76 GEOLOGIC INVESTIGATIONS IN THE AMERICAN REPUBLICS, 1941-42

INTRODUCTION

An investigation of the manganese deposits of Cuba was carried on for 5 months during the winter of 1940-41 by the Geological Survey, United States Department of the Interior. The work 

was sponsored by the United States Department of State and was 

made possible by the cooperation of the Cuban Government. Mr. 

Antonio Calvache, Mining Engineer Consultant for the Cuban Ministry of Agriculture, accompanied the writer throughout the 

study, and his knowledge of the deposits, together with his 

familiarity with the country and the people, greatly facilitated 

the work. It would be a pleasure to acknowledge each one of the 

many other enjoyable associations made in the course of the work, 

but a list of all the persons from whom courtesies and cooperation were received would be too long to publish here.

During the investigation, 168 manganese properties and 

groups of properties were briefly examined. The short time 

available did not allow the writer to map any deposit in detail 

nor to make an extensive study of the general geology. This 

paper is, therefore, in the nature of a progress report, for it 

is hoped that the geologic studies in the mineralized region 

will be continued.

The distribution of the principal districts is shown on the 

accompanying index map (pi. 21).

GENERAL GEOLOGY

Most of the manganese ore produced in Cuba has come from 

Oriente Province, which also contains most of the known reserves. 

Deposits are known throughout the area that lies in the southern 

part of Oriente and west of Guantanamo, on both the northern and 

southern slopes of the Sierra Maestra; others lie north and 

northeast of Santiago de Cuba, and there are small bodies north 

and east of Holguin. In Pinar del Rio Province, manganese 

deposits have been found in the lowlands both north and south of
MANGANESE DEPOSITS OP CUBA 77

the Organ Mountains; the best deposits so far developed, lie 

along the northern base of the mountains between Bahia Honda and 

Los Acosta. In Las Villas (Santa Clara) Province, a little ore 

has been developed in the north near Amaro and on the southern 

coast near Trinidad, Deposits on the Isla de Pinos also were 

examined, but they have been so little prospected that it is 

Impossible to evaluate them. The best material seen on the 

island was in the eastern part, near Santa Fe. There are said 

to be undeveloped deposits in the Provinces of Camaguey, Mantanzas, and Habana.

Oriente Province

The Sierra Maestra, which extends along the southern coast 

of Oriente Province, rises abruptly from the Bartlett deep to a 

maximum altitude of about 6,560 feet at Pico Turquino. The 

range is composed largely of Eocene volcanic rocks and limestones dipping in general to the north. Along its southern base 

there are intrusive rocks (the Sierra Maestra bathollth), the

prevolcanic Vinent formation, and older metamorphic rocks. The

I/ 2/ Vinent formation, which is either Cretaceous -' or Eocene =* in

age, consists of quartzite, conglomerate, breccia, lava flows,

and limestones, and Is intruded by granodiorite and other dif3/ ferentiates of Eocene age.-'

The major structure of Oriente, as Hayes, Vaughan, and Spencer first pointed out, is a broad syncline with the long axis 

trending nearly east. The strata dip northward from the Sierra 

Maestra at progressively lower angles, and in the northern part 

of the Province the dips are southward. The synclinal structure

I/ Taber, Stephen, Sierra Maeatra of Cuba, part of the northern rim of 

the Bartlett Trough: Geol. Soc. America Brill., vol. Uj, pp. 575-576, 1931*. 

Singewald, J. T., Jr., and Killer, B. I., The genesis and relations 

of the Daiquiri and Finneza iron-ore deposits, Cuba: AD. Inst. Win. Met. 

Bng. Trans., vol. 53, p. 71*, 19l6.

2/ Schuchert, Charles, Historical geology of the Antillean-Caribbean region, or the lands bordering the Gulf of Mexico and the Caribbean Sea, p. ^93, 

John Wiley & Sons, 1935.

2/ Taber, Stephen, op. clt., pp. 575-576, 591-593-
78 GEOLOGIC INVESTIGATIONS IN THE AMERICAN REPUBLICS, 1941-42

is complicated by numerous minor folds and faults, and reversals 

of dip are rather common. In the north the beds are in contact 

with extensive serpentine masses. The correlation of beds is 

complicated by the abrupt changes in character and the Irregular 

distribution of the volcanic debris.

The manganese-bearing rocks of southern and central Oriente 

are upper Eocene volcanics interbedded with limestones. The 

volcanics consist principally of water-laid basaltic tuffs and 

agglomerates, although in the main Sierra Maestra there are 

flows and dikes, some of which are basaltic and some of which

are rhyolitic. A basal conglomerate and accumulations of

4/ reworked shaly volcanic rocks, probably of Oligocene age,-'overlie the Eocene volcanics.

The basaltic volcanic tuff is generally somewhat altered, 

and contains devitrified glass and ash, quartz, feldspar, olivine, amphibole, pyroxene, and fragments of extraneous rocks, 

particularly limestone. Chlorite and both red and brown iron 

oxides are abundant in the highly altered facies, and locally 

manganese oxides, magnetite, cryptocrystalline silica, zeolites, 

calcite, and minor alteration products are developed. The texture of the tuff differs greatly from place to place. Near the 

northern base of the range, the rocks are predominantly finegrained water-laid tuffs with little coarse debris and very few 

flows. Farther north the volcanic character of the rocks is 

obscure, for the tuffs grade into fine-grained shaly and limy 

beds, locally interlayered with sandstones. The source of much 

of the volcanic debris is apparently near the core of the Sierra 

Maestra, where flows, dikes, and coarse breccias are most abundant.

U/ Hayes, C. 71. , Vaughan, T. W., and Spencer, A. C., Report on a geological reconnaissance of Cuba: In Civil report of Brig. Gen. Leonard flood, Military Governor of Cuba, for igoi. Also Uth Spanish edition, Direc. Montes, 

Minas y Aguas, Habana, Cuba, 1938.

Taber, Stephen, op. cit., pp. 567-620.

Lewis, J. W., Geology of Cubai Am. Assoc. Petroleum Geologists Bull., 

vol. 16, pp. 533-555.
UNITED STATES DEPARTMENT OF THE INTERIOR 

GEOLOGICAL SURVEY

HABANA

BULLETIN 935 PLATE 21

Pinar del

MANGANESE DISTRICTS 

DISTRITOS DE MANGANESO

El Cristo (Quinto, Isabelita)

Ponupo

Sabanilla

Jutinicu

Valle de Manganese

El Iris

Esperansita

Abundancia

Sigua

Manacas

La Estrella, Mafo

La Yeya

Antonio

Pozo Prieto 

15. El Tony-La Gaceta 

16 La Unica 

17. Charco Redondo

Guisa

19. El Cadiz

20. Bueycito

21. Tamayo

22. Ponupo Manacal

23. La Cuca

24. Maceo

25. Lcs Acosta-Francisco

INDEX MAP OF CUBA AND LOCATION OF CUBAN MANGANESE DISTRICTS 

MAPA DE CUBA INDICANDO LOS DISTRITOS DE MANGANESO 452028 O - 42 (Faces p. 78)
MANGANESE DEPOSITS OP CUBA 79

The limestone, which is locally dolomitic, is a dense gray 

or cream-colored rock. It is generally thin-bedded, but in 

places it is massive, Foraminifera of Eocene age are found in 

many places, 'but no detailed study or correlation of the strata 

has ever been made.

Plnar del Rio Province

i 

In Pinar del Rio most of the manganese deposits are in the

shaly San Cayetano formation, but there are small bodies in the 

massive Vinales limestone, which forms the bulk of the picturesque Organ Mountains.

Fossils embedded in a black carbonaceous shale in the San 

Cayetano formation were found at a shaft at La Gloria, a manganese prospect that lies about halfway between San Vincente and 

La Jagua and about a kilometer east of the road. These fossils 

were determined by J. B. Reeside and R. W. Imlay to be perisphincted ammonites of Upper Jurassic age. This confirms Dick67

erson and Butt ' in their assignment of the San Cayetano formation to a Jurassic age. The Vinales limestone lies in isolated 

patches on the San Cayetano formation. According to Dickerson 

and Butt, the Vinales is younger than the San Cayetano and rests

unconformably upon it, but other geologists think that the

7/ Vinales is older than the San Cayetano ' and have suggested that

the Vinales bodies may be remnants of a plate thrust over the

8/ San Cayetano.

5/ Cushman, J. A., The American species of Orthophragmina and Lepidocycllna: U. S. Geol. Survey Prof. Paper 125, pp. 39-105, 1920.

6/ Dickerson, R. E., and Butt, W. H., Cuban Jurassic: Am. Assoc. Petroleum Geologists Bull., vol. 19, pp. 116-118, 1935.

De Oolyer, B., The geology of Cuban petroleum deposits: Am. Assoc. 

Petroleum Geologists Bull., vol. 2, pp. 136-lUg, 1918.

2f Metcalf, R. J., Discussion of Cuban Jurassic: Am. Assoc. Patroleum 

Geologists Bull., vol. 16, pp. 553-55U, 1932.

8/ Palmer, R. H., personal communication 19*41.

452028 O - 42 - 2
80 GEOLOGIC INVESTIGATIONS IN THE AMERICAN REPUBLICS, 1941-42 

Las Villas Province and Isla de Pinos

The general geology of Las Villas (Santa Clara) Province 

near the manganese districts has been described briefly by Rutten 'and by Thiadens, 'and descriptions of the Isla de Pinos 

have been published by Hayes 'and by Llaguno. ' The rocks of 

Las Villas and of the Isla de Pinos are principally schists,

shales, and limestones similar to the formations of Pinar del

13/ Rio anil Habana 'Provinces,,

ECONOMIC GEOLOGY 

Mineralogy

Manganese minerals, Manganese ores of both chemical and 

metallurgical grades are mined in Cuba, but metallurgical ores 

are by far the more abundant. The two types occur together, and 

as they cannot be distinguished with certainty in the field no 

effort was made to study them separately»

The ores in general seem to be simple in composition. The 

principal ore minerals are pyrolusite (MnOp), psilomelane 

(MnOo.MngO.,) containing up to about 5 percent barium, and manganite (MiigO-.HoO). Other minerals of little or no economic value 

that occur in the deposits are the silicates braunite 

(3 Mng03 .MnSi03 ) and orientite UCaO^MngO-joSSiOg^HgO) and the 

gray, brown, or black, vitreous, amorphous or cryptocrystalline 

material included under the name of neotocite. Piedmontite, a 

manganese-bearing epidote, is associated with manganese oxides

2/ Rutten, M. G., Geologla de la parte Norte de la Provlncla de Santa 

Clara (.Traducclon por los Sres. E. V. Perez y Jorge Brodemwnn): Dlrec. 

Montes, Mlnas y Aguas, Cuba, Bull. 16, pp. 5-55, 1938.

10/ Biladens, A. A., Oeologia de la parte Sur de la Provlncia de Santa 

Clara (Traduccion por los Sres. E. 7. Perez y Jorge Brodennann): Dlrec. 

Montes, Minas y Aguas, Cuba, Bull. IS, pp. 5-56, 1939.

ll/ Hayes. C. ff., Vaughan, T. W., and Spencer, A. C., op. clt. pp. 112- 

117, 1901.

12/ llaguno y de Cardenas, Pablo, La Isla de Pinos, pequeno bosquejo 

historico de las Isla y sus aguas medico medicinales: Habana. No date 

given.

13/ Brodermann, Jorge, Detennlnacion geologica de la Cuenca de Ventoi 

Bevlsta de la Socledad Cubano de Ingenleros, vol. 3U, pp. 272-315, iglJO.
MANGANESE DEPOSITS OP CUBA 81

from Sigua, Oriente, and from a deposit near the city of Camaguey. A sample of oxide ore from the Lucrecia prospect near

14/ 

Amaro, Las Villas, contains 0.25 percent cobalt, and prompts

the suggestion that the ores should be tested for small quantities of metals, particularly cobalt and tungsten, that might be 

recovered as salable byproducts.

The manganese oxides range in color from brilliant silver 

gray to sooty black. The hardness of the ore varies widely; 

much of it is soft, but some specimens will scratch steel. The 

ore is commonly friable, botryoidal, powdery, or fibrous, and is 

exceedingly porous.

Other minerals. Brown, red, and in a few places gray or 

black "bayate" or Jasper (cryptocrystalline silica) is a common 

companion of the manganese ores, particularly those in tuff beds. 

In the ores associated with limestone in the Los Negros-Charco 

Redondo-Guisa areas in Oriente^ Jasper is commonly present in 

small nodules or pockets, but in general it is much less abundant in these ores than in the ores associated with tuff. The 

Jasper is commonly associated with faults and forms the crests 

of arches and domes, from which the beds dip away in all directions. As the Jasper weathers and disintegrates less readily 

than the enclosing tuffs, limestones, and shales, the larger 

bodies crop out as knobs or hills, and fragments of it are conspicuously scattered over the surface. The best ore near the 

domes is commonly covered with a rubble of Jasper and with other 

surface debris, because it is in the softer tuff beds next to 

the Jasper. In many of the domes, manganese-bearing velnlets 

and pockets are found in the Jasper, and locally these are mined. 

The domes are numerous in the El Cristo-Alto Songo region,

Orlente, where they include such well-known deposits as the

15/ 

Ponupo (2), ' Isabelita (1), Sabanilla (3), and Jutinicu (4).

Analysis by Michael Fielecher, Geological Survey, United States 

Deparnent of the Interior.

15/ Numbers in parentheses refer to those used on the map (pi. 21).
82 GEOLOGIC INVESTIGATIONS IN THE AMERICAN REPUBLICS, 1941-42

In other deposits of Oriente, such as Abundancia (8) and Ponupo 

Manacal (22), the jasper is concentrated in irregular masses 

along faults, and the manganese ore is richest next to jasper 

and decreases in grade away from it. In Pinar del Rio, gray or 

black jasper resembling chert forms beds, generally less than 

6 inches thick, or nodules distributed parallel to the bedding. 

This material seems to be most abundant near manganese deposits, 

although it is also present elsewhere. In Las Villas Province 

near Amaro, manganese oxides cement white or light-gray chert 

fragments in a breccia zone along a limestone-schist contact.

The Jasper is commonly cut by veinlets of manganese oxides, 

but in some places manganese oxides are cut by veinlets of jasper o This is interpreted to mean that the jasper and-manganese 

oxides were deposited in part concomitantly from the same solution. As pointed out by Spencer, 'the fact that Jasper and 

manganese oxides are concentrated along the tops of arches and 

domes indicates that they probably were derived from ascending

solutions.

17/ Many ores contain abundant zeolites. Larsen 'found anal18/ cite, heulandite (?), and laumontite (?), and Hewett 'found,

in addition to analcite and laumontite, coarsely crystalline 

pectolite and chabazite in veinlets crosscutting the manganese 

oxides of the Bueycito ores. The zeolites, particularly where 

they are coarsely crystalline, are thought to have been deposited from warm water, as a result of hydrothermal action that 

continued after the deposition of the manganese oxides.

Black calcite, the color of which is caused by finely 

divided particles of manganese oxides, is widespread. Rhodochrosite, if present at all, is exceedingly rare.

l6/ Hayes, C. V., Vaughan, T. W., and Spencer, A. C., op. cit., p. 6U.

Tf/ Larsen, E. S., in Burehard, X. F., Manganese-ore deposits in Cuba:

Am. Tnst. Min. Met. Eng. Trana., vol. 63, p. 60, 1920.

IS/ Hewett, D. 7., personal communication,
MANGANESE DEPOSITS OP CUBA 83

The manganese silicates bementite and neotocite are widespread, occurring in small quantity in many deposits, but there 

are many deposits in which they have not been found.

Unoxidized pyrite is associated with manganese oxides in 

several mines, such as the Ponupo.

The presence of chlorite and possibly glauconite causes many 

tuff beds in Oriente to be bright green. The green color is 

strikingly conspicuous in the beds a few Inches below ore, 

though it is also present elsewhere in the tuffs.

Most manganese deposits are bordered or overlain by red 

tuffs and limestones, and the miners commonly associate red coloration with the presence of manganese oxides nearby. Similar 

red rocks occur, however, at many places where no manganese 

deposit is known nearby. The red rocks near the deposits may 

have been formed at about the same time and by the same solutions as the manganese oxides, but they are of questionable 

value as an aid to prospecting because they resemble the products of ordinary weathering.

Classification of the deposits

Ore deposits may be classified in various ways, depending on 

what is known concerning them and the purpose to be served by 

the classification. If the purpose is to interpret genesis, 

much information concerning the minerals and their relations, as 

well as their geologic environment, is needed. If, however, the 

purpose is to facilitate exploitation, emphasis may be placed 

upon outstanding elements of form and rock environment The 

present study has yielded considerable information about the 

geologic environment and the form and mineralogy of the manganese deposits, but the deposits have not yet been studied with 

sufficient thoroughness to permit the formulation of a comprehensive genetic scheme. At this time, therefore, it seems 

advisable to present a classification of the deposits based
84 GEOLOGIC INVESTIGATIONS IN THE AMERICAN REPUBLICS, 1941-42

primarily upon rock environment together with some consideration 

of the form of the workable deposits of manganese oxides.

Most of the manganese deposits fall into three principal 

classes:

1. Deposits in tuff. Examples: The mines near El

Cristo (1) and the Bueycito mines (20), Oriente.

2. Deposits in limestone. Examples: La Unica mine 

(16) and Charco Redondo mine (17), Oriente.

3. Granzon, or surficial layers of manganlferous granules and pellets in soil. Examples: La Gaceta 

mine (15), Oriente, and La Cuca mine (23), Pinar 

del Rio.

Some deposits do not properly fit into any one of .the three 

main classes, and they are, for convenience, described together 

as "miscellaneous deposits "

Deposits in tuff. The deposits in tuff are the most abundant in Oriente, and they occur throughout the mineralized area 

of that Province. These deposits consist of grains, nodules, 

pockets, and veinlets of manganese oxides irregularly distributed through beds of altered tuff. Their form is essentially

tabular. In many of the ore bodies the matrix is soft, soapy,

19/ pinkish or reddish material, described by Larsen ' as kaolinite (?), with some of the zeolites analcite, heulandite (?), and 

laumontlte and some calcite. At such properties as the Quinto 

pit (1) and the Ponupo (2) mine, Oriente, entire beds up to 

20 feet or more in thickness are mined over considerable areas, 

but most of the bodies are locally lenticular or of irregular 

shapes. In most beds the ore grades laterally into low-grade 

mineralized tuff, but some contacts between ore and the enclosing tuff are abrupt, and there the rocks within about a foot of 

the ore are almost free of manganese oxide. The tops and bottoms of ore-bearing beds are sharply defined undulating or plane 

surfaces. In a few places the ore bodies are limited by faults 

or slips.

Larsen, E. S., in Burchard, E. 7., op. cit.
MANGANESE DEPOSITS OF CUBA 85

The deposits in tuff are larger and of more uniform composition, in general, than those in other environments, and consequently they have yielded most of the manganese produced in Cuba.

SECTION 

PEPFIL

LOWER LEVEL 

'riVEL INFERIOR

PLAN

PL A f\TO

Modified after F. D. Fbgliuchi 

Original de FD. flayliucAi, modificado

Figure 7. Plan and section of La Unica nine, Oriente, Cuba.

Deposits in limestone. The deposits in limestone occur

chiefly in Oriente, on the northern flank of the Sierra Maestra 

between Contramaestra and Guisa, but similar deposits have been
86 GEOLOGIC INVESTIGATIONS IN THE AMERICAN REPUBLICS, 1941-42

prospected in Pinar del Rio and near Trinidad in Las Villas. A 

few ore bodies such as that mined at La Unica (16) (see fig. 7) 

are large, well-defined lenses, but generally the limestone contains irregularly distributed stringers of manganese oxides, 

together with pockets or small lenses of ore formed where the 

stringers widen or coalesce (pi. 22, A). In some places, manganese oxide stringers cement limestone brecciaj in other places, 

fragments of manganese oxides in broken veinlets and In groups 

of broken fibers are cemented by limestone (pi. 22, B). At the 

Charco Redondo (17), Oriente, and other nearby .deposits, layers 

of manganese oxides up to 4 feet thick lie between limestone 

beds. These oxide layers contain a few inclusions of tuff and 

other materials, and some of them are remarkably continuous. At 

Charco Redondo a bed 6 inches to 2 feet thick has been traced by 

means of trenches and pits for more than a mile along the strike.

Except for a few large lenses, some of which contain 25,000 

tons or more of ore apiece, the manganese oxide bodies in limestone are small, and few yield more than 100 tons of ore.

Granzon, Granzon is a term applied to ore consisting of 

nodules or pellets of manganese oxide in soil or subsoil. These 

pellets, most of which are less than an inch in diameter, are 

generally made up of concentric layers of oxides (pi. 23, A). 

To have commercial value they usually should make up more than 

10 percent of the bulk of the soil. The best granzon ore is 

free from pebbles and from nodules of minerals other than manganese oxides, so that it yields a high-grade concentrate when 

washed. In some localities, particularly in Pinar del Rio, the 

granzon contains iron oxides and the manganese-rich pellets 

grade into pellets of iron oxides without manganese that are 

very similar to them in appearance. For this reason, careful 

sampling of granzon ores in advance of mining is necessary.

Granzon is found throughout the manganese-bearing region of 

Cuba, principally near the outcrops of other kinds of ore. It
GEOLOGICAL SURVEY BULLETIN 935 PLATE 22

A. MANGANESE OXIDE POCKET IN LIMESTONE, EL TONY PROSPECT, ORIENTE, CUBA. 

The hammer handle is 18 inches long.

B. MANGANESE OXIDE FRAGMENTS IN LIMESTONE, CHARCO KEDUNDO Mli\E,

ORIENTE, CUBA.

The hammer is on a layer of solid manganese oxides.
GEOLOGICAL SURVEY 

A. GKANZON FROM LA CUCA MINE, PINAR 

B. VEINLETS OF TUFF IN MANGANESEE OXIDES, CHARCO R
MANGANESE DEPOSITS OP CUBA 87

is not concentrated in streams as gravel but appears to be 

mostly mixed with soils at or near the surface in nearly level 

areas, or in playas where surface water stands Intermittently or 

runs off slowly. In some deposits in Pinar del Rio and the Isla 

de Pinos, manganese oxide pellets are cemented together into 

cobbles or boulders which, if numerous, may be strewn over the 

surface.

Most individual granzon deposits yield less than 1,000 tons 

of concentrate, although some bodies, such as the one at La Cuca 

mine (23), Pinar del Rio, are estimated to contain more than 

50,000 tons. The ore is easily recovered with a small capital 

outlay, and the concentrates are of better grade than the other 

varieties of ore. For these reasons, granzon is much sought and 

is commonly the ore first mined in a district 0

Miscellaneous deposits.--The surface outcrops of a few mineralized bodies, particularly in Pinar del Rio, are marked by 

soft black powder or black soil, but not by granzon. In Pinar 

del Rio, and to a lesser extent in Oriente, layers of finegrained, compact, high-silica, manganese-bearing rock are found, 

commonly parallel to the bedding. As such rock requires expensive beneficlation, these lodes have been little explored. Many 

are less than a foot wide, and many would be relatively costly 

to mine because of their steep dip. The ores in the Maceo prospect (24), near Vinales, Pinar del Rio, and similar properties 

consist largely of manganese silicates with small amounts of 

manganese oxides; other bodies, such as those near Bahia Honda 

in Pinar del Rio and near Sigua (9) in Oriente, contain some 

silicates but appear to be mainly fine-grained mixtures of manganese oxides and silica. Some of the siliceous deposits, such 

as those near Bahia Honda, contain patches of low-silica oxides 

that are large enough to be worth exploring.

At the Esperansita prospect (7), about 16 miles north of 

San Luis, Oriente, fragments of manganese oxides are scattered
88 GEOLOGIC INVESTIGATIONS IN THE AMERICAN REPUBLICS, 1941-42

Irregularly through a bed of conglomerate 20 to 30 feet thick, 

and at some places in this conglomerate the matrix also consists 

In part of manganese oxides.

At the Antonio mine (13), near Los Negros, Oriente, manganese oxides partly fill caves in limestone, and cave deposits In 

limestone are known in other localities.

Relation to bedding

In many tuff deposits the layers of manganese oxide, though 

apparently parallel to the bedding, actually are inclined at a 

small angle to it. The tuff is replaced by the manganese oxides, 

as is shown by corroded remnants of rock and by relict structures and textures in the ores. In the same deposits, however, 

fragments of veinlets or of crystal groups lie with their long 

axes parallel to bedding planes. This mode of occurrence is 

interpreted to mean that some manganese oxide was deposited with 

the tuff, but that manganese-rich solutions continued to circulate through the bdtls after sedimentary accumulation stopped. 

Evidence that the manganese oxides were deposited before the 

tuff was consolidated can be seen at the Charco Redondo mine (17), 

where there are small veinlets of tuff in manganese oxides 

(pi. 23, B).

Many of the manganese deposits are at or near contacts 

between tuff beds, or between tuff and schist or limestone. 

Some deposits, for example La Estrella mine (see fig. 8) and 

La Yeya mine (12) (see pi. 24), are in the tuff, whereas others, 

such as El Cadiz (19) near Guisa, Oriente, are in both tuff and 

limestone. Some of the manganese-bearIng layers in limestone 

have a limy matrix, others contain small quantities of tuff and 

pinkish zeolites, and nodules of brown jasper. There is every 

gradation from the bedded ores In limestone to the characteristic ores In tuff. Manganese ores are so generally concentrated 

along contacts of tuff and limestone and near the bottoms of the
MANGANESE DEPOSITS OP CUBA 89

limestone beds as to indicate that in places the carbonate 

caused the deposition of manganese oxide.

The bedded ores also show features that indicate contemporaneous deposition of manganese oxides and limestone. At Charco 

Redondo sharks teeth occur in clay seams in the ore, and similar 

teeth are reported from deposits near Guisa. At Charco Redondo 

a bed of manganese oxide and impure limestone contains undeformed rods that suggest worm burrows, and rhythmically banded

All drifts in ore,- 

limestone above, 

Todas las galenas/ 

en el mineral, ' 

caliza. encima.

All ore in tuff bed 

Tbdo el mineral en. un 

estrato de toba

.Limestone blocks in ore 

]Bloc/ues de caliza en mineral

,5 feet ore Spies de mineral

50

Shaft 20 feet deepi 

lower 15 feet ore 

Pozq de BO pies de profundidad/ 

\J5 pies de mineral en el fondo

\

0

I

Limestone block 

BLoaue de caliza

5 feet ore

5 pies de mineral

IOO Teet 

Pies

Figure g. Plan of La Estrella mine, Mafo, Orients, Cuba.

nodules and layers are common,, These and similar deposits 

appear to be primary accumulations of manganese oxides in a limy 

ooze on the bottom of a shallow sea floor.

At Charco Redondo a limestone that overlies a bed of solid 

ore contains, near its base, many fragments of manganese oxides 

and a few pieces of volcanic rocks. No evidence of faulting was 

seen in the well-exposed contact zone (pi. 22, B). The material 

strongly resembles an intraformational conglomerate containing
90 GEOLOGIC INVESTIGATIONS IN THE AMERICAN REPUBLICS, 1941-42

fragments from the underlying bed of ore. Similar conglomerate 

has also been noted in the Guisa area.

Thin persistent beds of oxides are common in the limestones 

of the Los Negros, Charco Redondo, and Guisa areas. At Charco 

Redondo, one such bed with a maximum thickness of 2 feet in its 

middle part has been followed along its outcrop for more than a 

mile. It thins out in both directions to about 6 inches. Such 

a bed probably formed as a sediment on the sea floor, the manganese being contributed by spring waters.

Relation to faults

Faults are abundant throughout the mineralized areas, and 

have evidently acted as conduits for ascending solutions. In 

some mines the best ore occurs along faults or fault zones (see 

fig. 9), but in other deposits, such as that of the Sultana ore 

body at Ponupo (2), there is no convincing evidence that the ore 

bodies are related to faults. Most of the faults, however, are 

of small displacement, and many die out in the nearby overlying 

and underlying beds,

Origin of the bedrock deposits

20/ Spencer, 'who first studied the Cuban deposits, thought

that most of the oxides were of hydrothermal origin. He said:

their (manganese ores) having been deposited by ascending solutions, and together with the fact that the jasper is probably a 

hot spring deposit warrants the supposition that the ores were 

formed by the action of hot water having its origin at a considerable depth below the surface of the earth upon certain beds of 

calcareous rocks particularly suited by their composition to 

being replaced by the chemical constituents held in solution.

22 / 

In general, St. Clair agrees with Spencer. He says:

The ores were deposited by ascending warm solutions 

approaching the hot spring type.* * *The theory that manganese 

oxides formed the primary ore* * -^eliminates the difficulty presented by the complete absence of carbonates* * *and by the

20/ Hayes, C. 17., Vaughan, T. ff., and Spencer, A. C., op. cit., p. 65.

?T/ Parenthetical words inserted by the writer.

22/ St. Clair, David, unpublished memorandum, dated May 1,
GEOLOGICAL SURVEY BULLETIN 935 PLATE 24

Po,

SECTION 

PERFJL

'Fault contact 

/ Contacto y folio. 

t*.

Limestone and

volcanic breccia

Caliza y brecha. volcdnica.

Limestone in wall of upper level)

shaft 44 feet deep 

Caliza en. la. pared del nivel superior,

pozo * # pies de profundidad \ \

V \

\ \ 

\ \

bn't \

\ \

\ \

\ \

\ \

1 v v" 

/* x

1 1 *

!\ v

f \

Ish

f

\br

EXPLANATION

Lower level _._._

Intermediate level 

Upper level 

Open CUt -r-r^-T.

Ore 

Mineralized rocK « -. 

Volcanic breccia br 

Limestone Is

35 0

1 , 1 , 1 1

\ \

\ \

\ \

'. \

EXPLICACION .

Nivel inferior \

Nivel intermedia \ \ 

Nivel superior br\ \ Ttijo \ > Mineral ' \

Roea mineralizada \ \ Brecfia volcamica. \ \ Caliza \ \

\ \ br

PLAN

PLANO

50

1 1 1

lootf*1 1 Ple3

PLAN AND SECTION OF LA YEYA MINE, ORIENTE, CUBA 

PLANO Y PERFIL DE LA-MINA LA YEYA. ORIENTE. CUBA
MANGANESE DEPOSITS OP CUBA 91

existence of primary pyrite and zeolite in close connection with 

the ore.

23/ 

Norcross ' considered the ore to be hydrothermal He said:

Manganese mineralization in Oriente Province is of regional 

character and probably had its inception in hydrothermal activity incidental to this intrusive epoch (the intrusion of the 

Sierra Maestra granodiorite bathollth).

Water 

Agua 

SECTION 

PEFLFIL

Water

Agua ~ J

EXPLANATION EXPLICACfON 

Manganese Mn Manganese 

Fault fa.Uo.

25 ( SO Feet 

'Pies

Figure 9. Plan and sections of the Manuel stope No. 5 A, Bueyclto mines,

Oriente, Cuba.

24/- 

Hewett ' considers that such deposits as the bedded oxides

of Charco Redondo are sedimentary in origin, but he believes 

that all of the hydrous silicates, zeolites, and silica in the 

region are products of widespread hydrothermal activity, and

2J2/ Norcross, ?. S., Jr., Development of the low-grade manganese ores of 

Cuba: Am. Inst. .Mln. Met. Eng. Tech. Pub. llgg, p. 3, 19-UO. 

2U/ Hewett, D. P., personal communication, igUl.
92 GEOLOGIC INVESTIGATIONS IN THE AMERICAN REPUBLICS, 1941-42

that some of the manganese oxides also were deposited by hot

waters.

25/ Burchard ' in 1920 suggested that

The proximity of volcanic rocks to the manganese-bearing 

areas in Oriente Province, and the broader structural relations 

of the region suggest the possibility that the manganese was 

derived from volcanic rocks of the Sierra Maestra, transported 

by artesian waters and deposited, together with silica as masses 

of manganiferous jasper in joints, fissures, and cavities in the 

limestone and other rocks in the local anticlines of the basin, 

as well as along the beds of the more porous tuff.

The small deposits of manganese oxides discovered in recent 

years near the crest of the Sierra Maestra are difficult to 

explain as products of circulating artesian waters related to 

the present topography.

The deposits have none of the characteristics of superficial 

accumulations of manganese oxides concentrated by weathering. 

Cuba is subjected to alternating seasons of heavy rainfall and 

drought, and much of the land is deeply weathered. Under such 

conditions superficial concentration by ordinary weathering 

processes should be expected. Such deposits, however, are 

unusual. Granzon and soft black powdery soil derived from 

nearby bedrock deposits are widely distributed, but accumulations of residual manganese oxides derived, like bauxite and 

lateritic iron ores, from the decomposition of large rock masses 

are unknown.

In the best-exposed deposits, moreover, such as those near 

El Cristo, no evidence of enrichment related to the present surface has been recognized below the few feet of granzon on the 

outcrop. At the Qulnto pit, beds 10 to 20 feet thick have been 

explored to a depth of more than 300 feet, or for about 1,200 

feet down the dip. The thickness, grade, and character of these 

beds do not change appreciably with depth.

Pyrlte is found near several ore bodies, both above and 

below them. The presence of unaltered pyrite in porous beds

Burchard, S. P., op. clt., pp. 56-57.
MANGANESE DEPOSITS OP CUBA 93

directly overlying manganese oxides indicates that ordinary 

processes of oxidation have not been active since the formation 

of the pyrite.

The deposits of manganese oxides in caves which are found at 

several places in the limestone area may or may not be residual. 

At the Antonio mine (13), near Los Negros, stalactites of calcium carbonate project through layered accumulations of manganese oxides which, together with a few thin beds of red or brown 

clay, partly fill the cave. As the limestones are extremely 

cavernous and surface waters move rapidly and easily through

them, 3ome of the cave deposits are thought to be residual. On

 

the other hand, deposits that appear to be cave fillings

directly overlie and seem to grade into ores typical of the 

deposits In tuff. As ascending warm waters would take advantage 

of any open channels, it is possible that some of the manganese 

In the caves was deposited from circulating warm waters.

It is concluded that the manganese of the deposits of 

Oriente, excluding the granzon, was derived from warm springs. 

It is believed that the warm waters rising along conduits deposited manganese oxides at favorable places along the conduits and 

in adjacent porous beds, partly by direct deposition in openings 

and partly by replacement of tuff or limestone; it is also 

believed that warm water reaching the sea deposited manganese 

oxides as a primary sediment. Deposition is thought to have 

taken place during the last stages of the Sierra Maestra volcanic activity, in late Eocene and possibly early Oligocene 

times. The largest deposits were formed in a broad zone around 

the center of greatest volcanic activity. The ultimate source 

of the manganese is not known.

Although this explanation is advanced particularly.for the 

deposits of Oriente, a similar origin is considered to be likely 

for the deposits in Pinar del Rio and Las Villas Provinces. The
94 GEOLOGIC INVESTIGATIONS IN THE AMERICAN REPUBLICS, 1941-42

deposits in. other areas are so Imperfectly known that no definite conclusions regarding their origin are warranted.

I/

Production of manganese ore from Cuba

Year

1888-1896. .......... o ..............

1897. .... o .........................

1898. ..............................

1899. . .............................

1900. . .............................

1901. ..............................

1QO?

1903. ..............................

TQO4

1905. . .............................

1906. ..............................

1907. ...... o ...................... o

1908. ..............................

1 QOQ

1910. ..............................

TQ11

-\Q~\P

1913 ...............................

1 Q1 4

1915. ..............................

1916. ..............................

1QT7

1918. ..............................

1919. . .............................

1 QPO

1921...............................

1 QP?

1923. ..............................

IQP4

1925. ..............................

1926. ..............................

1 QP7

1928. ..............................

1QPQ

1930. ..............................

1931. ..............................

1932. ..............................

T Q**^

1934 ...............................

1935. . .............................

1936. . .............................

1937. ..............................

1938. ..............................

1939 ...............................

1 Q4O

Total. ................. o .......

Long tons =/

3/ 77,228

4/ fi QQ?

1,600

16,359

20,582

21,627

36,294

17,721

16,239

6,489

11,701

30,006

1,469

2

Qcn

2

0

0

0

0

5,141

30,563

44 R1 T

Dp 074.

i^ c; ^on

8 04.7

34

12,568

9,062

23,065

1 P 747

14 IT?

8,976

3,180

2,667

? O71

3,804

6,749

28,257

63,743

43,955

37,912

122,937

131,422

105,936

130,646

1,237,858

Value £/

ftfiQR ^Q 1*

81,126

8,026

221,785

259,348

307,084

285,571

111,670

RO Q74'

35,049

117,050

PfiP R47

13,489

11,800

26

0

0

0

0

CO AK1*

514,184

612,413

2

7C1 T Q-Z

1 4^^ POP

Pfifi 744

fi7Q

89,677

137,016

"^47 fl74

pc-z -i-i c

224,523

141,836

60,402

32,654

 ip -IT 7

5/ 19,891

 111,770

430,906

965,610

700,493

521,809

2,185,800

2,242,425

1,689,547

3,059,735

21,386,706

I/ Ore containing 35 percent or nore manganese.

2/ Figures from the Bureau of Foreign and Domestic Commerce.

V Exports from Cuba.

I

Imports Into the United States from Cuba. 

This is the figure recorded, but it seems low.
MANGANESE DEPOSITS OP CUBA , 95 

Production

Prior to January 1, 1941, Cuba had produced, according to 

the best available records, 1,237,858 tons of manganese ore, 

containing 35 percent or more of manganese and having a value of 

$21,386,706. Nearly all this ore was mined in Oriente Province. 

The preceding table gives the production by years.

Economic factors

Manganese mining in Cuba has in the past been more or less 

irregular when prices rose the mines were opened and when 

prices dropped the mines were abandoned. With a few exceptions 

the mines are owned and operated by individuals and small companies with little capital, and even owners with ample capital 

have been loath to make large investments because of the uncertain future of the industry. Many efforts, a few adequately 

financed, have been made to establish the industry on a permanent basis; but all these have failed, principally because of 

the low grade and pockety nature of the ore, high costs of 

mining and transportation, and lack of a cheap method to improve 

the grade of the ores. The recently developed open-pit mining 

methods and the flotation and nodulizing plant of the Cuban 

Mining Co. at El Cristo will, it is hoped, form a stabilized 

basis for expanding the industry. With the exception of the 

Cuban Mining Co. and a very few others, the mines producing 

Cuban manganese are mining at high cost and generally with a low 

margin of profit, and only if drastic reduction in cost can be 

effected at these mines will it be possible for them to operate 

during normal times.

The first need of the mining regions is improved transportation. Many mines are connected with the Central Highway or the 

railroad only by trails and unimproved roads that are poor when 

dry and Impassable when wet. Ore is hauled from many properties
96 » GEOLOGIC INVESTIGATIONS IN THE AMERICAN REPUBLICS, 1941-42

on muleback, a costly and unsatisfactory method because production is limited by the number of mules available and the state 

of the weather. Thus there is urgent need of well-drained and 

graded roads, passable for trucks in wet and dry weather. 

Transportation is handicapped, moreover, by high freight rates 

and irregular railroad and boat services.

Method of mining.' Except for the large bodies of low-grade 

ore which are being extracted systematically, the manganese 

deposits are being mined from small holes and irregular workings. 

As most of the deposits are irregular and pockety, this practice 

of following the ore is wise; many long adits and deep shafts 

have been driven in vain attempts to cut ore in depth. Mining 

machinery is expensive, and even second-hand equipment is hard 

to get; miners, therefore, with a few exceptions, have no other 

mining equipment than picks, shovels, and wheelbarrows, and 

where hoisting is necessary, buckets and windlasses. Loading 

and storage bins are practically unknown. The ore is generally 

moved by hand several times before it reaches the railroad, and 

each time the friable ore is moved, much is lost in .fines. Also, 

as the ore is very porous, it absorbs and retains water whenever 

stored in the open during rainy weather.

Method .of concentration. Most of the ore, of whatever kind, 

must be concentrated. This is generally done by the slow process of hand-sorting: the ore is dumped on the ground, the 

larger pieces are broken with small hammers, and the high-grade 

material is picked out and piled at one side or put into sacks. 

Several mines use inexpensive log washers to remove clay from 

soft ores and granzon, and where water is plentiful this method 

seems to give good results, though the fines are generally lost. 

During the dry season some granzon is recovered by dumping soil 

and pellets on a £-inch screen, where they are dry-scrubbed by 

hand with wire brushes until the pellets are clean. At a few 

properties, efforts are made to concentrate ore by Jigging, but
MANGANESE DEPOSITS OF CUBA 97

such operations are all handicapped by old and inadequate equipment and by lack of trained personnel. The modern flotation and

nodulizing plant of the Cuban Mining Co., designed to handle

26/ about 1,200 tons a day, has recently been described. '

Future of the deposits

It was estimated that Cuba would produce in 1941 about 

225,000 tons of ore containing 38 percent of manganese or better, 

including sintered fines from the Cuban Mining Co. plant. Sufficient ore is available to maintain present production for 

years if present high prices are maintained. Production could 

readily be increased by opening roads into favorable but at 

present inaccessible regions, such as Pozo Prieto, south of 

Baire, and Valle de Manganeso, northeast of Alto. Songo.

26/ Horcross, 7. S., Jr., Development of the low-grade manganese ores of 

Cuba: An. Inst. Min. Met. Eng. Tech. Pub. 1188,

O