Manganese Contents of Some Sedimentary Rocks of 

Paleozoic Age in Virginia 

By ERIC R. FORCE and LESLIE j. COX 

A. Manganese Contents of Some Lower Paleozoic Carbonate Rocks of Virginia, 

by Eric R. Force 

B. Manganese Contents of Some Rocks of Silurian and Devonian Ages in Northwest 

Virginia, by Leslie J. Cox 

U.S. GEOLOGICAL SURVEY BULLETIN 1916 
U.S. DEPARTMENT OF THE INTERIOR 

MANUEL LUJAN, Jr., Secretary 

U.S. GEOLOGICAL SURVEY 

Dallas L. Peck, Director 

Any use of trade, product, or firm names in this publication is for descriptive purposes 

only and does not imply endorsement by the U.S. Government 

UNITED STATES GOVERNMENT PRINTING OFFICE: 1991 

For sale by the 

Books and Open-File Reports Section 

U.S. Geological Survey 

Federal Center, Box 25425 

Denver, CO 80225 

Library of Congress Cataloging in Publication Data 

Force, Eric R. 

Manganese contents of some sedimentary rocks of Paleozoic Age in Virginia I 

by Eric R. Force and Leslie J. Cox. 

p. em. ~ (U.S. Geological Survey bulletin; 1916) 

Includes bibliographical references. 

Supt. of Docs. no.: I 19.3:1916 

1. Rocks, sedimentary~ Virginia~Analysis. 2. Geology, Stratigraphic~ 

Paleozoic. 3. Manganese ores~Geology~Virginia. I. Cox, Leslie j. 

II. Title. Ill. Series. 

QE75.B9 no. 1916 

[QE471] 

557.3 s--dc20 

[553.4'629'09755] 90-22802 

CIP 
CONTENTS 

[Letters designate the chapters] 

A. Manganese Contents of Some Lower Paleozoic Carbonate Rocks of Virginia, 

by Eric R. Force 

B. Manganese Contents of Some Rocks of Silurian and Devonian Ages in Northwest 

Virginia, by Leslie J. Cox 

Contents Ill 

Chapter A 

Manganese Contents of Some Lower 

Paleozoic Carbonate Rocks of Virginia 

By ERIC R. FORCE 

Manganese in Shady Dolomite and Knox 

Group rocks that underlie supergene 

manganese deposits 

U.S. GEOLOGICAL SURVEY BULLETIN 1916 

MANGANESE CONTENTS OF SOME SEDIMENTARY ROCKS OF PALEOZOIC AGE 

IN VIRGINIA 

CONTENTS 

Abstract Al 

Introduction Al 

Supergene Deposits Al 

"Parental" Carbonate Bedrock A3 

Shady (Tomstown) Dolomite and Underlying Quartzite A3 

Knox Group A3 

Study Methods A4 

Manganese Contents A4 

Shady Dolomite and Underlying Quartzite A4 

Harpers Ferry Area A4 

Shenandoah River Section AS 

Buchanan Area AS 

Austinville-Ivanhoe Area AS 

Marion Area A6 

Summary A6 

Knox Group A 7 

Round Hill A 7 

New River Section A7 

Tazewell Area A 7 

Summary AS 

Conclusions AS 

References Cited AS 

FIGURES 

1. Index map showing locations of areas of sample collection, former manganese mining districts, and the outcrop belt of Shady Dolomite A2 

2. Graph showing manganese and iron contents of samples of Shady Dolomite A 7 

TABLES 

1. Manganese and other elemental contents of the Harpers Ferry section A4 

2. Manganese and other elemental contents of the Shenandoah River section AS 

3. Manganese and other elemental contents of the Fosters Falls and Galena Creek 

sections A6 

4. Manganese and other elemental contents of the Sugar Grove section A6 

5. Manganese and other elemental contents of the New River section, Knox 

Group A7 

6. Manganese and other elemental contents of the Wittens Mills section, Knox 

Group AS 

Contents VII 

CHAPTER A 

Manganese Contents of Some Lower Paleozoic 

Carbonate Rocks of Virginia 

By Eric R. Force 

Abstract 

The lower Paleozoic carbonate formations of Virginia 

have an apparent potential for shallow-marine sedimentary manganese deposits. Where those formations form 

the substrate of supergene manganese deposits, they 

were analyzed for manganese and other elements in this 

reconnaissance investigation. The highest primary manganese content encountered, in laminar limestones at the 

base of the Shady Dolomite, was only 0.3 percent. The 

great disparity in manganese contents of bedrock and 

overlying supergene deposits is not matched by similar 

disparities for other insoluble elements, suggesting that 

supergene enrichment was not simply a result of residual 

enrichment. Probably manganese in solution, derived 

from a number of sources, was geochemically trapped in 

the overburden above certain reactive units. Within this 

overburden, manganese was further concentrated in the 

small, high-grade bodies that were mined. 

INTRODUCTION 

In recent years, world manganese production has 

increasingly come from large sedimentary deposits of 

shallow-marine origin. Stratigraphic units containing valuable manganese concentrations consist of carbonates or fine 

clastics and represent deposition during high sea level 

stands, particularly on the margins of stratified (black shale) 

basins (reviewed by Force and Cannon, 1988). Some of 

these shallow-marine manganese concentrations are quite 

inconspicuous. 

Virginia is not known to have shallow-marine manganese deposits, but supergene manganese deposits (i.e., 

manganese concentrations in weathered rock) are present 

over carbonate units of Early Cambrian, Late Cambrian to 

Early Ordovician, and Middle Devonian ages. The deposits 

Manuscript approved for publication November 2, 1989 

over lower Paleozoic rocks that are discussed in this paper 

have had the greatest production. None of the supergene 

deposits are presently mined. 

The distribution of supergene manganese concentrations may be a clue to the distribution of manganese in 

underlying parent rocks. The two lower Paleozoic rock 

assemblages now represented by supergene manganese 

deposits in Virginia seem broadly permissive of manganese 

concentration. They represent deposition in shallow-marine 

(and slope; Pfeil and Read, 1980) environments. Whether 

deposition was on the margins of stratified basins is not 

known in Virginia, but stratified-basin deposits of these 

ages are known elsewhere (Leggett, 1980; Goodfellow, 

1987). The carbonate (mostly dolomitic) units suggest high 

sea level stands and resulting absence of coarse-clastic 

dilution, in comparison to adjacent units. Thus the combination of permissive environment and supergene manganese 

deposits suggests that the manganese contents of these units 

should be established. Such a reconnaissance investigation 

is the purpose of this article. 

SUPERGENE DEPOSITS 

As recently as World War II, Virginia produced a 

large share of domestically mined manganese. This manganese came from supergene deposits, mostly over the Lower 

Cambrian Shady (Tomstown) Dolomite and adjacent rocks 

(fig. 1). Some production was from supergene deposits over 

Cambrian-Ordovician Knox Group dolomites and over 

Devonian rocks. The deposits over Devonian rocks are 

described separately. 

The supergene deposits over lower Paleozoic rocks 

. are described in a voluminous literature from the era of 

active mining. Hewitt (1916), Hewitt and others (1918), 

Stose and others (1919), Stose (1942), King (1943, 1950), 

Knechtel (1943), Stead and Stose (1943), and Miller (1944) 

Manganese Contents of Some Lower Paleozoic Carbonate Rocks of Virginia A 1 
0 

INDEX MAP OF VIRGINIA 

50 100 MILES I I I I I 

0 

I I 

I I I 

50 

I 

I 

100 KILOMETERS 

Figure 1. Index map showing locations of areas of sample collection, former manganese mining districts, and the outcrop 

belt of Shady Dolomite. Line is approximate belt of Shady Dolomite, dashed in interval lacking outcrop of lower Shady. 

The Knox Group, too complex to be shown at this scale, is approximately parallel to and northwest of the Shady. 

Sites of sample collection along measured sections: 

Shady Dolomite 

1, Harpers Ferry area 

2, Shenandoah River 

3, Austinville area 

4, Marion area 

Knox Group 

5, New River 

6, Tazewell area 

Other sites of sample collection: 

Shady Dolomite 

D, Dargan (Md.) 

B, Buchanan 

are some of the more important descriptions of deposits 

associated with Shady Dolomite; Stose and others (1919) is 

the most comprehensive. Stose and Miser (1922) describe 

the deposits on the Knox Group. 

Manganese oxide minerals described from these 

deposits include pyrolusite, "psilomelane," manganite, and 

"wad." Sixteen analyses of concentrates listed for deposits 

associated with Shady Dolomite, apparently representative 

of the major producers, average 39.9 percent manganese 

and 7.8 percent iron. For the seven analyses that list 

alumina, the average is 3.0 percent. The one analysis of a 

concentrate from a deposit over the Knox Group is similar. 

Knox Group 

R, Round Hill 

Former mining districts 

Shady Dolomite 

D, Dargan (Md.) 

E, Elkton 

C, Crimora 

L, Lyndhurst-Vesuvius 

3, Lick Mountain 

4, Glade Mountain 

Knox Group 

N, Newport 

6, Tazewell 

The ores, up to tens of meters thick, are of several 

types, including (in probable order of importance) (1) 

concretions and impregnations (locally forming ledges) of 

manganese oxides in saprolitic clay, (2) solution-collapse or 

other breccias with manganese-oxide cement, and (3) 

manganese-oxide detritus in colluvium. All the types are 

thus heterogeneous material, consisting of high-grade hard 

minerals in a voluminous barren host that may or may not 

be soft. Bulk manganese grades are therefore low, except 

for small tonnages of material. 

Theories that have been put forward to explain 

manganese enrichment in these deposits include: 

A2 Manganese Contents of Some Sedimentary Rocks of Paleozoic Age in Virginia 
1. Manganese, present as a minor constituent of underlying 

carbonate precursors, was residually concentrated in 

place as insoluble residue by dissolution during weathering (Stose and others, 1919; King and others, 1944; 

Stose, 1942; Knechtel, 1943; Miller, 1944; Stose and 

Stose, 1957). 

2. Manganese, from either underlying or adjacent formations, became fixed in the high-pH environment of 

weathering carbonate rock (Hack, 1965). Manganese 

may have been transported in regional ground waters to 

the carbonate trap from formations weathering upslope. 

3. Manganese may have been transported from depth to a 

surficial environment of precipitation via local plumbing 

systems, especially faults (Stead and Stose, 1943; Cooper, 1944). 

All these mechanisms appear plausible, and each 

seems capable of assuming a major share of supply in 

certain local conditions but seems not to work in others. The 

trapping of manganese dissolved in ground water is likely 

where carbonate hosts intercept a ground-water gradient. 

Hack (1965) has shown that where this condition is not met, 

few deposits occur in the Shady outcrop belt. That is, 

deposits associated with the Shady most commonly lie low 

on slopes whose upper reaches are composed of older 

noncarbonate units. However, in the Knox belt several 

deposits occupy hilltops and cannot presently be supplied 

with manganese in this way. Several deposits in the Knox 

belt appear to be closely associated with faults (Stose and 

Miser, 1922; Cooper, 1944); in these deposits fluids in 

permeable gouge zones probably precipitated manganese 

oxides near the land surface. 

Although in-place enrichment of manganese in the 

insoluble residue of carbonate parent rocks is the most 

popular hypothesis, almost nothing is known of the manganese content of the parent rocks. King and others ( 1944) 

and Rodgers (1945) present a few analyses of Shady 

Dolomite from Tennessee showing over 1 percent manganese, which has given some comfort to proponents of this 

hypothesis. Until recently, there was no reason to believe 

that the manganese content of these carbonate parent rocks 

could itself be of economic interest. 

"PARENTAL" CARBONATE BEDROCK 

Shady (Tomstown) Dolomite and underlying 

quartzite 

The Shady Dolomite is of Early Cambrian age and is 

the basal carbonate unit of the Paleozoic sequence across 

the entire State. The unit is as much as 1,800 ft (550 m) 

thick. The upper portion of the unit consists mostly of 

massive thick-bedded dolomite with some chert, whereas 

the basal portion, called the Patterson Member in the 

southwestern part of the State, is finely banded and contains 

limestone lenses and beds. The Shady overlies quartzites 

known as Antietam to the north of Roanoke and Erwin to 

the south. A transitional interval up to about 10 m thick is 

present in some areas, especially toward the southwest. The 

Patterson Member and the transitional interval are of 

particular interest in this report because they are spatially 

associated with the supergene manganese enrichments. 

Exposure of the Shady Dolomite is generally poor 

except along river gorges and associated man-made cuts. 

Indeed, for a considerable portion of its outcrop length, 

between about Front Royal and Buena Vista, only a few 

exposures are known. Some of the most valuable districts of 

supergene manganese deposits (Elkton, Crimora, and 

Vesuvius-Lyndhurst) occur in this interval, and for these 

deposits the parent-rock material is not known. Thick 

residual clay occupies the position of Shady Dolomite in 

this geographic interval. 

The depositional setting of the Shady Dolomite is 

predominantly a shallow-marine shelf. Pfeil and Reid 

(1980) took advantage of structural repetition of the unit in 

the Austinville area to conduct an areal facies study, which 

showed the presence of deeper-water slope facies toward 

the southeast. 

The transitional zone between the basal Patterson 

Member of Shady Dolomite and the Antietam-Erwin 

Quartzite is best known in the southeastern part of the State 

and in the adjacent Shady Valley of Tennessee (the type 

atea of the Shady Dolomite). The transitional zone has been 

described in Virginia by Stose (1942), Miller (1944), and 

Stose and Stose (1957), who report phosphatic and/or · 

glauconitic, ferruginous to calcareous, fossiliferous sandstones in this interval. These authors hypothesize that the 

rocks of the transitional zone are an important source of 

manganese for supergene deposits; however, the high manganese contents reported from the Shady in adjacent Tennessee (King and others, 1944; Rodgers, 1945) are from a 

slightly higher stratigraphic interval. 

The Antietam-Erwin Quartzite directly underlies 

some manganese deposits, and in some districts, such as the 

Glade and Lick Mountain districts (Stead and Stose, 1943; 

Miller, 1944), a considerable share of manganese resources 

occurs over this quartzite. Typically, manganese oxides in 

such districts occur as a matrix in brecciated quartzite. 

Knox Group 

The Knox Group, which spans the CambrianOrdovician boundary, consists largely of dolomite, with 

some limestone units and with replacement chert throughout. The lower Ordovician part of the unit in the northern 

part of the State is known as the Beekmantown Dolomite. 

Supergene deposits of manganese (Stose and Miser, 

1922), occur over rocks of the Knox Group in Giles County 

and in the southwestern part of the State (fig. 1). They occur 

Manganese Contents of Some lower Paleozoic Carbonate Rocks of Virginia A3 
over rocks that may be at different stratigraphic levels, and 

it seems possible that structural control is more important 

than stratigraphic control in these deposits. Near Tazewell 

in the southwestern part of the State, supergene manganese 

deposits seem most closely associated with the Upper 

Cambrian part of the Knox Group, known as the Copper 

Ridge Dolomite (Cooper, 1944). 

STUDY METHODS 

Sections that are fairly complete and stratigraphically 

intact, located as near as possible to important districts of 

derived supergene manganese deposits, were collected. It 

was also thought desirable to collect within the same thrust 

sheet as the supergene deposits. 

Because of a scarcity of adequate sections, only four 

areas of lower Shady and two of the lower Knox were 

collected as sections (fig. 1). Other collections from inadequately exposed or structurally complex sections are also 

shown on figure 1. The long geographic interval with 

inadequate exposure of Shady Dolomite, extending virtually from the Shenandoah River section near Front Royal to 

the James River sections near Buchanan, is a major limitation to this study. 

Analyzed samples are all of fresh rock, trimmed of 

contaminated surfaces. Samples were taken at regular 

intervals of about 1-10m; the interval was adjusted where 

necessary to include lithologic variants. Where possible, 

composite chip samples, representative of as much as 20m 

in thickness within a relatively uniform lithologic interval, 

were collected for analysis. This method, which provides 

average values, is useful for defining anomalous intervals 

where background values are sufficiently low. In this study, 

where background manganese values were on the order of 

100 parts per million (ppm), a bed containing 5 percent 

manganese over a thickness of only 1 m would be represented in the bulk analysis of a 20-m interval by manganese 

values 25 times background. 

Two types of analyses were used for each sample. 

First, 30-element semiquantitative spectrographic analysis 

or 64-element emission spectrographic analysis served to 

determine whether unusual patterns of elemental concentration were present. Second, all samples were reanalyzed for 

manganese and the related elements iron, phosphorus, and 

barium by inductively coupled plasma (ICP) spectroscopy. 

The latter values are those tabulated for these four elements; 

the ICP analyses for manganese show slightly lower values 

than do the other two methods, but the manganese values 

obtained with different analytical methods plot against each 

other as straight lines with little scatter. 

Analyses by spectrographic methods were by B. 

Arbogast and C. Skeen of the U.S. Geological Survey in 

Reston, and ICP analyses were by W. d' Angelo, of the 

U.S. Geological Survey in Reston. 

Table 1. Manganese and other elemental contents of the 

Harpers Ferry section 

[Mn = manganese, Fe = iron, and Ba = barium.) 

Stratigraphic position Mn Fe 

(ppm) (%) 

Antietam Quartzite 

A. Uppermost exposed 310 2. 8 

in rail cut 

B. 9.1 m below A 110 3.1 

- Outcrop gap -

Shady Dolomite 

A. Lowermost exposed 240 0.8 

in rail cut 

B. 3.1 m above A 170 0.4 

C. 7.8-8.5 m above A 110 0.1 

D. 11.5 m above A 83 0.3 

-John Brown's cave 12.4-15.3 mE. 14.5 m above A 95 0.4 

F. 16.3-17.1 m above A 58 0.2 

G. 22.0-22.2 m above A 120 0.6 

H. 45 m above A 37 0.1 

Anomalies of 

other elements 1 

1,100 ppm of Ba 

1,200 ppm of Ba 

1

Defined as concentrations relative to other samples of the same 

lithology, especially those of this study. 

MANGANESE CONTENTS 

Analytical results are summarized by area, from 

northeast to southwest in each unit (fig. 1). 

Shady Dolomite and underlying quartzite 

Harpers Ferry area 

The Antietam Quartzite-Shady Dolomite transition 

was examined in the Harpers Ferry area of West Virginia 

and Maryland, about 3 km north of Virginia, because these 

rocks are well exposed there. A supergene deposit of 

manganese oxides over Shady Dolomite was mined at 

Dargan, Md., about 2 km north. 

A measured section was collected along the Baltimore and Ohio Railroad cuts north of the town of Harpers 

Ferry on the Potomac River (Charles Town quadrangle). 

The collection is discontinuous because of a gap in fresh 

rock outcrop that includes the Antietam-Shady contact. This 

gap appears to include over 100 m of stratigraphic section. 

Two samples were collected below and eight above this gap 

(in Antietam and Shady, respectively). The portion of 

Shady sampled consists toward the base of laminated 

limestone and toward the top of limestone with small 

replacement "eyes" of dolomite. Table 1lists the results; the 

location of John Brown's Cave is shown to aid relocation. 

The highest manganese content analyzed, 240 ppm, 

is from the lowest beds of the Shady Dolomite exposed in 

the rail cut. This lithology is a finely laminated limestone, 

and appears (from observations of float) to be about 30m 

A4 Manganese Contents of Some Sedimentary Rocks of Paleozoic Age in Virginia 
Table 2. Manganese and other elemental contents of the 

Shenandoah River section 

[Mn = manganese, Fe = iron, Sr = strontium, and Ba = barium.] 

Meters above basal outcrop 

Mn Fe Anomalies of 

(ppm) (%) other elements 

0-1.0 91 0.1 3,000 ppm of Sr 

4.5-5.0 77 0.1 

- Outcrop gap -

18.0-19.0 28 0.1 

19.0-20.0 66 0.1 

24.0-25.0 32 <0.1 

- Outcrop gap 29.0-37.5 -

39.2-39.6 120 0.1 

42.5-43.5 38 0.1 

50.5-51.5 46 0.1 

58.5-59.5 55 0.2 

64.8-65.3 62 0.2 

70.3 77 0.1 1,600 ppm of Ba 

above the base of the formation. Manganese values 

decrease upward in the unit, except in the 22.0 to 22.2-m 

sample, which is siliceous. 

Three samples of Shady Dolomite were also collected 

at the Dargan mine, to investigate the possibility that strong 

lateral gradients in manganese composition controlled the 

location of supergene deposits. These three samples contained 200 to 500 ppm manganese by spectrographic analysis (which everywhere gave higher values than ICP). 

Shenandoah River section 

The Shenandoah River exposes a section of Shady 

Dolomite, on the south bank, on the northern side of 

Calmes Neck (Ashby Gap quadrangle). No quartzite was 

seen in place, but the section measured by William F. 

Cannon and the author begins at the base of Shady Dolomite 

as depicted by Gathright and Nystrom (1974). This section 

is about 35 km southwest of the Harpers Ferry section. The 

nearest supergene manganese prospects, outside Front 

Royal about 20 km further southwest, are very lean. Table 

2 shows the manganese contents of this section of Shady 

Dolomite. The entire measured interval consists of welllaminated to poorly laminated limestone with blebs and 

nodules of dolomite. The specimen at 39.2 to 39.6 m, 

which is the most dolomitic, contains the most manganese, 

120 ppm. 

Buchanan area 

The Shady Dolomite is well exposed in the Buchanan 

area along the James River and in Norfolk and Western 

railroad cuts parallel to it. However, it appears that faulting 

has cut out the basal limestone unit of the Shady. Eight 

specimens were collected in a dolomite quarry operated by 

James River Limestone, Inc. ("plant 1 "), about 2.5 km 

east-northeast of the town of Buchanan (Buchanan quadrangle). In this quarry, the structurally lower portion of the 

Shady is coarsely recrystallized, massive, and veined and is 

in apparent fault contact with Unicoi(?) sandstone beds that 

are truncated by the fault. Six specimens of Shady in this 

area of the quarry, aggregated into three samples for 

spectrographic analysis, ranged from 500 to 1,000 ppm of 

manganese. The one nearest the fault contained 100 ppm 

lead, also. In the area of the weighing station, northwest of 

the recrystallized, massive, veined dolomite, is a structural 

interval of thin-bedded dolomites with stromatolites and 

shale partings. A composite chip sample of these beds 

yielded 500 ppm of manganese. At the northwest end of the 

quarry are dark dolomites from which a chip sample shows 

200 ppm of manganese. 

Four specimens were also collected along rail cuts to 

the northeast about 3 km, between the bridge of County 

Road 614 and Jennings Creek. This section is also structurally complex, and the Shady is entirely dolomitic except 

in a few thin intervals. These specimens, aggregated into 

two samples for spectrographic analysis, contain 500 to 700 

ppm of manganese. One additional specimen of Shady was 

collected from a roadcut along nearby Bearwallow Creek, 

where manganese oxide forms small supergene enrichments 

as the cement of quartzite-clast breccia. This specimen of 

Shady contained 500 ppm of manganese. 

Austinville-Ivanhoe area 

Shady Dolomite is well exposed in this district, where 

it hosts historically important deposits of lead and zinc. 

Supergene manganese deposits are present in the district on 

Lick Mountain. The basal portions of the Shady were 

measured west of Fosters Falls on the east bank of the New 

River, in Norfolk and Western railroad cuts (Fosters Falls 

quadrangle). The quartzite contact is not well exposed in the 

rail cuts, but its position can be surmised within 10m. The 

dominant lithology throughout the sampled interval is 

laminated carbonate, with varying ratios of calcite and 

dolomite, which is present as nodular clusters. Dolomitic 

sedimentary breccia is also present in the 13- to 18-m 

interval containing the highest manganese values (table 3). 

The three samples from 5 to 56 m above the base of 

the Shady gave the highest manganese values of this study, 

but manganese contents are nevertheless well under 1 

percent. Lead and zinc values in this interval are also high. 

Iron content is approximately proportional to manganese 

content. 

A subsidiary collection was made on a road cut of 

State Highway 54 on the north bank of the New River 

beside Galena Creek (Max Meadows quadrangle). In part of 

this exposure, dolomitic collapse breccia cuts the contact of 

quartzite and overlying Shady. The intact part of the 

exposure, toward the east, provides details of the contact 

not available at Fosters Falls. Table 3 shows the manganese 

Manganese Contents of Some Lower Paleozoic Carbonate Rocks of Virginia AS 
Table 3. Manganese and other elemental contents of the 

Fosters Falls and Galena Creek sections 

[Mn = manganese, Fe = iron, Zn zinc, Pb = lead, and P = 

phosphorus.] 

Meters above base of Mn Fe Anomalies of 

Shady Dolomite1 (ppm) (%) other elements 

Fosters Falls Section 

- Outcrop gap -

5-6 (approximate) 1,500 1.1 

- Outcrop gap -

13-18 3,000 2.5 850 ppm of Zn and 

82 ppm of Pb 

- Outcrop gap -

35-56 2,500 1.8 290 ppm of Zn and 

120 ppm of Pb 

- Outcrop gap -

65-85 450 0.3 

85-103 250 0.2 

Galena Creek Section 

Stratigraphic relation to contact zone 

3-7m below 620 3.6 0.09% P 

0-3 m below 500 3.4 

1.8-m contact zone 1,300 2.5 

0-3 m above 1,100 1.4 

1

Measurements are corrected for dip. 

contents of these rocks. Within the 10 m of section, 

chloritic to glauconitic quartzite passes upward through 

glauconitic granular sand interbedded with dolomite and 

laminated shale, into massive dolomite, apparently bioturbated. Neither manganese nor lead-zinc contents are as high 

as at Fosters Falls. Manganese shows a maximum in the 

transition beds. Some phosphate apparently accompanies 

glauconite. 

Marion area 

The Glade Mountain district of supergene manganese 

deposits, south of Marion, was the most recent significant 

producer of manganese in the State. I was not able to find 

an adequate section of the Antietam-Erwin Quartzite and 

the lower Shady on Brushy Mountain, where the largest 

deposits occur, but had to content myself with a short 

section across the Shady contact in the Rye Valley, to the 

Table 4. Manganese and other elemental contents of the 

Sugar Grove section 

[Mn = manganese, Fe = iron, Ba =barium, and P = phosphorus.] 

Stratigraphic relation Mn Fe Anomalies of 

to contact zone (ppm) (%) other elements 

0-3 m below 810 2.6 1 ,400 ppm of Ba 

1-m contact zone 930 2.2 0.09% p 

0-3 m above 960 1.3 

3-6m above 700 1.0 

south. This section is near Sugar Grove, in the banks of 

Dickey Creek, along County Road 16, near Saltpeter Cave 

(Atkins quadrangle). The exposed transition is from fine 

laminated quartzite, through glauconitic quartzite and dolomites, to whitish dolomite with calcareous lenses. Manganese contents, shown in table 4, show a very slight 

maximum, below 0.1 percent, just above the contact. 

Summary 

Analyses of four stratigraphic sections across the 

Shady Dolomite and underlying quartzite suggest that 

manganese contents reach a maximum in the lowermost 

Shady throughout Virginia. This corresponds to the stratigraphic interval on which supergene enrichments occur and 

supports the hypothesis that the manganese enrichments 

derive from the rocks on which they rest. However, none of 

the sedimentary rocks analyzed from this interval show 

manganese contents of even 1 percent. Thus these rocks 

themselves are of no economic interest. 

The average manganese content of the 24 samples 

analyzed by ICP from the Shady and underlying quartzite is 

490 ppm. The average content differs little between Shady 

and quartzite samples. Manganese content is roughly proportional to iron content in samples of Shady Dolomite (fig. 

2) both within individual sections and as an entire array. 

The highest manganese/iron ratios are about 0.15, suggesting that fractionation of iron and manganese, necessary to 

form valuable manganese concentrations, was not occurring 

in this sedimentary environment. 

The degree of manganese enrichment required to 

form a typical supergene concentration from average parent 

rocks is about 800 times in this area. To contend that all this 

enrichment has resulted only from weathering strains one's 

credibility. Other insoluble elements normally enriched in 

weathering profiles, for example, iron and aluminum, have 

not been enriched to the same degree. Iron in the analyzed 

parent carbonate rocks ranges from 0. 04 percent to 2. 5 

percent, and averages 0.6 percent. Alumina (from semiquantitative spectrographic analyses) ranges from 0.6 percent to 6.2 percent, and averages 2.2 percent. The enrichment required to make a supergene concentration of typical 

composition from average Shady is only about 13 times for 

iron and 1.4 times for aluminum. This reasoning suggests 

that enrichment of manganese in supergene deposits extends 

beyond simple residual enrichment. 

Further enrichment may have taken two forms: 

1. Preferential enrichment of manganese by geochemical 

trapping in the supergene environment. This hypothesis 

is essentially that proposed by Hack ( 1965). Manganese 

carried in solution by ground water from a variety of 

sources (including immediately underlying rocks) would 

preferentially be precipitated in supergene deposits over 

rocks that alter the geochemical environment of the 

ground water. 

A6 Manganese Contents of Some Sedimentary Rocks of Paleozoic Age in Virginia 
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2.5 D 

2.4 

2.3 

2.2 

2.1 

2.0 

1.9 

1.8 D 

1.7 

1.6 

1.5 

1.4 D 

1.3 'V 

1.2 

1.1 D 

1.0 

.9 

.8 0 

. 7 

SAMPLE LOCATIONS 

.5 0 Harpers Ferry 

.4 1:::. Shenandoah River 

.3 D D Fosters Falls-Galena Creek 

v Sugar Grove 

.2 D 

0

o 200 400 600 800 1000 1200 1400 1600 1800 2000 2200 2400 2600 2800 3000 

MANGANESE (PARTS PER MILLION) 

Figure 2. Manganese and iron contents (by inductively 

coupled plasma analysis) of samples of Shady Dolomite. 

2. Enrichment of manganese relative to other elements, 

especially aluminum, as concretions and small orebodies 

within the supergene deposit. Exposures of some of 

these deposits certainly suggest local enrichment, as the 

distribution of manganese is extremely inhomogeneous, 

and the tonnage of manganese ore is a small percentage 

of the tonnage of residual material. That is, some 

enrichment occurred in the formation of the weathered 

overburden as a whole, and further enrichment occurred 

to form ore-grade bodies. 

Knox Group 

The largest supergene manganese deposits over rocks 

of the Knox Group are in the southwestern part of the State 

Table 5. Manganese and other elemental contents of the 

New River section, Knox Group 

[Mn =manganese, Fe= iron, Cr =chromium, Ni =nickel, Pb =lead, 

Cu = copper, and Mo = molybdenum.] 

Meters above Mn Fe Anomalies of base of 

Knox Group1 (ppm) (%) other elements 

10 86 

26 110 0.1 

110 88 

235 100 0.5 200 ppm of Cr, 70 ppm of Pb, 

50 ppm of Ni and Cu, and 

10 ppm ofMo 

365--470 88 0.5 

496 43 

550 86 

600 85 

1

The Knox Group is 650-m thick here. 

(fig. 1). Sampling was therefore concentrated in that region, 

except for a reconnaissance investigation at the northernmost known prospect . 

Round Hill 

The Scott prospect is atop Round Hill, near Strasburg 

between Interstate Highway 81 and U.S. Highway 11 

(Toms Brook quadrangle). Manganese concretions at the 

Scott prospect are iron-rich and cherty and, therefore, not of 

economic interest. Underlying Beekmantown Dolomite is 

not well exposed. Two short chip samples collected on 

County Road 651 for spectrographic analysis contained 100 

and 500 ppm of manganese. No other elemental concentrations were of interest. 

New River section 

Several supergene manganese deposits in the Newport area of Giles County are on dolomite of the Knox 

Group, and the nearby New River section was, therefore, 

sampled to establish the composition of the dolomite. 

Sampling was conducted along the Norfolk and Western 

railroad cuts south of Goodwins Ferry (Eggleston quadrangle). Sampling was keyed to an unpublished section measured by A.T. Ovenshine, incorporated in table 5. Lithologies are mostly dolomitic, with a few limestone horizons 

up to about 10-m thick (one at 496 m). Laminated, 

bioturbated, and oolitic horizons are present. Chert nodules 

are present in many beds. The specimen at 235m, with high 

base metal contents, is a dark, shaly dolomite. Manganese 

contents of all the analyzed rocks are low. 

Tazewell area 

A section at Wittens Mills (Tiptop quadrangle) was 

sampled (table 6) in order to assess the composition of the 

Manganese Contents of Some lower Paleozoic Carbonate Rocks of Virginia A7 
Table 6. Manganese and other elemental contents of the 

Wittens Mills section, Knox Group 

[Mn = manganese, Fe = iron, Zn = zinc, and Pb = lead.] 

Meters above Mn Fe Anomalies of base of (ppm) (%) other elements Copper Ridge Dolomite 

40-49.8 160 0.1 

- Outcrop gap -

52.4-60.5 130 0.1 

60.5-65.7 200 0.2 

65.7-83.7 130 0.2 410 ppm of Zn and 

95 ppm of Pb 

83.7-108.8 190 0.2 

- Outcrop gap -

143.4-154.7 180 0.2 

154.7-168.1 170 0.3 

168.1-185.8 150 0.3 

185.8-187.2 140 0.5 

Copper Ridge Dolomite, locally the basal formation of the 

Knox Group. These rocks apparently underlie supergene 

manganese enrichments 3-4 km northeast. The section was 

composite, measured partly along County Road 651 and 

partly along the Norfolk and Western railroad cuts. An 

outcrop gap represents about 100m of section. All the beds 

are dolomitic, and most are either laminated micrites or 

massive arenites that are locally oolitic. Shaly layers, 

shellbeds, and intraformational conglomerates are present. 

The 65.7- to 83.7-m interval with high lead and zinc content 

consists of two lithologies, one of fine dolomites with algal 

laminae and the other of oolites replaced by chert. 

Summary 

The analyzed rocks of the Knox Group contain an 

average of 125 ppm manganese, probably too little to 

explain the supergene manganese deposits on them by 

simple residual enrichment. The supergene manganese 

enrichments on the Knox typically occur as cement of 

chert-fragment breccia, and are closely associated with the 

surface traces of the Saltville and related faults. These facts 

suggest that a fault-related plumbing system is more important in manganese supply than is the composition of 

carbonate rocks in forming supergene deposits on the Knox. 

Indeed, even rather fresh specimens of fault breccia along 

the Saltville fault contain manganese in the vicinity of 

Newport (Art Schultz, U.S. Geological Survey, oral commun., 1987). Precipitation reactions controlled by carbonate rocks may have determined the locus of manganese 

deposition both at depth and at the surface. 

CONCLUSIONS 

The manganese contents of lower Paleozoic carbonate rocks of Virginia are too low to explain the supergene 

manganese deposits developed on them solely as residual 

enrichments. The manganese contents of the carbonate 

rocks are typically about 100-500 ppm, and high values 

range up only to 3,000 ppm, or 0.3 percent. In the deposits 

over Shady Dolomite and underlying quartzite, it is likely 

that manganese has been trapped in overburden by the 

increased alkalinity of ground water over the carbonate 

rocks. In the deposits over the Knox Group, it is likely that 

ground water moving along faults has brought manganese 

into the overburden. In both cases, further concentration 

within the overburden geochemical system has resulted in 

the small, high-grade bodies that were mined. 

REFERENCES CITED 

Cooper, B.N., 1944, Geology and mineral resources of the Burkes 

Garden quadrangle, Virginia: Virginia Geological Survey 

Bulletin 60, 299 p. 

Force, E.R., and Cannon, W.F., 1988, Depositional model for 

shallow-marine manganese deposits around black shale 

basins: Economic Geology, v. 83, p. 93-117. 

Gathright, T.M., and Nystrom, P.G., 1974, Geology ofthe Ashby 

Gap quadrangle, Virginia: Virginia Division of Mineral 

Resources Report Investigation 36, 55 p. 

Goodfellow, W.O., 1987, Anoxic stratified oceans as a source of 

sulfur in sediment-hosted stratiform Zn-Pb deposits 

(Selwyn Basin, Yukon, Canada): Chemical Geology, v. 65, 

p. 359-382. 

Hack, J.T., 1965, Geomorphology of the Shenandoah Valley, 

Virginia and West Virginia, and origin of the residual ore 

deposits: U.S. Geological Survey Professional Paper 484, 

84 p. 

Hewitt, D.F., 1916, Some manganese mines in Virginia and 

Maryland: U.S. Geological Survey Bulletin 640-C, p. 

37-71. 

Hewitt, D.F., Stose, G.W., Katz, F.J., and Miser, H.D., 1918, 

Possibilities for manganese ore on certain undeveloped tracts 

in Shenandoah Valley, Virginia: U.S. Geological Survey 

Bulletin 660-J, p. 271-296. 

King, P.B., 1943, Manganese deposits of the Elkton area, 

Virginia: U.S. Geological Survey Bulletin 940-B, p. 15-55. 

--1950, Geology of the Elkton area, Virginia: U.S. Geological Survey Professional Paper 230, 82 p. 

King, P.B., Ferguson, H.W., Craig, T.C., and Rodgers, John, 

1944, Geology and manganese deposits of northeastern 

Tennessee: Tennessee Division of Geology Bulletin 52, 

275 p. 

Knechtel, M.M., 1943, Manganese deposits of the LyndhurstVesuvius district, Augusta and Rockbridge counties, Virginia: U.S. Geological Survey Bulletin 940-F, p. 163-198. 

Leggett, J.K., 1980, British Lower Paleozoic black shales and 

their paleooceanographic significance: Journal Geological 

Society London, v. 137, p. 129-156. 

Miller, R.L., 1944, Geology and manganese deposits of the Glade 

Mountain district, Virginia: Virginia Geological Survey Bulletin 61, 150 p. 

Pfeil, F.W., and Read, J.F., 1980, Cambrian carbonate platform 

marginal facies, Shady Dolomite, southwestern Virginia, 

U.S.A.: Journal of Sedimentary Petrology, v. 50, p. 91-116. 

A8 Manganese Contents of Some Sedimentary Rocks of Paleozoic Age in Virginia 
Rodgers, John, 1945, Manganese content of the Shady Dolomite 

in Bumpass Cove, Tennessee: Economic Geology, v. 40, 

p. 129-135. 

Stead, F.W., and Stose, G.W., 1943, Manganese and quartzite 

deposits in the Lick Mountain district, Wythe County, 

Virginia: Virginia Geological Survey Bulletin 59, 16 p. 

Stose, A.J., and Stose, G.W., 1957, Geology and mineral 

resources of the Gossan Lead district and adjacent areas in 

Virginia: Virginia Division Mineral Resources Bulletin 72, 

233 p. 

Stose, G.W., 1942, Source beds of manganese ore in the Appalachian Valley: Economic Geology, v. 3 7, p. 163-172. 

Stose, G.W., and Miser, H.D., 1922, Manganese deposits of 

western Virginia: Virginia Geological Survey Bulletin 23, 

206 p. 

Stose, G.W., Miser, H.D., Katz, F.J., and Hewitt, D.J., 1919, 

Manganese deposits of the west foot of the Blue Ridge, 

Virginia: Virginia Geological Survey Bulletin 17, 166 p. 

Manganese Contents of Some Lower Paleozoic Carbonate Rocks of Virginia A9 

Chapter B 

Manganese Contents of Some Rocks of 

Silurian and Devonian Ages in Northwest 

Virginia 

By LESLIE J. COX 

A presentation of geochemical data 

from measured sections of sedimentary rocks 

of Silurian and Devonian ages 

that underlie supergene manganese deposits 

in northwest Virginia 

U.S. GEOLOGICAL SURVEY BULLETIN 1916 

MANGANESE CONTENTS OF SOME SEDIMENTARY ROCKS OF PALEOZOIC AGE 

IN VIRGINIA 

CONTENTS 

Abstract Bl 

Introduction Bl 

Mining in the Study Area Bl 

Depositional Setting of the Helderberg Group and Ridgeley Sandstone B2 

Theories on the Origins of Supergene Manganese Concentrations over Rocks of 

Devonian Age in Virginia B4 

Methods of Study BS 

Field Methods BS 

Analytical Methods B6 

Petrographic Methods B6 

Results of Chemical Analyses BS 

Manganese Contents at Each Section (North to South) BS 

Manganese Contents by Lithology BS 

Manganese Contents in the Rocks of the Liberty Furnace Section BlO 

Field and Chemical Observations BlO 

Petrographic Observations B14 

Discussion BlS 

Hypothesis of Manganese Enrichment BlS 

References Cited BlS 

FIGURES 

1. Index of geologic maps of the study area B2 

2. Area of outcrop map showing the locations of Lower and Middle Devonian formations, manganese mines in Cedar Creek Valley, prospects near Liberty Furnace, 

and the sections sampled in northwest Virginia B3 

3. Regional chronostratigraphic correlation chart showing rocks of Cayugan and Ulsterian age in the central Appalachian basin B4 

4. Restored stratigraphic section showing locations of studied sections and cathodoluminescent zonations B6 

5. Chronostratigraphic and lithostratigraphic sections of Paleozoic rocks in Virginia at 

Liberty Furnace, Fulks Run, Richards Run, Paddy Run, and Baldwin Gap, showing the manganese contents of the intervals sampled B7 

6. Area of outcrop map showing the location of the Ridgeley Sandstone and New 

Scotland Limestone formations near Liberty Furnace, Va. BlS 

TABLE 

1. Results of analyses of rock samples B12 

Contents Ill 

CHAPTER B 

Manganese Contents of Some Rocks of Silurian and 

Devonian Ages in Northwest Virginia 

By Leslie J. Cox 

Abstract 

The lower Paleozoic carbonate formations that form 

the substrate of supergene manganese deposits in Virginia 

have an apparent potential for manganese resources in 

shallow-marine sedimentary deposits. Those formations 

of Silurian and Devonian ages that form the substrate of 

supergene manganese deposits in northwest Virginia 

were analyzed for manganese and other elements in this 

reconnaissance investigation. The rocks were found to 

generally contain only 100 to 400 parts per million (ppm) of 

manganese. However, manganese contents as high as 0.15 

percent were found in the silicified and fractured limestone beds of the upper Helderberg Group near Liberty 

Furnace, Va. The higher concentrations of manganese in 

these altered rocks are attributed to incipient, in-place 

weathering of rocks that may have had manganese-rich 

carbonate cement prior to local destruction of original 

fabrics. 

Upper Helderberg Group limestones contain zones 

of manganese-rich carbonate cements fixed in geographic 

distribution by the distances meteoric ground waters 

traveled from recharge areas exposed in Devonian time 

(Dorobek, 1987). There may be a correlation between the 

location of residually concentrated manganese in the 

study area and the paleo-zone traversed by reduced 

meteoric ground waters. 

INTRODUCTION 

The manganese resources in Virginia consist of 

supergene concentrations of manganese oxides, which lie 

above folded sedimentary rocks of Paleozoic age in the 

Valley and Ridge Province of the Central Appalachian 

Mountains. The supergene deposits of Virginia were an 

important source of domestically produced manganese from 

Manuscript approved for publication November 2, 1989. 

before the Civil War (as early as the mid 1830's) until after 

World War II (as late as the late 1950's). The largest share 

of manganese came from the supergene deposits over 

carbonate rocks of Early Cambrian age. Lesser amounts 

were extracted from deposits over dolomites of CambrianOrdovician age and limestones of Middle Devonian age. 

Throughout the 1900's, exploration for manganese 

resources in Virginia was directed toward the discovery of 

additional supergene deposits. Although the favored 

hypothesis of origin for the supergene deposits was in-place 

enrichment of manganese in the insoluble residue of carbonate parent rocks, little was reported about the manganese contents of the parent rocks. 

The potential for significant primary (sedimentary) 

concentrations of manganese in Virginia remained unexplored until Force (this report, Chapter A) suggested that 

the lower Paleozoic carbonate formations beneath the supergene deposits were permissive for shallow-marine sedimentary manganese deposits. Guided by the hypothesis that the 

distribution of supergene manganese concentrations might 

reflect a similar distribution of inconspicuous yet significant 

manganese concentrations in the parent rocks, Force (this 

report, Chapter A) undertook a systematic reconnaissance 

exploration of the rocks of Cambrian and Ordovician age in 

Virginia in order to document their manganese contents. 

This study investigates the manganese contents of 

the Devonian hosts of the supergene manganese deposits in 

the vicinity of Cedar Creek Valley in northwest Virginia 

(fig. 1). 

Mining in the study area 

The supergene manganese deposits and occurrences 

lie over the tightly folded rocks of the Helderberg Group of 

Upper Silurian-Lower Devonian age and the Ridgeley 

Sandstone of Devonian age (fig. 2). The manganese ore 

Manganese Contents of Some Rocks of Silurian and Devonian Ages in Northwest Virginia 81 
Figure 1. Index of geologic maps of the study area. Map 

references are keyed by number: 1, Calver and Hobbs 

(1963), (scale 1:500,000 (clear area only); 2, Brent (1960), 

scale 1:62,500 (stippled area); 3, Butts and Edmundson 

(1966), scale 1:62,500 (stippled area); 4, Monroe (1942), 

scale 1:24,000 (shaded area); 5, Young and Rader (1974), 

scale 1:24,000 (ruled area); and 6, Rader and Biggs (1976), 

scale 1:24,000 (shaded area). 

minerals occur in the residuum of the uppermost limestone 

beds of the Helderberg Group and in the open spaces of 

fractured Ridgeley Sandstone, which lies above the limestones of the Helderberg Group. The residuum consists of 

variable amounts of yellow sandy clay, cherty clay, clay, 

and ore. 

The production of manganese oxide ore in Cedar 

Creek Valley began with the opening of the Mineral Ridge 

mine (fig. 2, locality a) in 1834; the Godlove, Bonnet Hill, 

and Capola Mountain mines (fig. 2, localities b,c, and d), 

were opened in 1847, 1848, and 1880, respectively (Stose 

and Miser, 1922). In the same era, manganese oxides were 

mined from the High Head prospects (fig. 2, locality e) in 

the Stony Creek drainage basin. These deposits were mined 

intermittently until the early 1920's; several were reopened 

in 1940 (McGill, 1936; Monroe, 1942). Production at the 

Mineral Ridge mine ceased in 1957 (Butts and Edmundson, 

1966). The ore was taken from depths as great as 200 ft 

(Stose and Miser, 1922), but more typically from depths 

less than 100 ft. None of these deposits are mined today. 

Detailed information on each mine and prospect in the 

Cedar Creek Valley manganese district is given by Stose 

and Miser (1922) and Monroe (1942). 

Depositional setting of the Helderberg Group 

and Ridgeley Sandstone 

In Silurian and Devonian time the Appalachian basin 

extended northeast through what is now Virginia-West 

Virginia-Maryland. Tectonic highlands of low relief bordered the eastern side of the central Appalachian foreland 

basin. A sequence of mixed siliciclastic-carbonate sediments, the Helderberg Group, were deposited on a gently 

sloping, carbonate ramp that was built westward from the 

tectonic highlands (Dorobek and Read, 1986). 

At the time of the last and uppermost transgressive 

sequence of Helderberg Group deposition, described by 

Dorobek and Read ( 1986), the deepest part of the basin lay 

northwest of the study area. There, the dark color and fossil 

content of the Mandata Shale indicate that the water was 

oxygen-depleted (Dorobek and Read, 1986). Limestones 

indicative of shallower, above-wave base, oxygenated 

water were deposited near the basin edge east and south of 

the study area. Between the deepest part of the basin and the 

shore, nodular-bedded, shaly, and cherty limestones were 

deposited below fair-weather wave base in the lessoxidizing conditions of the deep-ramp setting (Dorobek and 

Read, 1986). These limestones are known as the New 

Scotland Limestone (Young and Rader, 197 4) in the study 

area and as the Corriganville Limestone and Lower Licking 

Creek Formations (Dorobek and Read, 1986) south of the 

study area (fig. 3). The depositional setting described above 

for the Appalachian basin in the Middle Devonian (apparent 

oxygen stratification and carbonate deposition at a time of 

high sea level stand (transgression)) indicate that the deepramp sediments are broadly permissive for shallow-marine 

manganese deposits as modeled by Force and Cannon 

(1988). 

At the onset of the Acadian orogeny, Middle Devonian clastics and bioclastics (Ridgeley Sandstone, Huntersville Chert, and Needmore Shale) spread westward and 

buried the Helderberg Group. The New Scotland Limestone 

Figure 2. Outcrop map showing the locations ~ 

of Lower and Middle Devonian formations, manganese mines in Cedar Creek Valley, prospects near 

Liberty Furnace, and the sections sampled in northwest Virginia. 

82 Manganese Contents of Some Sedimentary Rocks of Paleozoic Age in Virginia 
EXPLANATION l/1 I I Outcrops of the Ridgeley Sandstone and the 

New Scotland Limestone, undivided 

'X' Manganese mine 

a. Mineral Ridge mine 

b. Godlove mine 

c. Bonnet Hill mine 

d. Capola Mountain mine 

'X' Manganese prospect 

e. High Head prospects 

f. Gap Mountian prospect 

• Measured section 

0 

0 10 

10 

20 

20 30 MILES 

30 40 KILOMETERS 

Sample localities-with 7.5-minute quadrangle map coverage and references for previously measured sections 

1. Baldwin Gap- Middletown quadrangle, Va. Webb and Nunan (1972, p. 60 and 64); Butts and Edmundson (1966, p.52); 

and Swartz (1929, p. 60-61) (Note: Swartz (1929) erroneously referred to this location as Fawcett Gap). 

2. Richards Run- Mountain Falls quadrangle, Va.-W.Va. Webb and Nunan (1972, p. 60 and 64); Butts and Edmundson 

(1966, p. 56-57). 

3. Paddy Run- Mountain Falls quadrangle, Va.-W.Va. In Paddy Run, east of the bridge on State Route 600, 2.8 miles northeast of Zepp. 

4. Liberty Furnace- Wolf Gap quadrangle, W.Va.-Va. In Laurel Run, 0.4 miles north of the intersection of State Routes 717 and 691, at 

Liberty Furnace. 

5. Fulks Run- Fulks Run quadrangle, Va. Webb and Nunan (1972, p. 118-1.19); Swartz (1929, p. 62); Woodward (1943, p. 201-202); 

and Woodward (1955, p. 9-10). 

6. Bonnet Hill- Wardensville quadrangle, W.Va. Located 0. 7 miles northwest of Zepp. 

7. High Head Prospects- Wolf Gap quadrangle, W. Va.-Va. Location published in Stose and Miser (1922, p. 90) 
Dorobek and Read (1986) Diecchio (1985) Young and Rader (1974) 

WESTERN MARYLAND SOUTHWEST VIRGINIA SOUTHWEST VIRGINIA NORTHWEST VIRGINIA 

Needmore Shale Huntersville Chert Onondaga Limestone Needmore Formation UJ Needmore Shale _J 

0 

0 -z z Oriskany Sandstone Oriskany Sandstone Ridgeley Sandstone Ridgeley Sandstone 

~<( ~ Shriver i_ ~Rocky Gap Rocky GapJ oz c::: Chert Licking Creek UJ Sandstone Sandstone (.!),.... 

zo 1- c:::C/) <C> (/) Mandat~ Limestone Licking Creek Limestone New Scotland Shale UJUl 

c:::UJ _J a.. a.. o:JZ Limestone UJO ::> Corriganville Corriganville Limestone ::> ::> c:::O 

s UJILimestone ~Healing Springs 0 0 C)(/) 

0 c::: c::: ....JUJ _J Sandstone (.!) (.!) UJ~ New Creek$ Elbow Ridge New Creek Limestone (.!) (.!) :::C- New Creek Limestone Limestone Sandstone c::: c::: _J 

UJ UJ Cl:J Cl:J z UpperKe~~ c::: c::: <( Limestone UJ UJ 

0: z Keyser 0 0 Clifton Forge _J _J Keyser Formation ::> <( UJ UJ _J (.!) Limestone Sandstone :::c :::c U5 ::> Big Mountain ), / 

c::: >- Shale 

UJ <( Lower Keys~ a.. u Limestone a.. 

::> Tonoloway Limestone Tonoloway Limestone Tonoloway Limestone 

Figure 3. Regional chronostratigraphic correlation chart showing rocks of Cayugan and Ulsterian age in the central 

Appalachian basin (Young and Rader, 1974; Diecchio, 1985; Dorobek and Read, 1986). 

is overlain by the Ridgeley Sandstone of the Oriskany 

Group in southwest Virginia and western Maryland. The 

Oriskany (Ridgeley) Sandstone is a near shoreline deposit 

(Dorobek and Read, 1986). The limestone-sandstone contact is observed in Richards Run and Fulks Run (fig. 2). 

The contact between the New Scotland and underlying Keyser Limestone of Silurian age is obscured at each 

locality sampled for this study. The Keyser Limestone is 

represented by deep ramp limestone or carbonate tidal flats 

(Dorobek and Read, 1986). 

Theories on the origins of supergene manganese 

concentrations over rocks of Devonian age in 

Virginia 

Hack (1965) best described the geochemical restrictions applicable to the manganese oxides in the weathered 

mantle over carbonate rocks in northwest Virginia. A brief 

summary of Hack, 1965, p. 70-76, follows: Manganese 

oxides and hydroxides can exist as solutes in fresh rain or 

stream water having an Eh of 0.3-0.5 and pH of 5.0-6.5. 

Where fresh water encounters carbonate rock, the carbonate 

dissolves and the alkalinity and the pH of the water rise. If 

the pH rises to 7 or the Eh drops below 0. 3, the manganese 

oxides and hydroxides can no longer remain in solution and 

precipitate out in the developing residuum of the host rock. 

Manganese phases already present in the carbonate 

rock exposed to weathering would also be trapped as 

insoluble residue in the alkaline geochemical environment. 

All theories on the origins of supergene manganese 

deposits in Virginia to date regard the host rocks as either 

( 1) deposition sites into which the manganese is brought and 

trapped or (2) as the parent rocks within which manganese 

is disseminated prior to in-situ weathering. There is growing evidence that the carbonate rocks of Cambrian and 

Ordovician ages may be regarded as deposition-site hosts 

(Force, this report, Chapter A), whereas the carbonate rocks 

of Devonian age may be parent rocks to the overlying 

manganese deposits. 

Parent rocks enriched in manganese by shallowmarine processes might give rise to supergene deposits 

constrained to the stratigraphic positions that had been 

occupied by the primary concentrations. So constrained are 

the supergene deposits in Cedar Creek Valley to the 

stratigraphic position occupied by the Upper Helderburg 

Group that Butts and Edmundson (1966) recommended: 

"since the proven occurrence of manganese in southwestern 

Frederick County occurs within the decomposed New 

Scotland Limestone immediately under the Oriskany Sandstone, any additional search or prospecting for manganese 

should first be restricted to areas where these rocks are 

present." Equally stringent stratigraphic limitations are not 

imposed on manganese deposits hosted by rocks that are 

84 Manganese Contents of Some Sedimentary Rocks of Paleozoic Age in Virginia 
enabled, largely by their geomorphological setting and 

carbonate make-up, to serve as deposition sites for manganese solutes in ground water. 

In Cedar Creek Valley the manganese mines are near 

the crests of low hills, 200-400 ft above the lowland of the 

valley (Monroe, 1942). Their hilltop positions preclude 

access to manganese sources from above, unlike the deposits over carbonate rocks of Cambrian age in the Shenandoah 

Valley (Hack, 1965). 

Hewett and others (1918) proposed that the source of 

manganese for residual deposits came from a widely disseminated carbonate phase in the dolomites and limestones, 

and possibly in the silicate phases in other rock types. No 

more specific mineral or rock sources were subsequently 

identified until recently, when zones of manganese-rich 

carbonate cements were identified by Dorobek ( 1987) in the 

Helderberg Group sediments. 

Dorobek (1987) noticed that differences in the luminescent properties of the carbonate cements in Helderberg 

Group limestones correspond to large differences in manganese content. Updip, brightly luminescent cements contain an average of 1, 164 ppm of manganese (Dorobek, 

1987); this is greater than 50 times as much manganese as 

in basinward, nonluminescent cements. Dorobek (1987) 

proposed that the geographic distribution of the manganeserich cements was determined by the distances meteoric 

ground waters traveled (as far as 90 mi) from the recharge 

areas on the eastern shore of the Appalachian basin in 

Devonian time. The cross section in figure 4 is taken from 

figure 11 in Dorobek ( 1987), which shows the basinward 

extent of brightly luminescent (manganese-rich) cements. 

It is likely that parent-rock hosts of manganese 

deposits are associated with fewer· structural and geomorphological settings than are the deposition-site hosts of 

manganese. The association of some deposits of Ordovician 

age with major faults, for example, suggests that the 

plumbing system is more important than the composition of 

the parent rocks in supplying manganese to the area (Force, 

this report, Chapter A). For the manganese deposits hosted 

by rocks of Cambrian age on the east side of the Shenandoah Valley, at the foot of the Blue Ridge, Hewett and 

others (1918) recognized at least five types of structural 

settings. Each serves as a favorable channel for groundwater circulation. Near-surface ( <300 ft) structural troughs 

of carbonate rock underlain by quartzite were thought 

superior to faults as favorable channels (Hewett and others, 

1918). 

Only one structural setting is described by Stose and 

Miser (1922) for the ores hosted by rocks of Devonian age 

in Cedar Creek Valley. There the deposits are especially 

numerous in areas where the limestones are repeated in 

synclinal folds that have brought the Devonian beds to the 

surface. Close folding appears to have shattered the rocks 

and created the fractures in the sandstones that the manganese oxides fill (Stose and Miser, 1922; Monroe, 1942). 

Tightly folded rocks have more fractures through which 

solutions, important to the dissolution of the host rock, can 

circulate freely. 

Deposits of manganese oxides parallel to bedding 

have also been recognized in steeply dipping Ridgeley 

Sandstone (Holden, 1936; Monroe, 1942; Young and 

Rader, 197 4). One expects that meteoric ground water 

traveling through permeable sandstone with manganiferous 

calcite cement will residually concentrate the manganese by 

the same geochemical processes as when it meets manganiferous carbonate cement in quartz-silty limestone. 

METHODS OF STUDY 

Field methods 

One hundred and two samples of limestone, chert, 

sandstone, and shale of Silurian and Devonian ages were 

collected from sections along strike from supergene manganese mines and prospects (fig. 2). Samples of unweathered Ridgeley Sandstone and New Scotland Limestone 

(uppermost in the Helderberg Group) were sought in particular. The best exposures were found in stream and 

roadside outcrops. 

Nearly complete sections were found at least 3 mi 

from the manganese mines. Samples of Ridgeley Sandstone, New Scotland Limestone, and Keyser Limestone 

were collected from the sections measured at Liberty 

Furnace (fig. 2, locality 4; fig. 5A), Fulks Run (fig. 2, 

locality 5; fig. 5B), and Richards Run (fig. 2, locality 2; fig. 

5C). 

Sampling of sections nearest the manganese deposits 

was incomplete because of the poor exposure of New 

Scotland Limestone. Samples of Romney Shale, rusty 

Ridgeley Sandstone, and Keyser Limestone were collected 

less than 3,000 ft north of the Mineral Ridge mine in Paddy 

Run (fig. 2, locality 3; fig. 5D), where a covered interval, 

225 ft wide, represents the New Scotland Limestone. 

Samples of Ridgeley Sandstone and Keyser Limestone were 

collected near the Bonnet Hill mine (fig. 2, locality c), 0.7 

mi northwest of Zepp. Three samples of Keyser Limestone 

were collected near the High Head prospects (fig. 2, locality 

e), 2.3 mi northwest of Columbia Furnace (fig. 2). Samples 

of the Keyser and Tonoloway Limestones were collected at 

Baldwin Gap (fig.2, locality 1; fig. 5E). 

Samples for chemical analyses were collected from 

each section so as not to miss any bed that might be at least 

3 ft thick and have > 1 weight percent manganese. Most 

sandstone samples were of single rocks representative of Ito 5-ft thicknesses of section. Most limestone samples were 

composites of 2-7 fresh chips taken over 10- to 20-ft-thick 

intervals, with each chip representing an apparently homogeneous interval of about 3-5 ft of exposed rock. Background concentrations near 130 ppm manganese were 

anticipated in the limestone and sandstone samples on the 

Manganese Contents of Some Rocks of Silurian and Devonian Ages in Northwest Virginia 85 
........ ..... . . . . •' 

..... 

.·.·.·. . . . . . . . . ... . . .. . . . ·. : ·.· ... . .. ·.-. . . . .. · ..... 

New Scotland Limestone 

*-* FEET METERS 

100LO 20 

O 10 10 20 MILES 

0 10 20 KILOMETERS 

EXPLANATION 

[:=J Area of distribution of nonluminescent cements with 

thin luminescent (bright and dull) laminae (Dorobek, 1987) 

~ Area of distribution of subzoned dull cement interlayered with 

thin luminescent (bright and dull) laminae (Dorobek, 1987) 

A 

39o15?rr9o....:.1.::..._5' __ ___:7r9o _______________ -;7Bo 

EXPLANATION 

'-" Manganese mine or prospect locality o Measured section locality 

B'/ 

Sector I 

"' 

/', 

' ' ) "'-,, 

(A' 

12dRichards Run 

WEST VIRGINIA hl 1o Baldwin Gap 

1 -x~·P Paddy Run 

I /'oZepp 

A/:.:' 1/ 

/1. ~~· VIRGINIA 

Petersburg Gap 

_/'-,~o Liberty Fumace 

Oak ) 5o Fulks Run 

Jlat/.J A 

I 

I 

J 

8 

5 10 15 MILES I I I 

5 1

1

0 1

1

5 KILOMETERS 

basis of analyses reported by McCue and others ( 1939) for 

equivalent rocks in West Virginia. With such low-level 

background values, a composite sample composed of at 

least one chip from a bed with greater than 0.1 weight 

percent manganese and no more than six chips with 0.01 

weight percent would probably contain a noticeable level of 

? Poor sample coverage (Dorobek, 1987) 

- Position of samples of New Scotland Limestone and 

Keyser Limestone collected for this report at localities 

1-5 along A-A' *-* Localities where bright luminescent cements were observed 

in this study 

Figure 4. Restored stratigraphic section (A) showing relative locations of studied sections (this report) and cathodoluminescent zonations of Dorobek (1987). Locations of 

sections from this study are superimposed on a cross 

section of the regional distribution of cathodoluminescent 

cement zones determined by Dorobek (1987, section E-E', 

fig. 11, p. 505) which passes through Oak Flat, Petersburg 

Gap, and Sector, W.Va., approximately 25 mi west of the 

study area. Map (8) showing the locations of measured 

sections along E-E' and A-A'. Sector, W. Va., is 25 mi N 

55 OW of the Paddy Run location. 

manganese (>300 ppm), thereby bringing attention to the 

sampled interval. 

Analytical methods 

Semiquantitative spectrographic analyses for 64 elements and quantitative inductively coupled plasma (ICP) 

spectrographic analyses for manganese, iron, barium, and 

phosphorous were completed in U.S. Geological Survey 

laboratories (Reston, Va.) for the 102 rock samples. This 

report contains the analytical data on 41 of the chemical 

elements (table 1). 

Petrographic methods 

Nine samples were studied with a petrographic microscope. Five of the samples were of Ridgeley Sandstone 

from the Richards Run, Paddy Run, and Liberty Furnace 

sections. Three of the samples were of New Scotland 

Limestone from Fulks Run (sample 053C, fig. 5B), 

86 Manganese Contents of Some Sedimentary Rocks of Paleozoic Age in Virginia 
Liberty Furnace section 0 400 800 1200 1400 ppm of Mn ~--------~,--------~,--------~,------~, 

031A 0318 =~§~~~· • 

0 

Q) 

c 

8 

!J) 

"'0 

c 

co 

CJ) 

> 

~ Q) 

Ol 

:"Q 

0:: 

z 

~~~~= ••, ?: i>r~: 0310- .: : · :-·· .: :·.:. :-· ·. • 

~ 

z ' 0 

> 

LU 1---

0 035A c:::><=:>c:::>c:::>c:::> 

<=:;) c=> c:::> c:::> c:::> c:::> • 0:: 

w 

s 0358 c:::>c:::>c::>c:::>c:::> 

c:::>c:::>c:::>c:::>c:::>c::> 0 c:::>c:::>c:::>c:::>c::> 

035C ·.··.· ·.·: ·· ·. ·· ·. · 0 

0 c:::><=:>c:::>c::>c:::>c:::> 

_J 

Q) c:::> c:::> c:::> c:::> c:::>IC 

c:::>c:::>c:::>c::>c:::>c:::> 

c c:::>c:::>c:::>c::>c:::> 

8 

!J) 

Q) 

0350- c:::>c::>c::>c::>c::>c:::> 

035E c:::>c:::>c:::>c::>c::> • • c::>c:::>c:::>c:::>c:::>c:::> 

c::>c:::>c:::>c:::>c:::> 

E 

::i 

"'0 

c 

c::>c:::><=:>c:::>c::>c::> 

c:::>c:::>c:::>c::>c:::> 

032A c:::>c::>c:::>c:::>c:::>c::> 

c:::>c::>c:::>c:::>c::> 0 c:::>c:::>c:::>c::>c:::>c:::> 

co A/ 

~ u 

CJ) 

5: 

Q) 

z o3f~~~) c:::>c::>c:::>c::>c::>c::> 

c::::>c::>c::>c:::>c:::> 

c::::::>c::>C:::::c::>c::>c::::> C{J 

03282CT c::::>c:::>c::>c::>c:::>c:::> 

o~~t~- ::;,c:::>c::>c::::>c::>c:::> 

032C10 • 032CT X' 

v / 

z Q) 

~ c 

8 0:: !J) 

~ Q) 

_J E CJ) ::i 0:: (ij LU 

c... !J) 

c... > 

Q) 

::J ~ 

• 

• 

EXPLANATION 

Manganese analyzed by atomic absorption spectrometry and 

reported in parts per million (ppm). 

SAMPLE TYPE 

e Single sample 

• Single chert 

0 Composite sample 

0 Composite chert 

Silver (Ag), barium (8a), zinc (Zn), 

molybdenum (Mo), neodymium (Nd), 

and cerium (Ce) analyzed by emission 

spectrometry and reported in parts 

per million (ppm). 

SAMPLE NO. ELEMENTS 

031A 

035A 

0358 

035C 

0350 

035E 

032A 

032C 

032C6 

032CT 

• 

• 

1.1 Ag, 9 Mo, 740 Nd 

.13Ag,1208a 

.17 Ag 

75 Zn, 1.9 Mo 

.25Ag 

14Mo 

.14Ag, 170 Nd, 130 Ce 

.11 Ag 

.12Ag 

.16Ag 

• 

LITHOLOGIES 

Limestone 

Shaly limestone 

Cherty limestone 

Chert 

Sandstone 

Covered 

Figure SA-f. Chronostratigraphic and lithostratigraphic sections of Paleozoic rocks in Virginia at Liberty Furnace, Fulks 

Run, Richards Run, Paddy Run, and Baldwin Gap, showing the manganese contents of the intervals sampled. Stratigraphic 

nomenclature applies to rocks in northwest Virginia. 

Figure SA. Section at Liberty Furnace. 

Richards Run (sample 012B, fig. SC), and Liberty Furnace 

(sample 032A, fig. SA). One sample was of chert containing 1 ,200 ppm of manganese from Liberty Furnace (sample 

032C, fig. SA). 

Highly polished sections were obtained of samples 

012B, 032A, and 032C to look at opaque and carbonate phases with the reflected light objectives on a petrographic microscope and the scanning electron microscope 

(SEM). The SEM was operated with the assistance of 

Elaine McGee (U.S. Geological Survey). Cathodoluminescence petrography was also done to look for brightly 

luminescent cements with a luminoscope, which was operated with the assistance of Jim Goss (U.S. Geological 

Survey). 

Manganese Contents of Some Rocks of Silurian and Devonian Ages in Northwest Virginia 87 
Fulks Run section Or-----___:_;400 ppm of Mn 

Q) 

c 

.8 

(/) 

z "0 

~ c 

co z (/) 

0 > > Q) 

w Q3 

0 0> 

c:: "0 

LU a: 

5 

0 

....J 

~ 

CQl 

~c 

-o o- U<ll 

CJ)Ql 

3: ~ Ol--' 

z 

053B053Cz Q) 

0::<( ._c 

Q)0 LU- (/)+-' c...C:: >(/) c..::> Q)Q) 

:::>::::! ~E 

055A055B055C- (/) :.:::i 055D -U-='=======-=::::::l 

Figure 58. Section at Fulks Run. 

• 

• 

0 

0 

0 

• 0 

RESULTS OF CHEMICAL ANALYSES 

0 

I5 FEET 

Manganese contents at each section (north to 

south) 

At Baldwin Gap (fig. 5£) manganese contents of the 

Keyser and Tonoloway Limestones of Silurian age are 

uniformly near 200 ppm for 260 ft of stratigraphic thickness 

in the upper part of the section. In the lower third of the 

section the manganese content averages 460 ppm where 

silty and cherty beds in the Tonoloway Limestone are 

encountered. 

At Richards Run (fig. 5C) manganese contents are 

highest in Romney Shale (290-480 ppm) and less than 250 

ppm in the section below the Romney Shale. Chert samples 

of the New Scotland Limestone contain only half (63, 69, 

and 24 ppm) the manganese of the limestone (120 ppm) 

wherever adjacent samples were collected in the section. 

At Paddy Run (fig. 5D) manganese contents are 

highest in samples collected at the contact of Ridgeley 

Sandstone ( 640 ppm in sandstone) with Romney Shale 

(1 ,600 ppm in shale). These samples are weathered and red 

from oxidized iron; the sandstone is brecciated at the 

contact. In contrast, unweathered, nonbrecciated sandstone 

28 ft below the contact contains only 17 ppm of manganese. 

At the Liberty Furnace section (fig. 5A) most samples 

contain less than 400 ppm of manganese, but the basal chert 

EXPLANATION 

Manganese analyzed by atomic absorption spectrometry and 

reported in parts per million (ppm). 

SAMPLE TYPE 

e Single sample 

• Single chert 

0 Composite sample 

Silver (Ag). molybdenum (Mol. 

barium (Bal. and cerium (Ce) 

analyzed by emission spectrometry 

and reported in parts per million (ppm). 

SAMPLE NO. ELEMENTS 

050A 

050B 

050C 

0500 

050E 

050F 

050G 

050H 

0501 

053A 

053B 

055B 

3.7 Mo 

5.7 Mo 

4.4 Mo 

4.8 Mo 

6.4 Mo 

4.2 Mo 

5.2 Mo 

6.0 Mo, .18 Ag 

5.5 Mo .. 19 Ag 

160 Ba 

.12Ag 

180 Ba,48 Ce 

LITHOLOGIES 

~Limestone 

~ Shaly limestone 

-

= = 

~ 

~ 

Cherty limestone 

Chert 

[::".:-.:.- /: :J Sandstone 

beds of the New Scotland Limestone contain 650-1 ,500 

ppm of manganese. These rocks are described in greater 

detail in the section titled "Manganese contents in the rocks 

of the Liberty Furnace section." 

At Fulks Run (fig. 5B) manganese contents are all 

below 400 ppm. As at Richards Run, interbeds of chert 

contain less manganese than the limestone beds. 

Manganese contents by lithology 

The ranges of manganese contents for limestones 

from the Keyser (20 samples) and New Scotland (16 

samples) Limestones are similar, from 81 to 360 ppm for 

the former and from 90 to 240 ppm for the latter. The 

Keyser Limestone has a mean manganese content of 187 

ppm (with one standard deviation of 68 ppm). This mean 

varies from section to section; for example, the mean is 137 

ppm in the north at Richards Run and is 225 ppm in the 

south at Fulks Run (fig. 2). The variation probably reflects 

the diversity of depositional environments represented by 

the Keyser Limestone. The mean manganese content of 

New Scotland Limestone is 152 ppm (with one standard 

deviation of 45 ppm) and is fairly consistent for each section 

sampled. 

Petrographic examination revealed that the high silica 

(> 11 weight percent, table 1) New Scotland limestones, 

between chert beds at Fulks Run and Richards Run, are free 

88 Manganese Contents of Some Sedimentary Rocks of Paleozoic Age in Virginia 
Richards Run section Or----~4T00~---~800ppmofMn I I 

~ 

co 

'

{ _____:::__ ___ --.:.:.:._ ___ __:::____::_ 

010A - _·_-_-·_·_· -··_· - ··· - ··· - · ·--

~---·-··· ··. :: · 

0 

..c 

en 

> 

Q) 

c 

E 

r-=--:-- ··· ... _:_:_:_ ... ... === ~ 

0108,C . •.• .•• · .•.•• 

·· - ··· _____:____ ___ _____:_:_:___ ___ .. 

0 

0 

c::: ,__ 

z Q) 

~ >c z ~0 

0 Q)+-' 

Olen 

> "'0"'0 w ·- c Cl c:::ro en 

• ~1~~\ ... ... . 011~· -:: : . · .• :.: .··. . . ,. • 

o1oF g~J&:P ·.' ·.::.··.·.··.·:·::. : : . ·.:.: e 0 o 010H1 . . . . . . 

a: 

w 

~ 1-----

0 012A 0 _J 

0128 ::>jc:=;J c::::l <=:! <==> <=>!C 0 "'0 

CQ) 

~c 

012C-1 • +-'0 

0+--

(.)(/) 

enQ) 

~.§ Q)_J 

0120 - c:=>c:::::>c::J<=>c:::::> 0 c=:>c=:>c::::>c=>c=><=> 

<:=:> c:::::> C:> c::::> c:::;, 

012E1)- c::>c::::lc::::lc::::lc=:>c::::> DO c:::::> c::::l c::> c:::> c:::::>IC 

012E2 c::>c:::::>c::::>c:::::>c::::>c:::::> 

=> l c::::> c::::> c::> c::> c:::> lc 

z c::::l <=:> c::::l c:::> c.::=> c:=> 

012F) <=>c::::lc:>c:::>c=:> 

012FCT 1- c::=J<=:::lc::::lc:=>c:::>c=:> DO IC:J <=> <=> c:=> c:::;, 

012G - ·.· . . .. . . • c:>c:::::>c::::lc:::::>c=>c:::::> 

013A) c=> c::::> <=> <=> <=> 

0138 D 0 <=> c::::> c::::> c:=;:. c:::::> c:::;:. 

c::> <=> c:::::> c::::> c::::> 

c::::> <=> c:::::> c:::;. c::::l c::::l 

<:::) c::;, c::::l c::::l c=> 

z Q) 

~ c 

B c::: (/) 

:::> Q) _J E en :.J a: (ij w 

(L (/) 

(L > 

Q) 

:::> ~ 

014 --{lc:::r::::c=cj:::q 0 

0 

I5 FEET 

Figure 5C. Section at Richards Run. 

of diagenetic chert and are instead siliceous because of their 

high silt-sized detrital grain contents. The detrital grains are 

mostly quartz with minor feldspar and detrital chert. Sample 

053C (Fulks Run) has nearly 50 percent detrital grains 

(mostly quartz) and has 130 ppm of manganese. Sample 

012B (Richards Run) has nearly 10 pecent detrital grains 

(mostly quartz) and has 240 ppm of manganese. The 

high-silica limestones at Liberty Furnace (sample 032A) do 

contain diagenetic chert that has replaced part of its calcite 

cement. Sample 032A has the lowest manganese (96 ppm) 

EXPLANATION 

Manganese analyzed by atomic absorption spectrometry and 

reported in parts per million (ppm}. · 

SAMPLE TYPE 

e Single sample 

0 Composite sample 

D Composite chert 

Zinc (Zn), silver (Ag), barium (8a), 

molybdenum (Mo), cerium (Ce). and 

neodymium (Nd) analyzed by emission 

spectrometry, reported in parts per 

million (ppm). 

SAMPLE NO. 

OlOE 

011A 

0118 

0110 

012A 

0128 

012E1 

012E2 

012FCT 

013A 

0138 

ELEMENTS 

220Zn 

150Zn 

36 Zn, 370 Ce, 190 Nd 

35Zn 

7.7 Mo 

1600 Zn 

12 Mo 

130 Zn, 770 8a 

360 Zn, .11 Ag 

.14Ag 

61 Ce 

LITHOLOGIES 

Limestone 

Cherty limestone 

Sandstone 

Siltstone 

I ;;; 0'1 Covered 

of the three limestones. The petrographic observations 

imply that manganese occurs in the carbonate phases of the 

New Scotland Limestone, most likely in the calcite cements 

rather than in detrital grains or chert. 

No manganiferous phases were discovered during 

petrographic and SEM examination of the limestones. 

However, thin laminae of cement were observed to luminesce bright orange and yellow under the luminoscope in 

samples 012B and 032A. This is an indication of higher 

than normal manganese content and is evidence that the 

Manganese Contents of Some Rocks of Silurian and Devonian Ages in Northwest Virginia 89 
Paddy Run section 0r-------~4T00~------~80r0 ________ ~12T0~0 ______ ~1~600ppmofMn 

.!!?--1--

r----

.r::. "' 

(j) 

> 

Q) 

E 0400 0 

a: 

Q) 

c 

.8 

(/) 

"'0 

c 

ro 

(/) 

> z ~ 

~ Q) 

O'l 

z "'0 

0 a: > 

UJ 

0 

a: 

l.LJ 

s 

0 

.....J 

-

"0 

CQ) 

~c 

+-'Q o ..... U(f) 

(J)Q) 

~.~ Q).....J 

z 

z Q) 

c ~ .8 a: (/) 

042A 

~ Q) 

.....J E 

U5 :.:i 042B a: ..... 

l.LJ Q) 

(/) a.. > a.. Q) 

~ ~ 

042C 

Figure 50. Section at Paddy Run. 

• 

0 

0 

0 

• • 

• 

I5 FEET 

regional distribution of cathodoluminescent cement zones 

determined by Dorobek ( 1987) may extend at least beneath 

the Liberty Furnace and Richards Run areas (fig. 4). 

The manganese contained in Romney Shale varies 

from 120 to 1,600 ppm of manganese. 

The manganese contained in Ridgeley Sandstone 

varies from 8 to 640 ppm; where values exceed 400 ppm, 

the rock is obviously weathered. 

The cherts collected from Fulks Run and Richards 

Run contained from 24 to 73 ppm of manganese. The cherts 

from Liberty Furnace contained from 100 to 1,500 ppm of 

manganese. The high manganese content of chert beds at 

Liberty Furnace are unusual, especially since these chert 

samples, unlike those collected from the other sections, 

contain more manganese than the adjacent samples of 

limestone. 

• 

EXPLANATION 

Manganese analyzed by atomic absorption spectrometry and 

reported in parts per million (ppm). 

SAMPLE TYPE 

e Single sample 

0 Composite sample 

LITHOLOGIES 

~Limestone 

1.::-::.:::: J Sandstone 

b ••• = H.j Siltstone 

Covered 

MANGANESE CONTENTS IN THE ROCKS OF 

THE LIBERTY FURNACE SECTION 

Field and chemical observations 

A 300-ft-thick section of Ridgeley Sandstone and 

New Scotland Limestone was measured and collected less 

than 0.4 mi northeast of the Old Iron Furnace in the Liberty 

Furnace area of Virginia. Liberty Furnace lies between two 

ridge-top manganese prospects. The Gap Mountain Prospect is 2 mi to the west and the High Head Prospect is 

3.5 mi to the northeast (fig. 2, localities f and e, respectively). Both prospects are at approximately 1,800 ft in 

elevation. At Liberty Furnace the Ridgeley Sandstone and 

New Scotland Limestone are exposed in a topographic gap 

occupied by Laurel Run at 1,300 ft in elevation. Exposures 

810 Manganese Contents of Some Sedimentary Rocks of Paleozoic Age in Virginia 
Baldwin Gap section 0 

I OOlCT 

DOlLS 

c:l <::::) c=> <:::::1 c::::::> c::::::> 

-

Q) 002 -

c 

.8 

(/) 003 Q) -

E 

:.J 

"- 005 -

Q) 

(/) 

> Q) 

~ 

006 -

f-----

009A -

009C -

z 

~ ~ 

0: 

:::::> 009E _J 

U5 

0: Q) 

w c a... .8 009G a... (/) 

:::> Q) 

E 

:.J 

> 009H ro 

:;: 

0 

0 ::>c::::::>c:::>c::::::>c::::::>c::::::> 

c:::::>c=>c::::::>c::::::>c::::::>c=:> 

c 

0 0091 - ::> i e=> c:=> C=> c:::::> c:::> 

I009J { ====== 

~=~=~=~ ~=~= 

009K { 

009L -

400 

I 

D 0 

0 

0 

0 

0 

0 

0 

0 

• 

• 

0 

0 

0 

0 

800 ppm of Mn 

I 

EXPLANATION 

Manganese analyzed by atomic absorption spectrometry and 

reported in parts per million (ppm}. 

SAMPLE TYPE 

e Single sample 

0 Composite sample 

D Composite chert 

LITHOLOGIES 

M Limestone 

- Cherty limestone 

~Chert 

t ·· .. ~%: j Covered 

I5F EET 

Figure 5£. Section at Baldwin Gap. 

of the New Scotland Limestone are poor in other topographic gaps between the prospects. 

A short section (approximately 300 ft) of the Ridgeley Sandstone and New Scotland Limestone beds exposed 

in Laurel Run (shaded area on fig. 6) are not shown on the 

geologic map of the Wolf Gap quadrangle (Young and 

Rader, 1974). The beds in Laurel Run strike north-south, 

(strikes range N13W to NS), dip steeply to the west 

( 65-70°), and form the shared common limb of a local 

subsidiary syncline-anticline couplet that is situated on the 

tightly folded western limb of a large, regional, southplunging syncline (fig. 6). 

The section measured at Liberty Furnace consists of 

150ft of Ridgeley Sandstone (95 ft exposed) overlying 150 

ft of New Scotland Limestone (110ft exposed, fig. 5). The 

median manganese content for 13 sandstone samples is 40 

ppm with most samples containing 18-62 ppm of manganese. 

At the top of the measured Liberty Furnace section, 

the manganese content of 031A (fig. 5A) is less than the 

detection limit of the method of analyses (10 ppm), 

although the rock is pyritiferous and highly anomalous in 

phosphorous and rare earth elements (fig. 5A). The two 

sandstone samples collected stratigraphically below the 

sulfidic zone contain four times as much manganese (031 B 

with 310 ppm and 031C with 260 ppm, fig. 5A) as the rest 

of the sandstone in the section. One explanation for the 

pattern observed here is that the local redistribution of 

manganese resulted in an enriched zone beneath a depleted 

zone. 

There is a 33-ft covered interval between the last 

outcrop of Ridgeley Sandstone and the first outcrop of 

Manganese Contents of Some Rocks of Silurian and Devonian Ages in Northwest Virginia 811 
Table 1. Results of analyses of rock samples 

[The semiquantitative direct current arc emission spectrographic (S) method of analyses of silicon, aluminum, iron, magnesium, calcium, sodium, 

potassium, titanium, and phosphorus are reported in weight percent(%); the amounts of all other elements determined by the semiquantitative direct current 

arc emission spectrographic method are given in parts per million (ppm). Analyses of 84 samples were conducted by C. Skeen, U.S. Geological Survey 

Laboratories, Reston, Va.; analyses of 18 samples were conducted by C. Skeen and Z. Brown. The quantitative inductively coupled plasma (ICP) 

spectrographic analyses of iron are reported in weight percent(%); the amounts of manganese, barium, and phosphorous determined by ICP are given in 

ppm. Analyses of samples were conducted by W. d'Angelo, U.S. Geological Survey Laboratories, Reston, Va. 

Symbols and abbreviations used in the table include: > , amount detected is greater than the upper limit of determination; <, amount detected is below 

the lowest limit of determination (which is the number preceding "<"); and -, not detected. 

Of the 64 elements looked for spectrographically, 31 elements were mostly not found and have been omitted from the table. The omitted elements (with 

the detection limits in ppm following each element in parenthesis) are: arsenic (100), gold (6.8), bismuth (10), cadmium (32), dysprosium (22), erbium 

(4.6), europium (2.2), gadolinium (32), germanium (4.6), hafnium (15 and 150), holmium (6.8), indium (10), iridium (15), lithium (68), lutecium (15), 

osmium (15), palladium (1.0), praesodymium (100), platinum (2.2), rhenium (10), rhodium (2.2), ruthenium (2.2), antimony (68), samarium (10), 

tantalum (320), terbium (32 and 46), thorium (46), thallium (10), thulium (4.6), uranium (220 and 460), and tungsten (15). Eight elements listed above 

were found as follows: sample 031A, 80 ppm dysprosium, 29 ppm erbium, 27 ppm europium, 21 ppm holmium, 150 ppm praesodymium, and 51 ppm 

samarium; sample 032A, 55 ppm thorium; sample 031K, 31 dysprosium; sample 034, 230 ppm lithium; sample 035B, 53 ppm thorium; sample 035D, 71 

ppm thorium; sample 039A with 3.4 ppm europium; and sample OllB, 19 samarium.] 

Sample Rock type 5i %-S AI %-S Mg %-S Ca %-5 Na %-S K %-5 Ti %-S Ag PPM-S B PPM-5 

Baldwin Gap 

OOlCT cherty limestone >34.00 .15 .40 14 .07 .13 .007 <.10 8.0 

OOILS limestone 9.50 .27 .65 >32 .04 .29 .011 <.10 <3.2 

002 limestone 1.30 .20 .62 >32 .04 <.07 .020 <.10 <3.2 

003 limestone 4.50 1.00 2.30 >32 .08 .36 .050 <.10 <3.2 

005 limestone 1.60 .12 .55 >32 .04 .30 .017 <.10 <3.2 

006 limestone 2.50 .28 .71 >32 .05 .26 .017 <.10 <3.2 

009A limestone 7.60 2.80 3.20 >32 .16 .77 .140 .13 17.0 

009C limestone 5.00 1.60 2.40 >32 .08 .51 .063 <.10 8.3 

009E limestone 6.10 1.90 3.00 >32 .07 .60 .078 .11 11.0 

009G limestone 7.90 2.40 1.80 >32 .11 .84 .140 .10 25.0 

009H limestone 7.10 3.00 2.30 >32 .14 .81 .110 .11 14.0 

009! cherty limestone 11.00 2.70 8.60 >32 .17 .79 .160 .13 21.0 

0091 cherty limestone 13.00 2.20 2.30 >32 .20 .64 .110 .10 9.1 

009K limestone 7.90 2.60 2.80 >32 .20 .96 .200 .19 21.0 

009L limestone 8.80 2.20 2.50 >32 .19 .88 .160 .16 33.0 

Richards Run 

010A siltstone 31 .00 16.00 2.20 2 .44 6.20 .610 .11 170.0 

OIOBC siltstone 30.00 17.00 2.20 1 .55 7.00 .440 .15 160.0 

010D claystone 3LOO 16.00 1.70 1 .13 7.00 .490 .26 210.0 

010E argil-ss >34.00 1.60 .15 0 .03 .35 .086 .15 51.0 

OIOF calc-ss >34.00 .67 .06 3 .01 .08 .048 .11 13.0 

011A argil-ss >34.00 2.20 .18 0 .03 .42 .100 .11 66.0 

011B calc-ss >34.00 1.70 .13 2 <.01 .29 .067 <.10 34.0 

OllD calc-ss >34.00 .53 .05 2 .01 .08 .036 <.10 13.0 

OlOG sandstone >34.00 .27 .03 0 <.01 <.07 .047 <.10 7.9 

OlOH sandstone >34.00 .35 .03 0 .01 <.07 .040 .10 19.0 

012A limestone 7.50 .73 .61 >32 .07 .39 .027 <.10 <3.2 

012B cherty limestone >34.00 .56 .27 12 .21 .19 .020 <.10 13.0 

012C limestone 4.00 .99 1.30 >32 .06 .42 .043 <.10 7.3 

012D cherty limestone 14.00 1.30 .76 >32 .06 .48 .049 <.10 11.0 

012E1 cherty limestone 11.00 1.20 . 57 >32 .10 .41 .050 <.10 . 12.0 

012E2 chert >34.00 .53 .14 1 .06 .11 .022 <.10 49.0 

012FCT chert >34.00 1.10 .74 9 .09 .24 .038 .11 40.0 

012F cherty limestone 26.00 1.90 1.40 27 .17 .59 .076 <.10 29.0 

012G argil-calc-ss >34.00 1.40 .29 3 .14 .41 .160 .13 23.0 

013A limestone 7.40 2.40 1.30 >32 .13 .76 .077 .14 21.0 

013B chert >34.00 .41 .06 0 .05 .11 .020 <.10 75.0 

014 limestone 10.00 4.30 2.10 >32 .09 1.40 .210 <.10 42.0 

015 limestone 3.00 1.70 1.20 >32 .05 .56 .055 <.10 <3.2 

018 limestone 1.80 .69 1.50 >32 .06 .39 .033 <.10 <3.2 

020 limestone 12.00 .87 .54 >32 .05 .40 .035 <.10 5.5 

812 Manganese Contents of Some Sedimentary Rocks of Paleozoic Age in Virginia 
Table 1. Results of analyses of rock samples-Continued 

Sample Rock type Si %-5 AI %-5 Mg %-5 Ca %-5 Na %-5 K %-5 Ti %-5 Ag PPM-5 B PPM-5 

Liberty Furnace 

031A shaly limestone 17.00 3.20 .36 >32 .16 .84 .130 1.10 48.0 

031B sandstone >34.00 .58 .05 0 .01 .12 .040 .14 20.0 

031C sandstone >34.00 .62 .04 0 .01 .20 .036 <.10 24.0 

031D sandstone >34.00 .64 .03 0 .01 .18 .043 <.10 16.0 

031E sandstone >34.00 .86 .05 0 .02 .30 .065 <.10 32.0 

031F sandstone >34.00 .69 .03 0 .01 .19 .060 <.10 26.0 

031G sandstone >34.00 .58 .04 0 .02 .25 .049 <.10 24.0 

031H sandstone >34.00 .24 .02 0 .01 .16 .017 <.10 9.4 

0311 sandstone >34.00 .11 .01 0 <.01 <.07 .017 <.10 14.0 

031K sandstone >34.00 .41 .03 0 .01 .09 .031 <.10 22.0 

031L sandstone >34.00 .41 .03 0 .01 .14 .030 <.10 16.0 

031M sandstone >34.00 .37 .03 0 .01 .17 .034 <.10 19.0 

031N sandstone >34.00 .53 .03 0 .01 .21 .039 <.10 18.0 

0310 sandstone >34.00 .45 .03 0 .03 .16 .052 <.10 19.0 

035A cherty limestone >34.00 2.50 .39 18 .45 .84 .100 .13 34.0 

035A2 cherty limestone 13.00 5.30 2.70 >32 .09 2.20 .250 <.10 59.0 

035B cherty limestone >34.00 2.40 .48 22 .42 .82 .089 .17 41.0 

035C argil-calc-ss >34.00 2.40 .33 11 .55 1.20 .150 .16 45.0 

035C86 argil-ss >34.00 1.90 .09 0 .02 .62 .250 .20 82.0 

035D cherty limestone 30.00 2.10 .50 29 .23 .82 .130 .25 27.0 

035E cherty limestone >34.00 1.90 .46 25 .25 .72 .120 <.10 46.0 

032A cherty limestone >34.00 2.10 .50 21 .18 .67 .140 .14 66.0 

032B cherty limestone 12.00 .71 .38 28 .02 .34 .034 <.10 8.5 

032BCT chert >34.00 .42 .13 5 .01 .11 .018 <.10 34.0 

032B2C chert >34.00 .46 .06 0 .01 .14 .023 <.10 36.0 

032C chert >34.00 .33 .05 0 .01 .12 .016 .11 41.0 

032C6 chert >34.00 .67 .07 0 .01 .15 .028 .12 66.0 

032C10 chert >34.00 .68 .07 0 .02 .16 .051 <.10 61.0 

032CT chert >34.00 1.00 .13 0 .01 .20 .041 .16 82.0 

034 shaly limestone 16.00 5.20 1.60 16 .05 1.70 .250 <.10 79.0 

Paddy Run 

039A siltstone 26.00 14.00 1.10 0 .09 4.50 .290 <.10 190.0 

039B siltstone 23.00 12.00 .75 0 .12 6.00 .470 .37 170.0 

040A sandstone 22.00 .88 .05 1 .10 <.07 .093 .65 16.0 

040B sandstone >34.00 .40 .02 1 .01 <.07 .032 <.10 7.2 

040C sandstone >34.00 .17 .02 0 <.01 <.07 .026 <.10 5.8 

040D sandstone >34.00 .08 .01 0 <.01 <.07 .010 <.10 <3.2 

042A limestone 3.50 2.50 1.60 >32 .06 .77 .083 <.10 5.3 

042B limestone 3.90 1.50 2.10 >32 .06 .51 .061 <.10 <3.2 

042C limestone 8.90 3.30 1.60 >32 .14 1.40 .180 <.10 28.0 

High Head Prospects 

045A limestone 2.20 .08 .44 >32 .02 .27 .008 <.10 <3.2 

045B cherty limestone 23.00 2.20 .67 18 .12 .84 .100 <.10 23.0 

045C limestone 8.10 2.70 1.50 >32 .13 1.10 .140 <.10 25.0 

Fulks Run 

050A sandstone >34.00 .56 .03 0 .03 .16 .031 <.10 7.2 

050B sandstone >34.00 .66 .03 0 .01 .17 .045 <.10 19.0 

050C sandstone >34.00 .78 .03 0 .06 .30 .037 .11 11.0 

959D sandstone >34.00 1.40 .06 0 .10 .56 .053 <.10 28.0 

050E sandstone >34.00 1.10 .04 0 .10 .30 .150 <.10 46.0 

050F sandstone >34.00 1.50 .07 0 .31 .55 .130 <.10 58.0 

050G sandstone >34.00 3.00 .15 0 .43 .83 .220 .10 65.0 

050H sandstone >34.00 1.80 .14 0 .01 .49 .360 .18 120.0 

050IS sandstone >34.00 1.80 .12 0 .01 .31 .260 .19 83.0 

Manganese Contents of Some Rocks of Silurian and Devonian Ages in Northwest Virginia 813 
Table 1. Results of analyses of rock samples-Continued 

Sample Rock type Si %-5 AI %-5 Mg%-5 Ca %-5 Na %-5 K %-5 Ti %-5 Ag PPM-5 B PPM-5 

Fulks Run -Continued 

050IC chert >34.00 .26 .01 0 .01 <.07 .008 <.10 48.0 

0501 chert >34.00 .22 .02 0 .01 <.07 .009 <.10 62.0 

053A cherty limestone 26.00 1.80 .41 10 .34 .75 .092 <.10 20.0 

053B cherty limestone 23.00 1.60 .41 15 .25 .55 .059 .12 19.0 

053C cherty limestone 22.00 1.20 .39 18 .19 .41 .076 <.10 45.0 

055A limestone 1.90 1.20 1.10 >32 .04 .57 .038 <.10 <3.2 

055B shaly limestone 16.00 4.10 1.60 16 .08 2.60 .170 <.10 95.0 

055C limestone 1.40 .06 .51 >32 .03 .24 <.003 <.10 <3.2 

055D shaly limestone 12.00 3.00 1.30 >32 .13 .91 .130 <.10 16.0 

Bonnet Hill 

060A limestone .47 .13 .48 

060B sandstone >34.00 .17 .01 

limestone of the New Scotland Limestone. The limestones 

are dark gray and interbedded with chert bands of variable 

width. The limestones are composed of approximately 

10-40 percent sand-sized detrital grains (mostly quartz) in a 

matrix of micritic carbonate mud. The manganese contents 

of the limestones steadily decrease from 240 ppm at the top 

to 90 ppm near the bottom of the section (those beds above 

the massive chert beds) as the limestones become increasingly cherty (fig. 5). The chert bands are parallel to bedding 

in the limestone and vary from stringers of black chert 

fragments to beds of irregular knots (generally 6 in across) 

of mostly black chert at the top of the section to 5-ft-thick 

beds of massive grayish-white to bluish-black chert at the 

base of the section. 

The highest manganese contents ( 650-1 , 500 ppm) in 

the Liberty Furnace section were found in four samples of 

chert in the lowermost 30 ft of the New Scotland Limestone 

(fig. 5). Three of the six chert samples contain 1,200-1,500 

ppm of manganese (fig. 5). The concentration of manganese here is in part attributed to the axial position of the 

cherts in the syncline and the circulation of ground water 

through the fractures associated with the tight synclinal 

folding. 

Petrographic observations 

Several grains of hematite were identified in chert 

from Liberty Furnace (sample 032C, fig. 5A), but no 

manganese phases were observed in the hematite or in the 

other grains examined petrographically and with the SEM. 

The distribution of the unidentified manganese phase may 

be analogous to the distribution of the hematite. Hematite 

(at most, 0.54 weight percent) is generally clustered in one 

region, which takes up less than a thousandth of the area 

seen in thin section. Manganese may be present in these 

cherts as a discrete, heterogeneously disseminated phase 

that escaped intersection by the thin section. One can 

>32 .03 .30 .013 <.10 <3.2 

0 <.01 <.07 .020 <.10 <3.2 

assume that the chance of missing phases of such small 

concentration and uneven distribution in thin section is 

great. 

Redistribution of manganese in carbonate cements 

may have been facilitated by rock porosity and permeability 

created by pressure-dissolution and tectonic fractures. Some 

of the features (observed in thin section) that give information on the changes in porosity and permeability of the rocks 

since early diagenesis include: 

1. Oxidized minerals. Spherical pyrite framboids are found 

interstitial to quartz grains in sample 032A (fig. 5A). 

The framboids grew in a reducing environment, which is 

also suitable for manganese concentration. Many of the 

smallest framboids are replaced by hematite. Replacement apparently proceeded from the outer rims inward, 

as the largest framboids have only a few hematite cells 

on the outermost rim. Replacement of pyrite occurred 

while the limestone was permeable to oxidizing (fresh) 

water, otherwise the interiors of the largest framboids 

would also be oxidized. Fresh water may remove and 

redistribute manganese, thus the low manganese level 

(96 ppm) in sample 032A. 

2. Crushed grains. Dissolution of original carbonate material by fresh water is implied where there are crushed 

marine ooids, ooid molds filled with calcite cement, and 

secondary calcite growths on grains (Bathurst, 1986). 

All three are seen in sample 032A. 

3. Stylolites. Dissolution of original material is evident 

where stylolites cross the chert (sample 032C, fig. 5A). 

The stylolites enclose bands of insoluble (noncarbonate) 

residues that were concentrated upon removal of original 

material. 

4. Silicified fragments. Dissolution of original carbonate 

material is evident where chert replaces echinoderm 

ossicles in the cherty limestone and chert near basal New 

Scotland Limestone (samples 032A and 032C, fig. 5A). 

In contrast, the bioclastic fragments in the limestones at 

814 Manganese Contents of Some Sedimentary Rocks of Paleozoic Age in Virginia 
Old Iron-. ._ Furnace '\Liberty 

Furnace 

38°52'3Q"L-I ___________________ _j 

Base modified from U.S. Geological Survey Geology from Young and Rader Wolf Gap, 1966 (1974) except where shaded 

DEVONIAN 

1 KILOMETER 

CONTOUR INTERVAL 200 FEET 

EXPLANATION 

B Needmore Formation 

~ Ridgeley Sandstone 

~ New Scotland Limestone 

1 MILE 

SILURIAN ~ Keyser Formation 

D Section not shown on Young and Rader (1974) 

--Contact-Dashed where approximate or concealed 

_f_ Strike and dip of beds 

Figure 6. Outcrop map of the Ridgeley Sandstone and 

New Scotland Limestone near Liberty Furnace, Va. 

Fulks Run and Richards Run appear to be original 

material. The silicified fossils indicate that the massive 

chert beds were at one time limestone beds. 

5. Tectonic fractures. Permeability was enhanced by more 

than one generation of fractures. In the chert (sample 

032C, fig. 5A), fractures are filled with mosaic quartz 

and are cross-cut by diffusely bounded channels of dirty 

amorphous chert. Hairline fractures with minor offsets 

bisect silicified echinoderm ossicles, indicating that the 

silicification preceeded later deformation. Repeated tectonic fracturing increased the opportunity for the passage 

of ore-scavanging or ore-bearing solutions. 

DISCUSSION 

Fresh samples of limestone and sandstone hosts and 

parents to supergene manganese deposits generally contain 

from 100 to 400 ppm of manganese. The manganese is 

thought to be locally concentrated in thin laminae of the 

calcite cement (primary). Limestone beds in which silica 

has pervasively replaced calcite and in which permeability 

has been enhanced by tectonic fracturing are slightly 

enriched in manganese ( 650-1 ,500 ppm). The manganese is 

thought to occur as discrete, heterogeneously disseminated 

oxide phases (secondary). 

The composition of the calcite cement and local rock 

permeability may be the major factors in residual concentration of manganese. As manganiferous cement was dissolved by pressure-dissolution or in the process of silicification, the manganese ions remained in place as insoluble 

residues. Late Paleozoic deformation and subsequent erosion brought the beds to the surface where weathering of the 

carbonate left insoluble chert, sandy clay, and manganese 

or iron oxides in place of the original beds. Tectonic 

fractures enhanced the permeability of the cherts, which at 

times increased their favorability as hosts for manganese 

concentrations. 

HYPOTHESIS OF MANGANESE ENRICHMENT 

There are zones of brightly luminescent-highly manganiferous cements in limestones of the upper Helderberg 

Group, that were deposited near the eastern shore of the 

Devonian Appalachian basin (Dorobek, 1987). Dorobek 

( 1987) suggests that these zones are fixed and limited in 

geographic distribution by the distances meteoric ground 

waters traveled from the recharge areas exposed in Devonian time. Accordingly, reconstruction of the basin geometry and the location of the recharge areas should enable one 

to locate the zones of manganese-rich carbonate cement. 

The author suspects there is a correlation between the 

location of supergene manganese deposits and the paleozone corresponding to the limit of travel of the reduced 

meteoric ground water. Further study should be made to 

confirm that the supergene manganese deposits in this study 

area are underlain by zones of manganese-rich carbonatecement. 

REFERENCES CITED 

Bathurst, R.G.C., 1986, Carbonate diagenesis and reservoir 

development: conservation, destruction, and creation of pores 

in Warme, J.E., and Shanley, K.W., eds., Carbonate depoManganese Contents of Some Rocks of Silurian and Devonian Ages in Northwest Virginia 815 
sitional environments-modem and ancient: Colorado School 

of Mines Quarterly, v. 81, no. 4, p. 1-25. 

Brent, W.B., 1960, Geology and mineral resources of Rockingham County: Virginia Division of Mineral Resources Bulletin 

76, 174 p., map scale 1:62,500. 

Butts, Charles, and Edmundson, R.S., 1966, Geology and mineral 

resources of Frederick County: Virginia Division of Mineral 

Resources Bulletin 80, 142 p., map scale 1:62,500. 

Calver, J.L., and Hobbs, C.R.B., 1963, Geologic map of Virginia: Virginia Division of Mineral Resources, map scale 

1:500,000. 

Diecchio, R.J., 1985, Regional controls of gas accumulations in 

Oriskany Sandstone, Central Appalachian Basin: The American Association of Petroleum Geologists Bulletin, v. 69, 

no. 5, p. 722-732. 

Dorobek, S.L., 1987, Petrography, geochemistry, and origin of 

burial diagenetic facies, Siluro-Devonian Helderberg Group 

(Carbonate Rocks), central Appalachians: The American 

Association of Petroleum Geologists Bulletin, v. 71, no. 5, 

p. 492-514. 

Dorobek, S.L., and Read, J.P., 1986, Sedimentology and basin 

evolution of the Siluro-Devonian Helderberg Group, central 

Appalachians: Journal of Sedimentary Petrology, v. 56, 

no. 5, p. 601-613. 

Force, E.R., and Cannon, W.F., 1988, Depositional model for 

shallow-marine manganese deposits around black shale 

basins: Economic Geology, v. 83, no. 1, p. 93-117. 

Hack, J.T., 1965, Geomorphology of the Shenandoah Valley, 

Virginia and West Virginia, and origin of the residual ore 

deposits: U.S. Geological Survey Professional Paper 484, 

84 p. 

Hewett, D.F., Stose, G.W., Katz, F.J., and Miser, H.D., 1918, 

Possibilities for manganese ore on certain undeveloped tracts 

in the Shenandoah Valley, Virginia: U.S. Geological Survey 

Bulletin 660-J, p. 271-296. 

Holden, R.J., 1936, Origin of the Oriskany iron and manganese 

ores in Bevan, Arthur, ed., Contributions to Virginia Geology: Virginia Geological Survey Bulletin 46, p. 31-34. 

McCue, J.B., Lucke, J.B, and Woodward, H.P., 1939, Limestones of West Virginia: West Virginia Geological Survey 

Bulletin 12, 560 p. 

McGill, W.M., 1936, Outline of the Mineral Resources of 

Virginia: Virginia Geological Survey Bulletin 47, 81 p. 

Monroe, W.H., 1942, Manganese deposits of Cedar Creek Valley, Frederick and Shenandoah counties, Virginia: U.S. 

Geological Survey Bulletin 936-E, p. 111-141, pl. 13, map 

scale 1:24,000. 

Rader, E.K., and Biggs, T.H., 1976, Geology of the Strasburg 

and Toms Brook quadrangle, Virginia: Virginia Division of 

Mineral Resources Report of Investigations 45, 104 p., pis. 

1 and 2, map scale 1:24,000. 

Stose, G.W., and Miser, H.D., 1922, Manganese deposits of 

western Virginia: Virginia Geological Survey Bulletin 23, 

206 p. 

Swartz, F.M., 1929, The Helderberg Group of parts of West 

Virginia and Virginia: U.S. Geological Survey Professional 

Paper 158-C, p. 27-75. 

Webb H.W., Jr., and Nunan, E.W., 1972, Bibliography of 

published measured sections of the Blue Ridge in Virginia: 

Virginia Division of Mineral Resources Information Circular 

18, 219 p. 

Woodward, H.P., 1943, Devonian system of West Virginia: West 

Virginia Geological Survey Bulletin 15, 655 p. 

---1955, Harrisonburg to Bergton, in Fisher, C.C., ed., 

Guidebook joint field conference in the Harrisonburg area, 

Virginia: Appalachian Geological Society, p. 8-13, 34--39. 

Young, R.S., and Rader, E.K., 1974, Geology of the Woodstock, 

Wolf Gap, Conicville, and Edinburg quadrangles, Virginia: 

Virginia Division of Mineral Resources Report of Investigations 35, 69 p., pis. 1, 2, 3, and 4, map scale 1:24,000. 

816 Manganese Contents of Some Sedimentary Rocks of Paleozoic Age in Virginia 


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