GEOLOGICAL SURVEY CIRCULAR 711

tit

Preliminary Results of 

Geochemical Soil Survey, 

Hamme Tungsten District, 

North Carolina
Preliminary Results of 

Geochemical Soil Survey, 

Hamme Tungsten District, 

North Carolina

By Jacob E. Gair, John F. Windolph, Jr., 

and Nancy A. Wright

GEOLOGICAL SURVEY CIRCULAR 711

Trace-element values in soil are related to 

major underlying rock units and to tungsten 

mineralization and indicate a large 

bismuth-copper-molybdenum anomaly 

west of the principal mineral deposit

1975
United States Department of the Interior

ROGERS C. B. MORION, Secretary

Geological Survey

V. E. McKelvey, Director

Library of Congress Cataloging in Publication Data

Gair, Jacob Eugene, 1922-

Preliminary results of geochemical soil survey.

(Geological Survey circular; 711)

Bibliography: p.

Supt. of Docs, no.: I 19.4/2:711

1. Tungsten. 2. Geochemistry. 3. Ore-deposits North Carolina Vance Co. 

4. Soils North Carolina Vance Co. I. Windolph, John F.. joint author. II. 

Wright, Nancy A., joint author. III. Title. IV. Series: United States. Geological Survey. Circular. 711.

QE75.C5 no. 711 [QE516.W1] 557.3'08s [553'.464] 74-28240

Free on application to the U.S. Geological Survey, National Center, Reston, Va. 22092
CONTENTS

Patfe

Abstract ____________________________________ 1

Introduction _. _____ __________________ 1

Sample handling and analytical procedures _____________________ 4

Orientation survey ______________________________ 5

Traversing and sampling procedure _________________________ 5

Geochemical data ________________________________ 5

Contamination ________________________________ 5

High trace-element values ____________________________ 6

Distribution of high tungsten values ___________________________ 12

Area of high bismuth, copper, and molybdenum values ______________- 13

Border zone of pluton south of Hamme mine area __________________ 13

Conclusions _____________________________________________ 19

References cited ________________________________ 19

ILLUSTRATIONS

Patfe

FIGURE 1. Map showing location of soil-sampling traverses and principal

geologic features, Hamme tungsten district, North Carolina. _ 3

2. Diagrams showing comparison of trace-element values at 0- to 1-

foot (0-0.3 m) and 1- to 2-foot (0.3-0.6 m) depths ______ 8

3. Isopleth maps of geochemical data showing areas of high bismuth,

copper, and molybdenum values _______________________ 16

TABLES

TABLE 1. Examples of analytical data from two soil-sample traverses ____ 6

2. Trace-element statistics mean values, deviation, and arbitrary geochemical threshold in soil samples from granitic rock and 

phyllite areas _______________________________ 10

3. Clustering indexes in selected traverses of area A __________ 14

ill

Preliminary Results of Geochemical Soil Survey, 

Hamme Tungsten District, North Carolina

By JACOB E. GAIR, JOHN F. WINDOLPH, JR., and NANCY A. WRIGHT

ABSTRACT

The results of a geochemical soil survey above the 

Hamme tungsten deposit, North Carolina, indicate that 

geochemical exploration techniques are a workable but 

limited method for searching for tungsten in similar 

geologic environments elsewhere in the Piedmont. The 

principal tungsten mineral of the Hamme deposit, 

huebnerite, occurs in quartz veins associated with 

fluorite and commonly containing accessory pyrite, 

sphalerite, galena, and chalcopyrite, and, in places, 

tetrahedrite. Scheelite is minor. The mineralized veins 

trend mainly northeast in the marginal part of a 

granodiorite-tonalite pluton and in nearby metavolcanic phyllite of the Carolina slate belt. Vein quartz 

float containing huebnerite occurs in soil for as much 

as several hundred feet downslope from veins. The 

limit of detection for tungsten, 50 parts per million 

(spectrographic), constitutes an anomalously high 

value. Values of 50 parts per million to several hundred parts per million tungsten generally occur in soil 

samples taken directly over known mineralized veins 

or downslope from veins in areas containing quartz 

float. Tungsten is probably transported as particles 

of comminuted huebnerite. Therefore, geochemical evidence in soil for tungsten mineralization is likely to 

be found only where lenticular mineralized veins are 

near enough to the surface to be subject to mechanical 

weathering and where some quartz float occurs in the 

soil. High copper and molybdenum values occur in a 

belt about 2,000 feet (600 m) west of the principal 

tungsten deposit and apparently are related to a thick 

quartz vein. Soil samples also were taken 1 to 3 miles 

(1.6-4.8 km) south of the Hamme tungsten deposit, 

across the projection of the Hamme mineralized zone. 

These samples contain some clusters of high tungsten 

values.

INTRODUCTION

The Hamme district, North Carolina (fig. 1), 

is the only area in the eastern United States 

with a history of tungsten mining. The district 

has been a major producer since World War II 

and contains the largest known classic example

of wolframite-type quartz vein deposits in the 

United States. Tungsten was discovered in the 

Hamme district in 1942; mining began in 1943 

(Espenshade, 1947, p. 2-3) and was continued 

with -slight interruption until 1963, when it was 

stopped because of low prices. Mining was 

started again in 1970 by Ranchers Exploration 

and Development Corp., but it was stopped in 

the fall of 1971, after a sharp drop in the price 

of tungsten. Total production has been about 

1 million short ton units of WO3

Tungsten in the Hamme district occurs 

mainly in huebnerite, the manganese end member of the wolframite series, and in much lesser 

amounts in scheelite. The tungsten minerals 

occur within massive veins of white quartz occupying several subparallel and crossing zones 

near the west margin of an elongate northnortheast-trending granodiorite-tonalite pluton. 

Most production has come from veins in a 

north-northeast-trending sericitized shear zone 

within the granitic rock. Most of these veins 

dip steeply southeast (60°-80°). The southwestern part of the zone angles across the edge of 

the pluton into phyllite of the Carolina slate 

belt (Parker, 1963, p. 12, 62). Veins entirely 

within the slate belt rock have been a source 

of some tungsten production. Two thick 

diabase dikes of Triassic age trend northnorthwest and cut the mineralized veins and 

wall rocks. Other mineralized veins which 

diverge from the principal vein system or lie 

at a large angle to it generally trend west or 

northwest. Two of these veins have had some 

tungsten production. Less productive and barren quartz veins are parallel to and to the west 

of the main system or can be projected on strike
36°30'

TUNGSTEN QUADRANGLE .? 

TOWNSVILLE QUADRANGLE A
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1 KILOMETRE

CONTOUR INTERVAL 10 FEET 

DATUM IS MEAN SEA LEVEL

78a 30'

Base by U.S. Geological Survey, 

1968 and 1970

Geology modified from reports by 

Espenshade, 1947, and Parker, 1963

FIGURE 1. Map showing location of soil-sampling traverses (numbered) and principal geologic features, 

Hamme tungsten district, North Carolina. Quartz veins are shown in solid black; huebnerite occurs 

mainly in the principal mineralized vein system. The contact between the phyllite and granodioritetonalite is approximately located.
northeast and southwest from the main productive zone. The main productive zone, slightly 

more than a mile (1.6 km) long within area A 

in figure 1, and the subsidiary tungsten-bearing 

veins northeast and southwest of the zone occupy a belt about 8 miles (13 km) long which 

extends north of the map area (Espenshade, 

1947, p. 2). Veins in the main productive zone 

consist largely of en echelon quartz pods separated by thin septa of schist. Proceeding from 

northeast to southwest, the en echelon pods are 

offset westward. Buckles and drag folds within 

pods commonly plunge steeply south-southwest 

to south-southeast; this structure suggests 

that the gross form of the pods may be that of 

overlapping steeply plunging ribbons.

Accessory fluorite and sulfide minerals are 

common in the deposit (Espenshade, 1947, p. 

6-9). Pyrite is the most abundant sulfide by 

far in wall rocks near the veins as well as 

within the veins. Chalcopyrite, galena, and 

sphalerite are also common, and tetrahedrite 

is seen in some places in the veins. Molybdenite 

and rhodochrosite are comparatively rare. An 

unidentified mineral, common in films and tiny 

flakes in the quartz veins, fluoresces bright 

orange-red and may be pyromorphite of supergene origin (Espenshade, 1947, p. 8).

Chemical weathering has been intense in the 

area, and soil typically grades into saprolite. 

In mine workings, effects of weathering have 

been seen as deep as 50 to 75 feet (15-23 m) 

below the land surface.

Felsic plutons are known in the Piedmont of 

the southeastern United States (Butler and 

Ragland, 1969), but they have not been adequately evaluated as potential sources of mineralization. This study was initiated in 1970 

to apply normal techniques of geochemical exploration to determine in the southeast Piedmont environment the influence on trace elements in soils of a classic vein-type (tungsten) 

deposit associated with a felsic pluton. The results of this study suggest that such techniques 

could also be applied effectively to preliminary 

exploration of other felsic plutons in the Piedmont.

An orientation survey (area A in fig. 1) was 

conducted to establish normal ranges of values 

for trace elements in soil above known geologic

features and distribution patterns of trace elements in soil at various distances from the 

known mineralized veins. (For discussion of 

orientation surveys, see Hawkes and Webb, 

1962, p. 204.)

This report deals with as many as 12 of the 

30 or so trace elements determined in the orientation survey and in additional soil surveys 

(areas B and C) directly west of, and 1 to 3 

miles (1.6-4.8 km) south of, the main mineralized zone, along the west edge of the granitic 

pluton. The selected elements are those which, 

without detailed statistical analysis, appear to 

vary substantially either along traverses or 

from one part of the area to another. The selected elements are tungsten, copper, lead, zinc, 

beryllium, molybdenum, cobalt, nickel, chromium, and fluorine. Additionally, antimony is 

included for areas A and B, and bismuth for 

area B. Antimony was not analyzed for in 

area C; bismuth generally was not present in 

measurable amounts except in area B.

Fieldwork was done by Gair and Windolph, 

assisted in part by John D'Agostino. Computerized processing of geochemical data was 

done by Wright.

SAMPLE HANDLING AND ANALYTICAL 

PROCEDURES

Samples were ovendried and then broken up; 

they were ground where necessary to overcome 

baking together in the drying process. The 

broken-up and ground material was sieved, and 

the part that passed 80 mesh was saved for 

analysis. The samples were not ashed or analyzed for organic content.

All samples were analyzed by a semiquantitative spectrographic method in which values 

are reported in six geometric classes (Miesch, 

1967, p. B3-B4). Molybdenum and, in some 

traverses, antimony were also tested by 

colorimetric analysis; copper, lead, and zinc, by 

atomic absorption; and fluorine, by specific ion 

test. Although wet-chemical analysis may not 

necessarily agree closely with a spectrographic 

analysis for a particular element, corresponding low and high values are generally indicated 

regardless of the analytical method if the sensitivity of the method permits measurement of 

the element.
ORIENTATION SURVEY 

TRAVERSING AND SAMPLING PROCEDURE

The orientation soil survey consisted of 

sampling traverses to determine geochemical 

profiles across mineralized quartz veins and associated rocks (fig. 1, area A), especially the 

north-northeast-trending veins of the principal 

zone.

Traverses cross veins roughly at right angles 

and extend from several hundred feet to about 

1,500 feet (100-450 m) beyond any known 

vein in order to reach beyond the expected 

influence of the veins and to obtain background 

data on the trace-element content of soil and 

saprolite formed from granodiorite-tonalite and 

phyllite of the Carolina slate belt and Triassic 

diabase, the principal rock types cut by or cutting the veins. The selected analytical data for 

the traverses have been arranged in tables that 

simulate the distribution of sample values along 

a traverse (table 1; Gair and Windolph, 1975).

The common sampling interval along traverses is 50 feet (15.2 m). Samples were collected with a 1-inch (about 2.5 cm)-diameter 

soil auger. Two or three samples from different depths were taken from each auger hole to 

test whether different concentrations of trace 

elements occur at different levels in the soil 

profile and to compare such differences as might 

exist. Because of the difficulty of identifying 

horizons in the soil profile while augering 

the profile never being exposed to view sampling was done systematically according to distance from the surface rather than by soil horizon. In collecting three samples from an auger 

hole, an uppermost 6-inch (15 cm) sample was 

taken, then a second sample from 6 inches to 1 

foot (15-30 cm) deep, and a third sample from 

1 to 2 feet (30-60 cm) deep. Where only two 

samples were taken, each is 1 foot (30 cm) 

long, one above the other. The samples from the 

0- to 1-foot depth include the A soil horizon and 

generally also the upper part of the B soil 

horizon. Samples from the 1- to 2-foot depth 

include most of the B soil horizon, and most 

samples also include some saprolite (C soil horizon), a residuum of rock weathered in place, 

which retains relicts of original texture. The 

lower samples in each hole inevitably receive 

some soil dropped from the upper part of the

hole, but contamination from this source is 

considered to be slight, owing to the small 

amount of added soil. Data in samples from 

depths of 0 to y% foot and 1/2 to 1 foot (Gair 

and Windolph, 1975, traverses 299; 301-309) 

appear to have no systematic variation; in subsequent traverses, the 0- to 1-foot zone was 

generally sampled by 1-foot samples. A comparison of data from 0- to 1-foot and 1- to 2- 

foot depths (fig. 2) indicates that there is little 

significant difference for most elements. However, copper, molybdenum1 , nickel, and fluorine 

have distinctly higher values at the 1- to 2-foot 

depth. Values for copper, particularly, may be 

in the background range in the shallower sample and distinctly higher in the deeper sample 

at any given site.

The geochemical highs for copper and molybdenum detected in the present study would not 

have been missed by sampling only to a 1-foot 

depth, but conceivably elsewhere in the Piedmont, copper and molybdenum values might 

exist in such a way that clusters of higher 

than average values occur in the 1- to 2-foot 

zone, but not in the 0- to 1-foot zone. Therefore it is advisable that geochemical (soil) explorations for copper and molybdenum in the 

Piedmont should sample to at least the 2-foot 

(60 cm) depth.

GEOCHEMICAL DATA

The locations of sampling traverses are 

shown with respect to principal geologic features, mineralized veins, and other major 

quartz veins on the map (fig. 1).

In general, on casual inspection only, it has 

not been possible to correlate closely the raw 

data in a geochemical profile with specific host 

rock, except for tungsten, which was correlated with mineralized veins in area A, and 

bismuth, copper, and molybdenum, which 

were correlated with a large quartz vein in area 

B (fig. 1). Commonly also, underlying diabase 

is readily recognized by high values of cobalt, 

nickel, and chromium occurring together in 

a sample.

CONTAMINATION

Potentially serious contamination of the soil 

in terms of trace-element content is likely be1 Measurable amounts of molybdenum found only along one 

of the traverses represented in figure 2.
TABLE 1. Examples of analytical data from, two soil-sample traverses (area A in figure 1)

For these and corresponding data in other traverses of areas A, B, and C, see Gair and Windolph (1975).

Traverses 290 and 303. Upper value for each element from 0 to 1 ft (0-0.3 m) depth; lower value from 1 to 2 ft (0.3-0.6 m) depth;

underlined numbers are at or above geochemical threshold determined for soil derived from granodiorite-tonalite. 

Type of analysis: Color., colorimetric; A.A., atomic absorption; S.Q.S., semiquantitative spectrographic; S.I., specific ion.

Element "^P.6 ?f analysis

Sample

HH GG FF EE DD CC BB AA Z Y X w v U T S R

Traverse 290 

View north

W

Cu 

Pb 

Zn 

Be 

Mo 

Co 

Ni 

Cr 

Sb 

F

We

 __.S.Q.S ____. 

__ .A.A __ __. 

__ .A.A _______ 

__ A.A ___ . 

__ S.Q.S __ . 

__ Color _ .

__ .S.Q.S __ . 

__ .S.Q.S ____. 

__ .S.Q.S __ . 

_ .Color _ .

_ __ .S.I ____ .

:St

N 

N 

10 

20 

15 

20 

20 

25 

7 

3 

N 

N 

5 

7 

7 

10 

20 

30 

1 

1 

480 

520

N 

N 

10 

20 

15 

20 

15 

25 

3 

3 

L 

N 

5 

5 

7 

10 

15 

20 

L 

1 

560 

720

L L 

L 50 

10 10 

20 20 

15 20 

20 20 

15 15 

20 20 

5 5 

3 5 

N N 

N N 

5 5 

5 5 

7 7 

10 20 

20 30 

30 30 

1 1 

1 2 

600 920 

560 1,080

L L L L 

50 50 N L 

10 15 10 10 

15 30 10 20 

10 20 20 20 

20 25 15 25 

15 15 10 20 

15 20 15 20 

10 10 5 7 

7 573 

N N N N 

N L N L 

5 555 

5 555 

7 757 

20 20 7 10 

30 30 20 30 

50 70 30 50 

0.5 1 1 1 

1 211 

640 560 560 580 

720 440 640 440

L L 

L 50 

10 10 

15 15 

10 15 

20 15 

15 10 

15 10 

20 15 

20 10 

N N 

N L 

5 5 

5 5 

7 5 

7 10 

30 20 

30 30 

1 1 

1 1 

400 580 

680 840

N 

L 

10 

15 

25 

20 

15 

15 

10 

7 

N 

N 

5 

5 

7 

20 

30 

30 

1

520 

720

L L 

L L 

10 20 

10 25 

15 20 

15 25 

20 20 

15 25 

10 20 

5 10 

N T 

N L 

5 5 

5 5 

7 7 

10 20 

30 50 

30 70 

1 1

800 1.000 

520 1,000

L L 

L L 

10 20 

20 95 

20 20 

20 20 

15 20 

20 25 

20 15 

5 7 

L N 

L N 

5 10 

5 10 

7 10 

20 30 

50 20. 

50 150 

1 1

500 460 

560 440

Vein quartz float 

Traces of tungsten mineralization

N N 

50 N 

10 10 

15 15 

20 20 

20 20 

15 20 

15 15 

10 7 

15 20 

N N 

N N 

10 20 

10 20 

7 5 

7 7 

50 50 

50 30 

2 1

1 2 

360 310 

360 380

T

Principal 

vein

cause of mining- and related activity at the 

Hamme deposit. Care was exercised to avoid 

some of the obvious pitfalls, but in sampling 

such an area, probably the best one can hope 

to do is to minimize the effects of contamination. No samples were taken from disturbed 

or filled ground other than ordinary fields 

plowed to depths of about 1 foot (30 cm). It 

was assumed initially that ordinary cultivation 

did not cause significant lateral transport of 

trace elements, and the data obtained seem to 

support this assumption. High tungsten values 

occur at or near the projection of known veins 

even over plowed ground. Some samples were 

taken where soil had been removed previously, 

exposing saprolite. Although such material 

does not correspond to the normal sample in 

the weathering profile, it should be free of contamination by foreign material and therefore 

probably differs from normal samples mainly 

in being somewhat less weathered. Such material probably corresponds closely to the lowermost 1-foot sample at most of the sample sites. 

This lowermost sample commonly is partly or 

entirely saprolite. Probably the best check for

the absence of serious contamination in the 

orientation survey is the occurrence of high 

metal values where one would expect them, in 

samples at and adjacent to mineralized veins, 

and the presence of lower (background) values 

elsewhere.

HIGH TRACE-ELEMENT VALUES

As here arbitrarily defined, a high value for 

a trace element falls in approximately the upper 

sixth of an array of sample values for the element. Frequency distributions for most elements are approximately lognormal, so the geometric mean is taken as a measure of central 

tendency (average), and the geochemical 

threshold for high values is taken as the product of the geometric mean and deviation (table 

2), following Bell (1973).

The array of values and the geochemical 

threshold discussed in this preliminary evaluation are based on the total group of soil samples 

derived from each major rock type granitic 

rock or phyllite and its included dikes and 

veins. Average values and geochemical thresholds differ somewhat in soil over different
TABLE 1. Examples of analytical data from two soil sample traverses (area A in figure 1) Continued

Symbols for analytical results: Measurable values given directly in parts per million; L, element detected, but less than limit of measurement; N, element not detected at stated limit of measurement.

Limit of measurement (only for Mo and W, having L or N amounts: Mo, 4; W, 50). 

Underlying rock is granitic or as noted.

Element Typ,e of 

analysis Q P 0 N M

Sample

L K J I H G F E D c B A

Traverse 290 Continued 

View north

W s.Q.S __ . 

Cu _ A.A __ _ .

Pb __ A.A ____ . 

Zn __ A.A __ __. 

Be __ S.Q.S __ . 

Mo - Color

Co __ S.Q.S __ . 

Ni __ S.Q.S __ 

Cr __ .S.Q.S __ 

Sb ..Color _

F __ .S.I _ _ _ _.

Element

50 

L 

20 

25 

55 

20 

25 

25 

7 

10 

. 17 

N 

20 

30 

10 

10 

50 

70 

. 2 

2 

. 520 

600

50 

70 

20 

45 

60 

40 

25 

30 

20 

10 

IT 

N 

20 

20 

10 

30 

100 

150 

3 

T 

640 

640

L 

50 

50 

30 

50 

25 

40 

20 

10 

7 

N 

N 

70 

50 

70 

50 

200 

150 

2 

2 

400 

520

L 

L 

25 

40 

45 

65 

30 

35 

5 

5 

N 

N 

70 

70 

50 

50 

150 

150 

2 

2 

520 

540

Projection 

Type of

£0 

L 

20 

45 

35 

30 

25 

25 

10 

5 

N 

N 

70 

50 

30 

IQ 

150 

150 

1 

1 

440 

560

L N N N N N N 

L N L N N N N 

20 20 25 10 10 10 10 

65 30 25 10 20 20 15 

30 30 35 15 20 15 20 

25 30 25 15 25 20 20 

20 25 25 30 30 30 30 

30 25 25 30 55 60 50 

5 10 3 1 1 13 

3 7 3 1 1.5 3 1.5 

N N N N N N N 

N N N N N N N 

30 30 50 30 30 30 50 

30 30 70 30 30 50, 30 

30 50 30 20 15 10 20 

70 50 50 15 15 30 10 

150 150 150 100 70 70 50 

500 150 150 70 70 50 30 

1 0.5 2 1' 1 11 

21211 21 

370 270 270 110 180 110 180 

540 320 360 110 250 320 280

N 

N 

5 

5 

15 

10 

20 

20 

1 

1 

N 

N 

15 

10 

5 

5 

30 

30 

1 

0. 

100 

100

N 

N 

20 

10 

20 

20 

55 

25 

2 

7 

N 

N 

30 

10 

20 

30 

50 

150 

2 

5 1 

220 

240

N 

N 

20 

25 

80 

30 

35 

25 

3 

3 

N 

N 

30 

30 

50 

50 

IQ 

150 

0.5 

2 

220 

240

N 

N 

25 

35 

25 

25 

30 

30 

3 

3 

N 

N 

50 

30 

70 

7Q 

200 

150 

1 

2 

260 

240

of diabase dike

Sample

analysis 

[Value in upper row of each

K J I H G F E 

element is the average of two reported analyses]

D c B

N 

N 

20 

10 

25 

20 

45 

30 

1.5 

1.5 

N 

N 

30

To

15 

10 

50 

50 

1 

1 

210 

140

East

A

Traverse 303 

View north

W __ _____ _ ___

Cu ___ ____ ___

Pb _____ _ __

Zn _ __ _ _ _ _ _

Be - __ _ _

Mo _____ __ _____

Co _______________

Ni ______ __ _____

Cr _____ _________

Sb ___ ____ _ _ __

F _ _

West

SQS

A.A

A A

A A

SQS

Color 

S.Q.S 

SQS

SQS

Color 

S.T

 

L L 50 L 110 125 

50 50 100 L 150 100 

17 12 12 22 35 27 

35 15 30 20 50 35 

25 15 12 30 65 35 

20 10 15 20 100 20 

45 22 25 40 25 32 

20 15 20 35 50 20 

10 10 10 3 17 35 

15 50 7 3 7 20 

N N L 4 N L 

L N 4 N N N 

56 7 20 8 7 

10 7 10 20 7 7 

10 20 30 30 50 70 

100 30 50 30 150 100 

20 17 20 17 30 40 

50 30 30 20 20 30 

32 2 34 2 

22 2 24 2 

590 470 860 1,720 1.08~0~ 1.080

1.000 920 1,240 1,760 960 1,080

L 

L, 

20 

25

17 

20 

25 

20 

3 

3 

L 

L 

10 

7 

30 

30 

50 

70 

2 

1 

470 

720

N 

N 

17 

20 

20 

20 

17 

30 

3 

3 

N 

L 

25 

10 

40 

30 

30 

30 

1 

2 

460 

480

N 

N 

25 

20 

22 

20 

37 

40 

3 

2 

N 

N 

15 

20 

40 

50 

30 

30 

3 

1 

540 

520

N 

N 

20 

25 

25 

25 

42 

45 

6 

2 

L 

L 

17 

20 

50 

50 

30 

30 

1 

1 

620 

840

A 

Projection 1 of principal vein

N 

N 

22 

35 

17 

25 

35 

45 

3 

3 

L 

L 

10 

10 

30 

70 

20 

30 

.5 

1 

560 

920

East

rocks; if the samples considered were restricted 

to local variants of the granite or phyllite or to 

their included dikes and veins where average 

values are markedly above or below the average 

for the entire unit sampled, threshold values 

would vary accordingly. Values that are high

relative to a selected group of surrounding 

values and so may be significant for mineral 

exploration may not be high compared with the 

total population. Therefore, the threshold 

values listed herein (table 2), which are based 

on the total sample population for a major
100 

ppm

/ /

100 

ppm

/

/ 100

ppm

/

S

50 

ppm

100 ppm 0

Cu Pb

100 ppm 0

TRAVERSE 289

100 ppm 0

Zn

100 ppm 0

Cu Pb

100 ppm 0

TRAVERSE 297

100 ppm 0

Zn

50 ppm

Be

100

ppm

/ 100

/ ppm

./

 /A*

/ 100

/ ppm

" / *

jf'

/ 50 1

/ ppm

' ' /

l£tf W9^f 

X» 9

/

/

/

$> :

50 ppm

Be

100 

ppm

/ 100 

' ppm

 /

/ "'":"

/ 100 

/ ppm

r^* 

/ 50 

/ ppm

/&-

 /

jTX

Cu

100 ppm 0 100 ppm 0

Pb

100 ppm 0

Zn

 1 occurrence

 2 occurrences

TRAVERSE 309

EXPLANATION

A 3 occurrences

4 or more occurrences

50 ppm

Be

FIGURE 2. Comparison of trace-element values (parts per million) at 0- to 1-foot (0-0.3

data tabulated in Gair

8
100 / 50 

ppm / ppm

^ ;

/ 100 

/ ppm

X* X*

' / 

x 

 * 

X

1000 

ppm . X

 X 'X. x--'

/ 

0 100 ppm 0 50 ppm 0 100 ppm 0 1000 ppm

Co Ni Cr

TRAVERSE 289

100 / 50 

ppm .' ppm x

 J* * ..'

/ 100 

/ ppm

.. /* A

X '

^:

F

^200

 /

 / ^ -??sn /^^

- 1000 X

ppm S 

/» 

>^""^

0 100 ppm 0 50 ppm 0 100 ppm 0 1000 1500 

Co Ni Cr F PPm PPm

TRAVERSE 297

100 / 50 

ppm / ppm

jf*

/ 100 

/ PPm

X'X

/tf J :

y~

*/

x- :*

1000 

ppm

150

1800 s

/ t 1760

 /-'" -T

X;s.. ' '' '«

X i

0 100 ppm 0 50 ppm 0 100 ppm 0 1000 ppm 

Co Ni Cr F

TRAVERSE 309

50 / 

ppm / i

 / £

X Q

s*fa 

0 50 ppm

o 

o

TRAVERSE 309 1-TO 2-FOOT DEPTH

m) and 1- to 2-foot (0.3-0.6 m) depths. See figure 1 for traverse locations. Analytical 

and Windolph (1975).
TABLE 2. Trace-element statistics mean values, deviation, and arbitrary

[Type of analysis shown in parentheses; see

W (S.Q.S.)

Lower

ft

Upper 

ft

Cu (A. A.)

Lower 

ft

Upper

ft

Pb (A. A.)

Lower

ft

Upper 

ft

Zn (A. A.)

Lower

ft

Upper 

ft

Be (S.Q.S.)

Lower

ft

Upper 

ft

Granitic rock

Total samples _ _ _ _ _

Censored values (N or L) 1 __ 

Geometric mean 3 (parts per 

million) __ _

Geometric deviation 3 (parts 

per million)

Geochemical threshold 4 (parts 

per million) 5

405 

320

5 50

405 

338

5 50

405 

0

20.77 

1.84 

38

405 

1

14.92 

1.85 

28

405 

6

19.17 

1.78 

34

405

4

18.39 

1.91 

35

405 

0

22.56 

1.70 

38

405 

0

21.23 

1.75 

37

405 

16

4.17 

2.51 

10

405

14

5.73 

2.50 

14

Phyllite

Total samples _ _

Censored values (N or L) 1 ____ 

Geometric mean 3 (parts per 

million) _ _

Geometric deviation 3 (parts per 

million ) _

Geochemical threshold * (parts 

per million

381 

361

5 50

383 

373

5 50

381 

1

24.73 

2.36 

58

383 

3

16.75 

2.29 

38

381 

8

12.04 

1.57 

19

383 

10

10.64 

1.65 

18

381 

0

21.02 

1.84 

39

383 

0

17.60 

1.77 

8 31

381 

169

2.18 

2.05 

9 5

383 

169

2.52

2.24 

9 5

1 Element not detected at stated limit of measurement (N), OT element detected but is below limit of measurement (L).

2 87 samples with no values reported in lower foot, and 88 samples with no values reported in upper foot; computations basel on 308 

values in lower foot and 303 values in uoper foot.

3 No corrections made for bias that would result from using censored values. Geometric mean and deviation based on reported values 

only. Reported values eaual total samples less censored values, or as otherwise determined for Sb and explained in footnotes 2 and T. 

* Geochemical threshold computed as geometric mean X geometric deviation, rounded to nearest whole number.

rock type, do not preclude lower or higher 

thresholds in limited areas. Average values of 

selected elements in segments of the area sampled that represent essentially only the included dikes or veins commonly are above the 

threshold for the major rock unit as a whole, 

so the defined threshold, although arbitrary, is 

useful for identifying such different source 

rocks within the granite and phyllite.

The geochemical thresholds selected for the 

various elements are reasonably consistent with 

the results of the orientation survey; good correlation between the threshold (and higher) 

values and known dikes and veins provides empirical justification for the chosen levels. Significantly higher threshold levels would provide 

fewer "high" values and would result accordingly in a poor correlation of "high" values 

with known dikes and mineral veins; lower 

threshold levels than those chosen, on the other 

hand, would result in too wide a distribution of 

"high" values to permit their correlation with 

the limited zones containing dikes or mineralized veins. At the chosen level (approximately 

the upper one-sixth of values for an element), 

there is a high degree of correlation of certain 

elements above known mineralized veins and of

other elements above diabase. Thus, in soil over 

mineralized veins, or in dispersion zones commonly within 150 feet of veins, tungsten, copper, lead, beryllium, antimony, and fluorine 

commonly are at or above threshold values, and 

over diabase, copper, zinc, cobalt, nickel, and 

chromium commonly are at or above threshold 

values. Clusters of high values of these elements 

also occur at sample sites where veins or diabase are not known. Such clusters may have a 

variety of causes, the most likely being the 

presence of veins or dikes that have not been 

recognized, concentrations of vein or dike float 

in the soil, and scavenging or concentration of 

the trace elements by oxides of iron or manganese. Making distinctions between such spurious trace-element concentrations and the significant concentrations is one of the most vexing problems of geochemical exploration, but 

it may be aided by careful field observations, 

by noting corresponding changes in the traceelement and iron-manganese content of samples, by measurements of clustering as described below, and by various statistical manipulations of data.

Average values and threshold values vary 

both with underlying rock type and with depth

10
geochemical threshold in soil samples from granitic rock and phyllite areas

tables 1 and 3 for explanation of abbreviations]

Mo (Color.)

Lower

ft

Upper 

ft

Co (S

Lower

ft

.Q.S.)

Upper 

ft

Ni(S.Q.S.) Cr (S.Q.S.) Sb ( Color.)

Lower

ft

Upper Lower 

ft ft

Upper Lower 

ft ft

Upper 

ft

Bi (S.Q.S.)

Lower 

ft

Upper 

ft

F (S.I.)

Lower 

ft

Upper 

ft

Granitic rock Continued

405

364

5 4

405 

391

5 4

405 

1

11.59 

1.89 

22

405 

0

10.31 

1.93 

20

405 

1

17.63 

2.15 

38

405 405 

1 0

11.90 43.36 

2.01 2.05 

24 87

405 405 

0 2 10

35.34 1.37 

2.01 2.32 

6 71 3

405 2 14

1.41 

2.04 

3

405 

403

5 10

405 

405

3 10

405

20 

402 

2.71 

1,090

405

43 

362 

2.45 

890

Phyllite Continued

381

290

5 4

383

297

5 4

381 

0

10.67 

1.87 

20

383 

3

9.64 

1.87 

18

381

0

15.05 

1.86 

28

383 381 

1 1

9.61 47.92 

2.57 1.99 

25 95

383 381 

1 7 1

39.83 1.10 

1.92 1.84 

77 2

383 7 10

1.06 

1.92 

2

381 

336

5 10

383 

357

5 10

381 

80

207 

3.10 

640

383 

109

195 

2.94 

570

5 Lower limit of sensitivity used instead of computed geochemical threshold because of high number of censored values.

6 70 ppm used as threshold. 

7 241 samples not analyzed for Sb in lower foot, and 242 samples not analyzed in upper foot; analyzed population is 139 samples (reported 

values) in lower foot and 131 samples in upper foot.

8 30 ppm used as threshold.

n Threshold value arbitrarily selected to separate approximately lower five-sixths of values from upper one-sixth of values. Values 

below threshold include 169 censored values.

in the soil profile. For example, in soil from 

granitic rock, the threshold for copper is 28 

ppm at a depth of 0-1 foot and 38 ppm at a 

depth of 1-2 feet; in soil from phyllite, the 

threshold for copper is 38 ppm at 0-1 foot and 

58 ppm at 1-2 feet (table 2). The higher 

threshold values in soil from phyllite are believed to correspond to a higher average background copper content in the phyllite than in 

the granitic rock, although data on rock compositions have not been obtained for verification.

The thresholds for high values of molybdenum and tungsten are not readily established 

even by arbitrary manipulation of analytical 

data because a large proportion of samples has 

censored values below the limits of sensitivity 

of the analytical method (4 ppm for molybdenum and 50 ppm for tungsten). The sporadically distributed measurable tungsten occurs 

principally if not solely in areas containing 

mineralized quartz veins and vein quartz float. 

The background content of tungsten in the 

granitic and phyllitic country rock is clearly too 

low to concentrate measurable amounts in the 

soil. Similarly, the sporadically distributed

measurable molybdenum probably represents 

mineralized (molybdenum-bearing) rock, 

whereas the background content of molybdenum in the country rocks is too low to produce measurable amounts in overlying soil. Because the lowest measurable value of molybdenum or tungsten represents mineralized rock, 

and in effect occurs somewhere within the outer 

edge of the corresponding geochemical high, the 

real threshold value is probably less than the 

lower limit of measurement. However, for practical purposes, 4 ppm molybdenum and 50 ppm 

tungsten are taken, as threshold values.

The values in table 2 for beryllium, cobalt, 

chromium, copper, nickel, lead, antimony, zinc, 

and fluorine are derived from a large proportion if not all of the samples (in contrast to 

values for molybdenum and tungsten), so are 

used to compute thresholds. For each trace 

element considered, there is a range of threshold values; values differ for samples taken 

over granitic rock and phyllite, and for samples 

from the 0- to 1-foot and 1- to 2-foot depths. 

Such threshold values are (except for copper, 

already given) : for beryllium, 10-14 ppm (over 

granitic rock) ; for cobalt, 18-22 ppm; for

11
chromium, 71-95 ppm; for nickel, 24-38 ppm; 

for lead, 18-35 ppm; for antimony, 2-3 ppm; 

for zinc, 31-39 ppm; and for fluorine, 570-1,090 

ppm. Nearly half the beryllium analyses in soil 

from phyllite result in censored values. So, to 

utilize the large number of both numerical and 

censored values in computing a threshold for 

such beryllium, the 169 censored values are 

considered part of the total array, and a division is made between the lower five-sixths 

and the upper one-sixth of all values. If this 

procedure is used for populations that have no 

censored values, the results are similar to the 

product of the geometric mean and deviation.

Isolated high values may be part of a background population, so only high values that are 

spatially clustered or alined are considered significant. The determination of significant degrees and patterns of clustering of high traceelement values is generally hampered by gaps 

in the spatial distribution of data and requires 

careful judgement. Widely spaced reconnaissance traverses (such as those in area C in 

fig. 1) generally will require followup sampling 

to determine the lateral extent of any data 

clusters that may be detected only in profile 

along a single traverse.

The sample traverses provide a simple means 

of measuring data clustering in a profile (table 

3 for selected traverses in area A). Clustering 

of high values of the eight vein-affiliated elements (tungsten, copper, lead, zinc, beryllium, 

molybdenum, antimony, and fluorine) and of the 

five diabase-affiliated elements (copper, zinc, 

cobalt, nickel, and chromium) commonly is 

greatest immediately above or adjacent to 

known mineralized veins or diabase dikes, although in places greater clustering is caused 

by float than by source veins or dikes. The index of clustering in table 3 is a measure of the 

number of high values of these elements at a 

sample site (adding together high values for 

the 0- to 1-foot and 1- to 2-foot depths) plus the 

number of contiguous high values. The clustering indexes for the vein-affiliated and diabaseaffiliated groups are equated according to the 

number of elements in each group. An index 

of 1 for the vein-affiliated elements, for example, might be caused by high values for all eight 

elements in each of the two samples taken at a 

single sample site, or for only one of the elements, present in each of the two samples taken 

at eight contiguous sample sites. Generally an 

index as high as 1 represents some combination 

of high values at a sample site plus contiguous 

high values.

Because of varying dispersion and dilution 

of the affiliated elements, there is no absolute 

index of clustering that identifies diabase or 

mineralized vein quartz. Nevertheless, known 

mineralized vein material is generally marked 

by clustering indexes in the range, 0.5 to 2.0, 

and diabase, by indexes of 0.6 to 5.0. Clustering 

indexes of vein-affiliated elements higher than 

1 are a strong indicator of mineralization. On 

the other hand, high clustering indexes for diabase-affiliated elements are found over some 

zones in the phyllite where no diabase is known. 

These concentrations probably represent unmapped diabase, or a basaltic precursor in those 

parts of the phyllite.

The spatial distribution of high values and 

high indexes of clustering and the dimensions of 

areas containing clusters of high values will 

determine how much significance is to be attached to the trace-element data for mineral 

exploration. The high bismuth, copper, and 

molybdenum values described below in area B 

and the wide zone of high tungsten values described below in area C are the only sizable 

groups of high values found that are not related to heretofore-known mineralized veins. 

The high bismuth, copper, and molybdenum 

values apparently correspond to an area of massive white vein quartz outcrop, which contains 

little visible evidence of mineralization.

DISTRIBUTION OF HIGH TUNGSTEN 

VALUES

Generally the measurable tungsten values are 

found directly above and within 100 to 200 feet 

downslope from known mineralized veins. 

However, tungsten values also occur in isolated 

clusters at distances of several hundred feet 

downslope from known veins. Measurable tungsten values also correspond to some areas of 

huebnerite-bearing vein quartz float not directly related to known veins (for example, see 

Gair and Windolph, 1975, traverse 294, samples D, E, F, G, H, I; traverse 306, samples L, 

N, O). The highest tungsten values in a cluster 

are as commonly found downslope from a vein

12
as directly above it. The probable explanation 

for such irregular distribution is that huebnerite is resistant to chemical weathering and 

contributes to tungsten anomalies mainly as 

particles of the mineral, which however well 

comminuted by mechanical weathering, is irregularly distributed in the soil adjacent to 

veins.

AREA OF HIGH BISMUTH, COPPER, AND 

MOLYBDENUM VALUES

A major assemblage of high bismuth, copper, 

and molybdenum values occurs in soil on a 

prominent north-trending ridge (fig. 1, area B) 

8,000 to 9,000 feet (2.5-2.8 km) northeast of 

the southwest corner of the Tungsten TVsminute quadrangle and about 2,000 feet (600 

m) west of the principal mineralized veins. The 

ridge bounds the west side of the new tailings 

pond constructed by Ranchers Exploration and 

Development Corp. in conjunction with the reopening of the tungsten mine in 1970. The 

ridge is underlain by north-trending massive 

white vein quartz which cuts phyllite of the 

Carolina slate belt. Most of the quartz is barren in appearance, but some contains weathered-out pits and remnants of limonitic pseudomorphs evidently representing a metallic mineral or minerals. A few randomly collected 

hand samples of the vein quartz contain values 

of a few hundred to 1,000 ppm bismuth, copper, 

and molybdenum.

Five east-west sampling traverses (figs. 1,3; 

Gair and Windolph, 1975, traverses 310, 317- 

320) have been made across the ridge without 

entirely bracketing and delimiting the area of 

high bismuth, copper, and molybdenum values 

which is at least 1,200 feet (365 m) long and 

400-800 feet (120-240 m) wide and which evidently extends north, south, and perhaps west 

beyond the sampled area. Isopleth maps of 

copper and molybdenum values (copper, >20 

ppm and molybdenum, >15 ppm; fig. 3A, B) 

show the crest of the anomalies for these elements angling slightly across the crest of the 

ridge. High bismuth values of 10-200 ppm are 

more scattered (fig. 3C) than the copper and 

molybdenum values but commonly occur in 

clusters of three to five contiguous samples; in 

traverse 317, they are present in 12 contiguous

samples taken across a zone 550 feet (168 m) 

wide. In contrast, bismuth was not detected in 

most of the samples taken in areas A and C, 

except in traverses 308 and 309, as noted below. The contiguous high values for copper and 

molybdenum at all or nearly all sample sites 

are largely responsible for the fairly high 

clustering indexes at every site. For example, 

indexes in traverse 319 range from 2 to 3.25. 

About three-fourths of a mile (1.2 km) to the 

south on an extension of the ridge, traverses

308 and 309 (fig. 1; Gair and Windolph, 1975) 

also reveal contiguous molybdenum values 

above background values, and background copper values (especially at the 1- to 2-foot depth) 

rather persistently above mean values. Also, 

traverses 308 and 309 are the only others in the 

survey, besides those in area B, that contain 

measurable values of bismuth in contiguous 

samples. Clustering indexes in all of traverse

309 are high 2.1 to 6.7 the greatest clustering being where the principal Hamme vein 

intersects the ridge. The entire ridge between 

traverses 309 and 310 may be a bismuth-coppermolybdenum-zone.

BORDER ZONE OF PLUTON SOUTH OF 

HAMME MINE AREA

Geochemical soil samples have been collected 

across the border zone of the granodioritetonalite pluton in area C, along the projection of 

the principal vein system of the Hamme mine, 

for 1 to 3 miles (1.6-4.8 km) south of the south 

end of area A (see fig. 1). Quartz veins, abundant vein quartz float, and tungsten mineralization are found in places in this area (Espenshade, 1947, pi. 1). As the south end of the 

principal vein system in the mine is within the 

phyllite, and known quartz veins to the south 

occur in a wider zone in the phyllite than in the 

granodiorite, the traverses have been extended 

farther across the phyllite than the granodiorite.

Clusters of high tungsten values occur near 

the west end of traverse 311 and the middle and 

east end of traverse 313 (Gair and Windolph, 

1975). The zone of high values at the east end 

of traverse 313 is about 300 feet (95 m) across 

 which compared with zones of contiguous 

high tungsten values in the vicinity of the mine

13
TABLE 3. Clustering indexes in selected traverses of area A

Traverse locations shown in figure 1; underlying rock is as indicated or is granitic. Analytical data for traverses 290 and 303 in table 1; data 

(1975).

Vein-affil., eight trace elements commonly affiliated with mineralized veins; diab-affil., five trace elements commonly with diabase. View north fo

is viewed to the east.

Clustering index (CI) measured by number (N) of values that are at or above threshold at a given sample site, at both sample depths, 0-1 

the vein-affiliated and diabase-affiliated values) plus the number of values of the same elements at contiguous sampling sites along a traverse. 

for _ diabase-affiliated elements, CI=N/(5X2). In order to set CI = 1 when there are high values for all the affiliated elements at a singl

affiliated and diabase-affiliated elements, respectively, is multiplied by 2 to provide for the two samples taken at each site. High values for Cu 

and diabase-affiliated dusters. Index values rounded to the nearest tenth.

Sample site __-- ABCDEFGH I JKLMNOPQ RST 

.Vein-affil _____ 0.2' 0.1 0.3 0.4 0.3 0.4 0.2 0.2 0.1 0.5 0-7 0.5 0.4 0.4 0.4 0 0.6 0.4 0.1 O2 

Diab-affil _____ 1.3 | 1.3 1.8 2.1 2.0 1.8 1.6 .3 .1 .1 .1 .3 .4 .3 .1 0 .5 .4 .4 .5 

Phyllite | Granitic rock

Traverse 289 ..

Sample site - HH GG FF EE DD CC BB

Traverse 290

Traverse 291

--Vein-affil __ _ ___ 

Diab-affil -.. _ _

Sample site - _

-_Vein-affil ____ __ 

Diab-affil -- _____

0 

0

A

0.1 

0

0 0 

0 0

B

0.1 

.2

0.2 0.2 0.2 0 

0000

C D E F

0 0.4 0.4 0.4 

0 .2 0 0

AA Z

0 0.2 

0 0 

ied vein 

float

G H

0.2 0 

0 0

Y X

0.3 0 

0 0

I J

0 0 

0 .5

W

0 

0

K

0.1

9

V

0.3 

0

L

0 

1

U T

0.2 0.2 

0 .2

M N

0.7 1.0 

0 .9 .9

SRQPONMLKJ I H

0.3 0.2 0.7 1.1 0.5 0.5 0.5 0.1 0 0.1 0 0.1 

0 1.8 1.4 3.0 5.3 5.3 5.3 5.3 5.2 5.2 3.3 3.5 

Vein

O PQR STUVWXYZA

1.1 1.0 0.3 0 0.2 0.3 0.2 0.1 0.2 0.8 0.3 0

0 .5 .4 .4 .4 0 0 0 .2 .4 .1 

Mineralized 

vein

Sample site __ A A Z W UTS R Q O N M K IHG E D

Traverse 292 -.Vein-affil .. 

Diab-affil _-_

0.6 0.5 0.2 0.3 0.1 0.2 0.1 0 0 0 0 0.1 0 0.2 0.2 0.2 0 0 0 0 0 0 0 0.1 0.3 

. 0 .3 0 .1 .1 0 0 0 .1 1.5 1.5 2.4 2.4 2.8 3.0 3.2 2.8 2.8 2.3 1.6 1.9 4.3 4.3 4.4 2.7 

Principal Diabase 

vein

Traverse 294

Traverse 295

Sample site - ___

--Vein-affil __ ___

Sample site 

 Vein-affil _______

Diab-affil _ ______

CCBBAAZYXWVU T SRQPO

0.3 0.2 0 0.1 0.1 0.2 0.1 0.2 .03 0.4 0.4 0.4 0.4 0 0.1 

0 000 .10000 .1 .3 .3 .2 0 .2 : :

float vein

DDCCBBAAZYXWVUTS RQP

0.6 0.4 0 t;4 1.1 0.7 0.4 0.1 0 00 0 0.2 0.1 0.4 

.2 .2 0 00 00 .1 .1 0 .6 .3 .8 .4 .5

N

0 

0

O

0 

.5

M

0.1 

.6

N M

0 0 

0 0

L K

0.1 0.1 

.6 .5

L K J

000 

000

J

0.4 

.2

I

0 

0

I H G

0.2 0.2 0

.4 0 .7

HGF

FED

0 0 

2.3 2.

E D

00 0 0 0.1 

0 .6 .9 .9 1.0

.3 

C 

0.

.

Traverse 296

Traverse 297

Traverse 299

Sample site 

-_Vein-affil _.-__ _ 

Diab-affil - ______

Sample site - _ _

-_Vein-affil _ --_ _

Sample site ___--

_-Vein-affil __ ___

ABC

0.7 0.9 0.7 

3.3 3.2 3.2

OO NN MM

1.5 1:7 1.7 

0 .4 .4 

Pjrin«ipal 

vein

G

1.9 

.2

F E

1.6 1.5 

0 0 

Principal 

Vein

D E F

1.0 0.7 0.5 

3.3 2.9 2.8 

1 Phyllite

LL

1.3 

.3

D

1.1 

0

KK

0.7 

.1

C

1.0 

.1

JJ

0.4 

0

B

0.9 

.2

GHI JKLMNOP Q R S

0.4 1 0 0.2 0.3 0.4 0.1 0.1 0.2 0.1 0.2 0.3 0.3 0.1 

2.2| 0 0 .20 0 0 0 0 .10 0 0 

| Granitic rock

II HH GG FF EE DD CC BB AA Z

0.1 0.6 0.1 0.1 0 0 0 0.1 0.1 0.1 

.2 .5 .2 0 0 0 0 0 .20

A

0.9 

.1

YXWVUT SRQPONM

0 0 0 00 0 0.1 0 0.2 0 0 0.1 0.

0 0 0 0 .1 .2 0 .1 .2 0 00 0 

Vein quartz 

float 
TABLE 3. Clusterng indexes in selected traverses of area A Continued

Traverse 301

Traverse 302

Traverse 303

Sample site 

.-Vein-affil - __ _. 

Diab-affil ........Sample site ... 

..Vein-affil ....... 

Diab-affil ____ .

Sample site _ 

..Vein-affil _ . _ 

Diab-affil _ _____ F E 0.1 0.8 0 .1 Principal vein J0.4 .1K0.4 .2 I 0.2 0 J0.3 0 D0.8 .1H C0.6 0G B0.5 0 F 0.3 B.G 0.7 0 0 .1 Principal Vein I0.4 1.0 H0.5 1.1 GLI 1.2 A0.7 0EDO 0 0.1 0 0 .1 0 F E 0.7 0 1.1 .9 B A 0 0 0 .1 D C B 0.1 0.2 0.1 1.2 1.6 1.6 A0.1 1.4

Projection of 

principal vein

Sample site _.___

Traverse 305 ..Vein-affil .... _ 

Diab-affil ________ 1.6 1.6 1.4 0.9 1.4 1.7 1.5 .9 0.9 0.9 0.4 .5 .3 .6

Mineralized vein 

quartz float

Traverse 307

Sample site .....

..Vein-affil _______ Diab-affil ________ Q0 .3 P O N M 0 0.2 0.1 0.1 000 .1 L K J 0.1 0.2 0.4 0 0 .2 I H 2.1 2.1 0 ,2 G F 1.7 2.8 0 .1 E2.7 ?, D2.8 1 C2.6a B2.6 0 A1.5 .2

PhyJlite Granitic rock Principal

________ Sample site ___ ABCDEFGHIJ KLMNOPQRST UVWXYZAABBCCDDEE Traverse 309 --Vein-affil -.._ 3.4 3.2 3.1 3.8 3.4 3.6 3.6 3.7 3.6 3.7 2.8 2.8 2.1 3.4 3.4 3.4 3.5 -3.9 5.3 5.1 4.4 C4 6.7 6.4 6.0 5.9 6.4 6.7 6.7 6.11 4.6 

Diab-affil .____ .2 .2 .2 .3 .1 .1 0 .3 .2 .3 .3 0 .4 .3 .3 .3 .3 .1 .2 0 0 : <«3 :: ,4 .2 .3 0 .10 .1 0

Phyllite :/P*ia«il>al Phyllite . Granitic vein Rock

1 High clustering of diabase-affiliated elements over nominal phyllite suggests that phyllite there may be metabasalt.
70

EXPLANATION 

Sample location, value in ppm

. _ _ Isopleth, dashed where 

approximately located

Areas with copper values of: 

>200 ppm

100 to 200 ppm 

50 to 100 ppm 

20 to 50 ppm

200

I

400 FEET

50 100 METRES

FIGURE 3. Isopleth maps of geochemical data showing areas of high bismuth, copper, and molybdenum values. 

A, Copper values at depth of 1 to 2 feet; analytical method: atomic absorption. B, Molybdenum values at 

depth of 1 to 2 feet; analytical method: colorimetric. C, Bismuth values at depth of 1 to 2 feet; analytical 

method: semiquantitative spectrographic.

16
EXPLANATION

100 " Sample location, value in ppm 

 Isopleth

N

Areas with molybdenum 

values of:

TOJg 70 / TRAVERSE 317

20'.'-:-15 \ TRAVERSE 318 * "- - .

TRAVERSE 319

TRAVERSE 320

B 200 400 FEET

I I

50 100 METRES

FIGURE 3. Continued

17
EXPLANATION

o/\ 

v Sample location, value in ppm

N, not detected at the limit of 

measurement

. _ _ Isopleth, dashed where 

approximately located

Areas with bismuth values of: 

>50 ppm

fllNflljIjf TRAVERSE 317

|pi<^;;N:i ||;if | TRAVERSE 319

!m TRAVERSE 320

50 100 METRES

FIGURE 3. Continued

18
in area A, is unusually wide (providing the 

suggested mineralization follows approximately 

the regional trend here and is crossed at a large 

angle by the traverse). Despite the presence of 

quartz veins south of traverse 313, there is no 

indication in the soil samples that tungsten 

mineralization reaches south of that traverse. 

On some of the other traverses in area C, there 

are small clusters of high values for copper, 

lead, zinc, or beryllium, which mainly appear 

not to be associated spatially with one another 

and probably are not significant.

CONCLUSIONS

The orientation survey shows that tungsten 

mineralization of ore grade (about half a percent or more tungsten) produces spectrographically measurable tungsten values in soil 

where veins reach the land surface or contribute noticeable float to the soil. Higher tungsten values, however, commonly are only a few 

times higher than the smallest amounts of tungsten that can be measured in samples by the 

spectrographic method used. Soil samples from 

areas of weakly mineralized vein quartz, well 

below ore grade, are not likely to contain measurable amounts of tungsten.

The area of high bismuth-copper-molybdenum values is interpreted as a reflection of 

more abundant minerals containing these elements in the vein or veins underlying that area 

than in the tungsten-bearing veins to the east.

Also, the magnitude and continuity of the high 

values of copper and molybdenum probably express the greater solubility of the copper and 

molybdenum minerals than huebnerite and the 

easier dispersal of copper and molybdenum than 

of tungsten by chemical weathering. The presence of a zone relatively rich in bismuth, copper, and molybdenum adjacent to the zone of 

tungsten veins might be caused by temperature 

zoning of original ore fluids.

REFERENCES CITED

Bell, Henry III, 1973, Some results of geochemical sampling in McCormick County, South Carolina: U.S. 

Geol. Survey Bull. 1376, 22 p.

Butler, J. R. and Ragland, P. C., 1969, A petrochemical 

survey of plutonic intrusions in the Piedmont, 

southeastern Appalachians, U.S.A: Contr. Mineralogy and Petrology, v. 24, no. 2, p. 164-190.

Espenshade, G. H., 1947, Tungsten deposits of Vance 

County, North Carolina, and Mecklenburg County, 

Virginia: U.S. Geol. Survey Bull. 948-A, 17 p.

Gair, J. E., and Windolph, J. F., Jr., 1975, Geochemical 

soil sampling traverses, Hamme tungsten district, 

North Carolina. Traverses 289-299; 301-323. U.S. 

Geol. Survey, open-file report, 3 p., 32 tables.

Hawkes, H. E., and Webb, J. S., 1962, Geochemistry in 

mineral exploration: New York Harper and Row, 

415 p.

Miesch, A. T., 1967, Methods of computation for estimating geochemical abundance: U.S. Geol. Survey 

Prof. Paper 574-B, 15 p.

Parker, J. M. 3d, 1963, Geologic setting of the Hamme 

tungsten district, North Carolina and Virginia: 

U.S Geol. Survey Bull. 1122-G, 69 p.

19

* U.S. GOVERNMENT PRINTING OFFICE: 1975 O 585 471 /62