Geochemical Studies 

in the Southwestern 

Wisconsin Zinc-Lead 

Area

GEOLOGICAL SURVEY BULLETIN 1000-E

<<

A CONTRIBUTION TO GEOCHEMICAL PROSPECTING

FOR MINERALS

\ r _____________

GEOCHEMICAL STUDIES IN THE SOUTHWESTERN 

WISCONSIN ZINC-LEAD AREA

By VANCE C. KENNEDY

ABSTRACT

Samples of natural water, soils, and rocks were collected in the southwestern 

Wisconsin zinc-lead area and analyzed for lead, zinc, and "total heavy metals" 

(undifferentiated lead, zinc, and copper). The purpose of the study was to 

determine whether known geochemical techniques might be of use in searching 

for ores in this mining district.

Anomalously high concentrations of lead and zinc were found in unweathered 

rock and in undisturbed residuum in the vicinity of known deposits of lead and 

zinc. In addition, streams draining areas known to contain lead and zinc minerals were found to contain unusually high quantities of heavy metals (mainly 

zinc) in solution.

The data indicate that geochemical prospecting techniques should be of value 

in the search for ore in the southwestern Wisconsin zinc-lead area.

INTRODUCTION

This report describes the work done and the results obtained during 

a study of the distribution of zinc and lead in soils, rocks, and natural 

waters of the southwestern Wisconsin zinc-lead area.

The study was begun on the recommendation of A. V. Heyl, Jr., 

of the U. S. Geological Survey who suggested that an investigation 

be made of the applicability of geochemical prospecting techniques in 

southwestern Wisconsin. Field work begun in 1947 by Lyman C. 

Huff was continued under the direction of the writer during the 

following three summers.

The data of Huff's preliminary investigation showed pronounced 

variations in the quantity of heavy metals (undifferentiated zinc, 

lead, and copper) in solution in spring, stream, and mine waters in the 

vicinity of Potosi, Wis. The study of waters near Potosi was continued during the summer of 1948 and was completed by the writer 

in the spring of 1950.

Sampling of soils and rocks was begun by the writer in 1948 and 

continued into 1950. This work included a study of the loess in some

187
188 CONTRIBUTIONS TO GEOCHEMICAL PROSPECTING FOR MINERALS

parts of the mining district, and of the distribution of metals in soil, 

rock, and ground water adjacent to known ore deposits.

In the course of these studies, the writer received help from individuals, employees of several mining companies, and from members of both the U. S. Geological Survey and U. S. Bureau of Mines. 

Robert R. Reynolds and Harold B. Ewoldt of Calumet arid Hecla 

Consolidated Copper Company, O. E. Dewitt of the Vinegar Hill 

Zinc Company, and William Singer of the Dodgeville Mining Company all supplied information. Will Andrews, owner of the property 

at Crow Branch, kindly gave permission for the detailed work done 

at Crow Branch and supplied information about past mining activity there. The Wisconsin Institute of Technology provided laboratory space and some laboratory equipment. A. V. Heyl, Jr., 

E. J. Lyons, and A. F. Agnew of the U. S. Geological Survey supplied information concerning the local geology and made valuable 

suggestions regarding the conduct of the work. John W. Allingham, 

also of the U. S. Geological Survey, collected and identified some of 

the sample rock cuttings from churn-drill holes. Wesley A. Grosh, 

Bureau of Mines engineer, supplied information regarding mineralization at both the Champion and Crawford properties, and assisted 

in the collection of samples at the Crawford property.

John F. Mink in 1949 and Victor J. Kling in 1950 were field assistants. Harold Bloom and H. E. Crowe made the quantitative analyses, and H. E. Crowe, A. P. Marranzino, J. H. McCarthy, and J. P. 

Schuch made most of the rapid semiquantitative analyses recorded 

here.

PURPOSE OF INVESTIGATION

Geochemical methods of prospecting for minerals depend on the

existence of unusual quantities of certain elements in material either 

genetically related to or derived from hidden ore deposits. If the 

distribution of some element forms a diagnostic pattern either in the

unweathered bedrock or in the various types of weathering products,

then the systematic collection and chemical analysis of large numbers

of samples may help in selecting sites for intensive exploration.

Chemical dispersion patterns indicative of mineral deposits, commonly known as geochemical anomalies or halos, fall naturally into

two groups: primary and secondary, A primary anomaly includes

all tile effects of dispersion of elements into the rocks surrounding or

overlying the mineral deposit, presumably by the same mineralizing

solutions that were responsible for ore deposition. It is a bedrock

feature, unrelated to the present erosion surface. The primary anomaly frequently forms a pattern surrounding the ore which, in crosssection, may resemble a halo. Hence, it has become a common prao-
; ' :STTJDIES' IN SOUTHWESTERN WISCONSIN ZINC-LEAD AREA'' 189

tice to refer to the pattern in the rock enclosing an ore deposit and 

containing an anomalous concentration of elements related to the 

deposition of the ores as a halo even though it may have a very 

irregular form. Secondary anomalies are the distribution patterns 

of elements resulting from the weathering either of the ore.body itself 

or of its associated primary halo. For a discussion of the principles 

and application of geochjemical prospecting methods see Hawkes 

(1950, p. 537-555) and Harbaugh (1953).

The effectiveness of geochemical prospecting methods in a given 

district depends on a number of factors, some of which can be determined in advance but most of which must be established by preliminary field experiments in the vicinity of known deposits.

One prerequisite is, of course, the availability of techniques of chemical analysis that provide adequate sensitivity, accuracy, speed, and 

economy. Chemical procedures suitable for many geochemical prospecting problems have been developed and described by Lakin, Almond, and Ward (1952); some of these were used in obtaining the 

data for the present report.

The question of what kinds of geochemical anomalies are associated 

with the ore deposits of the southwestern Wisconsin area, and whether 

a systematic search for these anomalies would be helpful in exploration can be answered only by field work. The purpose of the present 

investigation was to establish by experimental sampling in the vicinity 

of known deposits the characteristics of any geochemical anomalies 

related to known deposits, the most suitable sampling techniques for 

detecting and mapping these anomalies, and the kinds of anomalies 

that are likely to be the most useful in prospecting for new deposits.

TOPOGRAPHY AND GEOLOGY

The southwestern Wisconsin mining area lies, mostly, in the Driftless Area of midwestern United States (fig. 24). The relief is of the 

order of 100 to 300 feet, with the greatest relief usually being along 

the Mississippi Eiver. In general, the topography may be classified 

as mature.

BEDROCK GEOLOGY

' The strata consist principally of limestone and cherty dolomite of 

Ordoviciaii age, with some shale and sandstone (fig. 25). They lie 

nearly horizontal except for a regional dip to the south of about 18 

feet to the mile (Heyl, 1950, p. 14) .* Superimposed on the regional 

dip is a structural pattern of gently folded anticlines and synclines.

*Heyl, A. V., Jr., 1950, The Upper Mississippi Valley zinc-lead district: U. S. Geol. 

Survey open-file rept. 68.
190 CONTRIBUTIONS TO GEOCHEMICAL PROSPECTING FOR MINERALS

- v O

EXPLANATION

Area shown in detail on figure 27 Driftless area (Bean, 1949)

FIGURE 24. Index map showing boundaries of Driftless Area and of detailed index map

(fig. 27).

Behre, Scott, and Banfieia (1937, p. 788) state that the detailed 

structure consists of a series of elliptical basins which are from 1 to 5 

miles long and have a length to width ratio ranging frOttl 1:1 to 10:1, 

They also say (p. 795) that faulting, both normal and reverse, accompanies the shallow structural basins.

The ore deposits in the area are valuable almost entirely for their 

zinc and lead content, although a few carloads of copper ore have been 

shipped from several old prospects in the area. The primary minerals 2 are ankerite, barite, calcite, chalcopyrite, dolomite, galena, gold,

a Heyl, op. cit, p. 166-186.
-. STUDIES-IN SOUTHWESTERN WISCONSIN ZINC-LEAD AREA 191

marcasite, inillerite, pyrite, quartz, sphalerite, wurtzite(?), and an 

unidentified arsenic-cobalt mineral. Small amounts of cadmium, 

cobalt, silver, vanadium, germanium, molybdenum, and zirconium 

have been found in the ores. Principal secondary minerals are chalcocite, greenockite, cuprite, azurite, psilomelane, cerussite, smithsonite, hematite, limonite, malachite, melanterite, and aragonite.

Regarding the structure and stratigraphic occurrence of the ore 

deposits, Heyl (p. 9-11) says:

The largest number of the zinc deposits occur in the lower part of the Galena 

dolomite, in the Decorah formation, and in the upper half of the Platteville 

formation. The crevice-type lead deposits are limited to the Galena dolomite. 

Small lead, copper, and zinc deposits are found locally along the northern edge 

of the district in the Prairie du Chien group, and in places the St. Peter sandstone is pyritized directly beneath overlying zinc deposits * * *.

The ore deposits are divisible into two major varieties, gash-vein and pitchSILURIAN.. 

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Prosser cherty member

lon.dolomite member \ 

Guttenberg member y

Spechts Ferry shale member \ 

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'Pecatonica dolomite member

Glenwood shale member /

St. Peter sandstone

Prairie 

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Trempealeau

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Shakopee dolomite i

New Richmond sandstone

Oneota dolomite

Jordan sandstone member

St. Lawrence member

Franconia sandstone

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at base

 Dolomite, yellow, thin- bedded, shaly

Dolomite, buff, thick-bedded; 

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receptaculites near base

Dolomite, ,gray, argillaceous; 

limestone, pink, and

shale, light-green 

Limestone, pink, and carbo- , 

naceous shale, "glass rock"; 

limestone, gray, thin-bedded; 

dolomite, .gray-buff, .thick-bedded: 

shale, light-green, sandy

Sandstone, white. to brown

Dolomite, gray, locally cherty

Sandstone, white-lenses

Dolomite, gray, locally 

cherty, shaly, and sandy

Sandstone

Sandstone and dolomite

Sandstone '

FIGORB 25. Generalized stratlgraphic section of the Upper Mississippi Valley 

zine-lead district (after Heyl and others, 1955).

369614 56-
and-flat deposits. The gash-vein 8 deposits contain galena as the principal ore; 

in the underlying pitch-and-flat deposits, sphalerite is the important ore mineral 

and galena is a minor mineral. These sphalerite-galena deposits may be further 

subdivided into the arcuate and the linear type of ore bodies. Figure 3 * shows 

the main distinguishing features of these forms of ore bodies, and their stratigraphic relation to one another. In the gash-vein deposits the lead ore is 

deposited at favorable horizons along vertical joints and in cavities within 

partially dissolved, brecciated dolomite called "openings." In the underlying 

pitch-and-flat deposits the zinc-lead ores are banded veins within minor faults 

and fractures, and also replacements in the bordering rocks along the shear 

zones.

The stratigraphic units that contain most of the zinc deposits form 

an escarpment in the northern part of Grant and Iowa Counties (fig. 

27) and dip gently southward, so that they are commonly overlain 

by about 200 feet of rock near the Wisconsin-Illinois border. ;

PLAN

V

SECTION

Soil

100

GASH-VEIN DEPOSITS 

o

I I______________ I

200 Feet

PLAN SECTION

, Gash-vein deposits 

c j[. ff XKnot ' shown in Plan)

Decorgh formation 

(limestone and dolomite)

ff

400

PITCH-AND-FLAT DEPOSITS 

0 800 Feet

ICHJIUB 26. Diagrammatic plans ana sections illustrating typical patterns of gash-vein

lead deposits, and underlying pitch-and-flat zinc deposits of the arcuate and linear 

types, and their stratigraphic position relative to one another (Heyl and others, 1955, 

p. 234).

 Heyl's note is, "The use of the term 'gash-reins' for the jolnt:controlled lead deposits 

was suggested by Whitney (Hall and Whitney, 1862, p. 227). He stated: 'These deposits 

approach most nearly in character to what have been designated above as gashveins * V"

*A slightly revised- version of this Illustration is published in Heyl and others, 1955, 

p. 234. The revised version is figure 26 of this report. ;
^ ' r ::STtrr>IES"IN. SOUTHWESTERN WISCONSIN ZINC-LEAD AREA 193

A SURFICIAL GEOLOGY

*- A surficial layer of windblown silt or loess blankets the upland parts 

of the mining area, and widespread alluvium is present in many of the

**' stream valleys. The loess is commonly 2 to 8 feet thick, but in some 

areas it reaches a thickness of 15 feet or more. The detailed index 

map (fig. 27) shows the distribution and approximate thickness of 

the loess in the area in which these studies were made. In general,

» the loess deposits are thickest along the Mississippi and become thinner 

to the east. Locally the thickest deposits are on the hilltops and 

gently sloping uplands, and the loess thins gradually in the direction

^ of the stream valleys. On the slopes of steep-sided valleys the loess 

may be almost completely removed, even in areas of generally thick 

loessial cover.

* Chamberlin (1897, p. 799-801) suggested that the sources of the loess 

were the valleys of the Mississippi River and other glacier-fed rivers 

during the Pleistocene. He postulated that as the river was flooded

^ by melt waters from the glacier it spread silt over the flood plain. 

Then, as the river flow diminished, some of the silt dried and was carried to the southeast by the wind. G. D. Smith (1942, p. 152-162),

* who made a detailed study of the particle sizes and thickness of loess 

in Illinois, also concluded that the flood plains of rivers draining the 

glacier were the sources of the loess, inasmuch as both particle size 

and thickness increase as one approaches either the Illinois or Mississippi River. He found that the greatest thickness of loess was re-

** lated to sections of the rivers over which the wind had a fairly long

/ sweep across the river lowlands. His studies suggest that southwest

as well as northwest winds took part in the distribution of the loess.

As part of the present study, some data were gathered concerning

the mineralogy and thickness of the loess, and the amount of mixing

of the loessial material with the underlying residuum. In the Potosi

* area, where most of the samples for the loess-residuum studies were 

collected, the vertical profile of surficial material could be divided 

into five layers or zones on the basis of color, mineral composition, 

grain size, and reaction to concentrated hydrochloric acid. The samples were examined under a binocular microscope with a magnification 

of about 30. From the surface down, the zones are as follows:

Zone A. Partially weathered loess: a light-tan, well-sorted silt consisting primarily of quartz grains with a little mica and a few dark 

minerals; no effervescence in concentrated hydrochloric acid.

Zone B. Partially weathered loess: a very light-tan to almost white, 

well-sorted silt consisting mostly of quartz but with some dark 

^ minerals and a few mica flakes; in concentrated hydrochloric acid 

this material effervesces slowly at first but more rapidly after about 

15 seconds' contact, with practically no discrete effervescing particles visible. «
194 CONTRIBUTIONS TO GEOCHEMICAL PROSPECTING FOR MINERALS

EXPLANATION

 4 

Location of areas studied

1 Demby-Weist lead range (pi. 16)

2 North Dodgeville area

3 South Dodgeville area (fig. 28)

4 Linden area

5 Crow Branch (pis 8-11)

6 Trego mine

7 Potosi (pis. 11-15)

8 Champion property (fig. 29)

9 Crawford property (fig. 29)

DEPTH OF AEOLIAN SILT

Active sand dunes

FIGURE 27. Detailed index map showing the location of areas studied and the depth of

aeolian silt (loess). Depth after Hole, 1950.

Zone C. Partially weathered loess: very similar to Zone A.

Zone D. Residual clay: dark-red to brown mixture of day aggregates, quartz particles, chert fragments, and a few dark minerals; 

distinguished from higher zones by color, presence of clay aggre-
STUDIES IN SOUTHWESTERN WISCONSIN ZINC-LEAD AREA 195

gates, larger size of some of the quartz particles, absence of mica

flakes, and lack of effervescence in acid. 

Zone E. Partially weathered bedrock: almost white fragments of

dolomite and limestone distinctly larger than the particle size of the

loess; strongly effervescent in concentrated hydrochloric acid, with

effervescing particles easily visible.

All these zones were identified at some sample localities, although 

in many places one or more of the zones are missing. In general, the 

deeper the surficial material the more zones will be present.

The boundary between adjacent zones is marked by a gradual decrease in the proportion of material from one zone and an increase 

in the proportion of material from the adjacent zone rather than by 

an abrupt contact. The gradational character of these boundaries 

is important in evaluating the results of chemical analysis of soil 

samples because the dilution of residual material (zones D and E) 

with loess (zones A, B, or C), if not detected, can cause an incorrect 

interpretation of the amount of lead or zinc in residuum near known 

mineralized areas.

The following procedure was used for estimating the relative' 

amounts of loess and residuum in any soil sample: The sample was 

dried and crushed to pass an 80-mesh sieve. A part of this material 

was spread on white paper under a microscope and a drop of concentrated hydrochloric acid placed upon it. The reaction to acid 

serves to indicate the amount and type of calcareous material present 

and also to make it easier to see the individual grains. The presence 

or absence of iron-stained clay aggregates, chert particles, mica flakes, 

and various types of calcareous material .was noted and an estimate 

made of the percent of residuum present in the sample. This technique is useful principally for samples consisting of a mixture of loess 

and residuum. Material that is mostly either pure residuum or pure 

loess can be easily identified by simple megascopic observation of color 

and apparent clay content.

METHODS OF SAMPLING

WATER

The following methods were used in collecting water samples:

1. Spring and stream water: 50 ml of water were collected in a 

100-ml glass-stoppered graduated cylinder.

2. Farm wells: The well was pumped continuously for at least 10 

minutes either by hand or mechanically to remove as much contaminated water as feasible. A 50-ml sample was then collected 

directly from the pump in a 100-ml glass-stoppered graduated 

cylinder.

3. Drill holes: The water sample was collected in a steel bottle of the 

type shown in figure 30. The bottle was lowered to the required
196 CQNTRIBTCrriONS TO GEOCHEMICAL PROSPECTINQ FOR MINERALS

. depth in a drill hole, opened and filled, and then withdrawn from 

the drill hole and the water emptied into a 100-ml graduated glassstoppered cylinder.

SOIL

The soil samples were collected with a standard soil auger, consisting of one or more 3-foot lengths of %-inch pipe fitted with a 1*4- 

inch wood bit at the bottom, and a T-handle at the top. Ten to twentyfive grams of soil were collected from the required depth and placed 

in a paper envelope. These samples when dry, were pulverized in a 

porcelain mortar and passed through an 80-mesh sieve before analysis.

Sample points were laid out by tape and compass traverses and 

tied in to prominent land marks. Because most of the samples were 

collected in cultivated areas, it was not feasible to leave permanent 

markers at most of the sample sites.

ROCK

Samples were taken from churn-drill cuttings (by bagging a grab 

sample) as each cut was removed from the drill hole. Customarily 

in this mining district a sample of rock cuttings is removed at 5-foot 

intervals, but where unusual quantities of zinc and lead or a bed of 

particular interest is found, the cuttings may be taken at 1- to 2.5- 

foot intervals.

METHODS OF ANALYSIS

WATER

Huff's method (1948) of analysis for heavy metals in water was 

used. In brief, the method consists of shaking a known volume of 

water, which has been buffered to a pH of about 5.5, with 5 ml of a 

0.0016 percent weight per volume solution of dithizone in carbon tetrachloride. Copper, lead, and zinc are the most common elements reacting with dithizone under the conditions of the test. As little as

o.i microgram of zinc and 0.5 microgram of lead or copper in 50

ml of water may be detected by this method of analysis. The dithizone solution changes from the green of the pure state to a blue, purple. Or Ted) depending upon how much heavy metal is present. Because the heavy metals all have a similar reaction with dithizone, the 

resultant color is the sum of the effects of all the heavy metals. The

measured amount of heavy metals is expressed in terms of parts per

million (ppm), and a Sample Of water Which produces the same color 

in the dithizone solution as a sample of water containing 1 ppm zinc

is said to be i ppm in total heavy metak Zinc may be determined

specifically by adding sodium thiosulfate solution to the water before 

shaking.
STUDIES -IN SOUTHWESTERN WISCONSIN ZINC-LEAD AREA 197

: ' - i . . .. .... :. ".:SOIL / ' . . ' . '.'. ''

Lakin, Stevens, and Almond's method (1949) for zinc was used 

in all of the analyses made in the field. This test requires a potassium bisulfate fusion followed by an estimation of the zinc content 

by use of dithizone. In the laboratory several other methods of soil 

digestion were tried on selected samples under the supervision of 

Harold Bloom, and a digestion of a 0.1 g of soil for 1 hour in 2 ml of 

approximately 4 N nitric acid was found to be satisfactory for zinc 

determinations; in addition, the nitric acid extracted lead more consistently than did the bisulfate fusion. Before the amount of lead or 

zinc were estimated in the nitric acid solution, the solution was diluted 

to 10 ml. Not more than 3 ml of the diluted solution were added to 

8 ml of a buffer of the type used in the bisulfate fusion method for zinc; 

the estimation of the amount of zinc present was made by shaking the 

buffered solution with a dithizone solution and comparing the resultant colors with a series of standards similarly prepared. The lead 

estimate was made by the method described by Almond and Morris 

(1951, p. 613). .

In addition to the two field methods of analysis just described, a 

third method was tested on the samples from just one area. This 

method differed from the nitric acid method just described in that 

4 ml of 2 N nitric acid were used as the digesting liquid instead of 

2 ml of 4 N nitric acid. The samples digested by the third method 

were analyzed for total heavy metals essentially in the manner described by Huff (1951, p. 530) and for lead in the manner described 

by Almond and Morris (1951, p. 613).

Quantitative methods for lead, zinc, and copper modified from 

Holmes (1.945, p. 77-84) were used as the standards against which 

the various field methods were compared. These quantitative values 

are believed to be, in most instances, within 10 percent of the actual 

amount of lead or zinc present in the sample.

In evaluating the usefulness of the various methods of field analyses 

it must be realized that completeness of extraction is not the same for 

the different methods of extraction which were used. In comparison 

with the quantitative method, the zinc values obtained by the bisulfate fusion field method tend to be high, the 4 N nitric acid digestion 

gives results comparable to laboratory values, and the 2 N nitric acid 

method gives results that are low. For lead, the bisulfate fusion 

method gives low results, the 4 N nitric method slightly low results, 

and the 2 N nitric acid method erratically high and low results. Therefore, all of the samples from any one area should be analyzed by the 

same method in order to obtain comparable data. In areas where 

much lead and zinc are present, any of the methods of analysis de-. 

scribed will serve to detect them; however, the 4 N nitric digestion
198 CONTRIBUTIONS TO GEOCHEMICAL PROSPECTING FOR MINERALS

seems to give values for both lead and zinc that are close to the values 

found using the quantitative methods.

BOCK

The rock samples were analyzed for lead and zinc by the 4 N nitric 

acid method used for soils and were analyzed for iron by the o-phenanthroline method (Sandell, 1944, p. 271-273).

LEAD, ZINC, AND IRON IN ROCK AND SOIL OVER ZINC

DEPOSITS

In southwestern Wisconsin most of the lead deposits occur as vertical or nearly vertical veins, whereas the zinc ore bodies commonly 

have their longest dimensions in a nearly horizontal plane. The 

majority of the zinc ore bodies therefore, crop out only in the north-. 

.ernmost part of the mining district where the gently dipping host 

rocks are cut by the present erosion surface. Elsewhere, exploration 

for zinc deposits must be guided either by geologic structures or by 

some chemical or mineralogical feature of the overlying rock, such 

as a primary halo.

In order to determine whether primary halos occur in the strata 

overlying the zinc deposits, studies were made of the amount of 

lead, zinc, and iron in drill cuttings collected from strata above 

known ore bodies in the Shullsburg and Crow Branch areas (see fig. 

27). Samples of soil overlying the Crow Branch deposits, as well as 

other small, flat-lying zinc deposits, were also studied in an effort 

to detect secondary anomalies.

SHULLSBURG AREA

The Calumet and Hecla Mining Company made available their drill 

logs from the vicinity of two ore bodies and from areas believed to be 

barren of ore-grade mineralization. Estimates by the company geologists of the amoxint of zinc present as visible sphalerite, of lead 

occurring as galena, and of iron occurring as pyrite or marcasite were 

recorded from 5-foot cuts in the greater part of most drill holes, and 

for smaller cuts where the lead and zinc content was high. The lower

limit of macroscopic estimation of zinc as sphalerite and lead as galena, 

was approximately 0.1 percent, and of iron as pyrite or marcasite was 

approximately 0,25 percent. These data have been compiled in plate 7. 

A greater amount of pyrite, marcasite, and galena occurs in therocks overlying ore bodies than in equivalent rock units in "barren^ 

areas. Over one deposit, the visible sphalerite is more abundant in 

the rock above ore than in equivalent rocks in "barren" areas, whereas 

over one other deposit, the reverse relationship was found.
. STUDIES IN SOUTHWESTERN WISCONSIN ZINC-LEAD AREA 199

CROW BRANCH AREA 

SOIL SAMPLING

At Crow Branch (fig. 27, no. 5) a study was made of the lead and 

zinc content of soil in the vicinity of an area known to be well mineralized. The exact sources of the richest ore mined are not known; 

however, the most productive area is marked by several caved shafts 

and many prospect pits. The depth to the main ore-bearing beds 

gradually increases as one moves southeastward across the area studied. The ore cropped out in the stream valley at the north end of the 

Crow Branch area (see pi. 8), and lay about 110 feet below the surface near the southernmost shaft. Information concerning geologic 

structure and mineralization in drill holes, as shown in plates 8 and 9, 

was obtained from U. S. Geological Survey Circular 131.

Loess is present over most of the area studied at Crow Branch. In 

general the loess is thickest in the southeastern part where it reaches 

a maximum depth of about 6 feet. In the northern and southwestern 

parts erosion along the streams has stripped away both loess and residual soil, and bedrock is exposed.

In sampling soil from this area an attempt was made to get residual 

material, but in some samples a mixture of loess and residuum was 

collected as shown by later microscopic examination. When placing the analytical data on plate 9, the approximate amount of loess 

present in a sample was indicated by the method of plotting. Samples estimated to contain less than 20 percent residuum are not shown 

and samples estimated to contain from 20 to 50 percent residuum are 

plotted with a special symbol.

Despite the problem of sample dilution by loess, four geochemical 

soil anomalies were outlined by the data of plate 9. Anomaly A 

corresponds closely to the location of the old shafts and prospect pits, 

and anomaly B is related to a lead vein. The reason for the presence 

of anomaly C is not known, but it may represent a number of undiscovered lead veins, a second zinc sulfide deposit, or the effect of primary leakage of ore-bearing solutions moving upward along beddingplanes from the site of deposition of the main ore body. Anomaly D 

is also unexplained but may be the result of mineralization of the eastern limb of the Crow Branch syncline.

One of the reasons for choosing the Crow Branch area for detailed 

study was the fact that the depth from the surface to the ore-bearing 

level ranges from essentially nothing near the creek at the north end 

of the ore body to about 110 feet at the southernmost shaft. Thus 

ah opportunity was afforded for determining whether the size of the 

lead-zinc anomaly is related to the depth of the ore. The results obtained by soil sampling, as shown in plate 9', indicate no direct relation between the intensity of the geochemical anomaly and the depth

869014 56 3
to ore. The lack of much lead and zinc on the northernmost traverse, 

where the samples represent partially weathered bedrock taken only a 

few feet above the ore, is difficult to explain. Observations elsewhere 

show that anomalies in weathered rock are not so marked as those in 

residual soil, and this may, in part at least, account for the absence of a 

strong geochemical indication.of the ore at this locality.

BOCK SAMPLING

During the fall of 1949, after soil sampling had been completed at 

Crow Branch, both the U. S. Geological Survey and the Dodgeville 

Mining Company did some drilling there. The holes drilled at this 

time by the Survey are those numbered USGS 1A through 4 and 6 

and 7 on plate 9; those drilled by the Dodgeville Mining Company 

are numbered 1 through 6. Drill-hole numbers used for U. S. Geological Survey holes correspond to those used by Heyl, Lyons, and 

Agnew (1951, p. 7). Drill cuttings were collected from USGS 7 

and from Dodgeville Mining Company holes 5 and 6 (see pi. 9). 

The cuttings were analyzed for zinc, lead, and iron and the results 

are presented in plate 10. The cuttings removed from Dodgeville 

Mining Company hole 6 contained low concentrations of zinc, lead, 

and iron in contrast to the cuttings from the other two holes. The 

explanation for this contrast is believed to be the presence of sphalerite, galena, pyrite, marcasite, and their oxidation products in the 

rock near the main Crow Branch mineralized zone in concentrations 

large by Comparison with that at a distance from ore.

During the summer of 1952 the Dodgeville Mining Company drilled 

seven additional holes in a line cutting across the projected southeastern extension of the Crow Branch ore zone (see pi. 9). Samples 

of the drill cuttings were collected from each of the drill holes and

analyses were made for Zinc, lead, and iron. The analytical results

are presented graphically in plate 11. The data suggest that a lowgrade extension of the CrOW Branch ZOIie crosses the line of drill 

holes near Dodgeville Mining Company hole 9.

A comparison Of tKa iead and zinc concentrations in the soil near 

Dodgeville Mining Company holes 7-13 witu ^ concentrations of 

these elements in rock from these drill holes indicates that the anom- 

»ii«» i^ the rock correlate With the anomalies in the soil (pi. 9). 

TllUS the primary halo «*oou^ witlx tke Crow j^^ ore h0(Jy apparently can be detected by analyzing residual sou.

The lead and zinc Content of the rock in which the 

is present is, for the most part, less than 0.1 percent. This fact is 

important when evaluating the data on mineralization over ore in 

the Shullsburg area (pi. 7). At Shullsburg the lowest concentration 

of lead and zinc of which an estimate was made was about 0.1 percent. 

Thus the primary halos in the Shullsburg area may extend farther
STUDIES IN SOUTHWESTERN WISCONSIN ZINC-LEAD AREA 201

above the ore than was indicated by visual methods of estimating lead 

and zinc, for any primary mineralization over ore in the concentration 

range background to 0.1 percent would be missed by visual estimation. 

Comparison of the intensity and size of the primary halos of zinc, 

lead, and iron in Dodgeville holes 7-13 (pi. 10) shows that lead produces the smallest and least intense halo, zinc is intermediate in this 

respect, and iron produces the most widespread pattern. ' In thjs particular area the intensity of mineralization in the rock over the orejbearing layers appears to be related to the amount of ore present 

(compare Dodgeville holes 5 and 9 and USGS 7 with Dodgeville hole 

6, in pi. 10). '

: NORTH DODGEVILLE AREA ;

Soil samples were collected from 8 points on a 200-foot traverse 

crossing above a mined-out ore body at the northeast corner of Dodgeville. The traverse runs northward from Spring Street at a point 

approximately 1,000 feet east of the Dodgeville Mining Company 

shaft. The top of the ore was about 50 to 60 feet below the present 

land surface. Later microscopic examination showed that 2 of the 

soil samples collected had a high proportion of loess; so there were 

only 6 samples of residuum available for analysis. The lead content 

of these samples ranged from 70 to 1,700 ppm and averaged 650 ppm; 

the zinc content ranged from 200 to 1,100 ppm and averaged 590 ppm. 

The metal content of these soils is definitely higher than the normal 

background level of 15 to 30 ppm lead and 50 to 100 ppm zinc and 

strongly suggests the presence of a primary anomaly in the rocks 

overlying the ore.

SOUTH DODGEVILLE AEEA

Figure 28 shows in plan the location of known ore and the sample 

points where material consisting mostly of residuum was collected. 

Some samples found to consist primarily of loess or alluvium are not 

reported, and this accounts for the gaps in the data along some of the 

traverses. The crest of a low hill runs almost east-west through point 

E and the land slope is about 6° in a direction slightly east of south 

on the south side of the crest and about 10° to the north on the north 

side of the crest. The top of the ore lay at a depth of 70 to 80 feet 

on traverse GH, 110 to 120 feet on traverse EF, and about 100 feet 

on traverse AB. A correlation of metal-rich soils with underlying 

ore is marked in the GH traverse but is not apparent on traverses 

AB, EG, or EF.

Traverse IJ was made to see whether an extension of the ore zone 

could be located. Although the anomalies found near the east end 

of the traverse suggest a possible ore extension, drilling by the Dodgeville Mining Company after the soil sampling was completed did
202 CONTRIBUTIONS TO GEOCHEMICAL PROSPECTING FOR MINERALS

15. 15. .70 ' 

,50 80 200 100 

80

EXPLANATION

.30100

Location of soil sample

Upper number shows lead in parts per million 

Lower number shows zinc in parts per million

Mined-out ore body

Point referred to in text

0. 70- 2; 100

800.

250

188 . .30 ISs . * 60 15°

30 150

200 "~ 100

FIGURE 28. Lead and zinc content of soil near an ore body southeast of Dodgeville, Wis.

not show the presence of strong lead or zinc mineralization although

much iron was found.

LINDEN AREA

Six soil samples were collected over the Prairie mine about 1.2 

miles north of Linden (fig. 27, no. 4) to determine whether unusual 

amounts of lead and zinc are in the soil overlying an area where ore 

had been mined at a depth of about 75 feet. The results, though not

conclusive, indicate a slight lead anomaly above the ore, but no detectable zinc anomaly,

TRECrO MINE

A Study at the Trego mine, about 2 miles nortn oi riattevme ^ng.

27 7 no. 6) snowed normal amounts of lead and zinc in the SOll OVerlymg

the ore; this indicates that if any primary halo is present above the ore it te not extend to tne surlace oi Dedroct

The ore lay about 140 to 150 feet below the surface and the three 

short soil-sampling traverses crossed directly above the location of the 

ore body. Heyl (oral communication) states that the rock over the
STUDIES IN SOUTHWESTERN WISCONSIN ZINC-LEAD AREA 203

ore body did not seem to be highly fractured, and this suggests that 

open channel ways for the ore-bearing solutions did not extend far 

toward the surface.

LEAD AND ZINC IN SOIL OVER LEAD VEINS

In addition to a study of primary halos over zinc ore bodies and 

the secondary patterns derived from them, a study was made of the 

lead and zinc anomalies formed in soil during the weathering and 

erosion of gash-vein lead deposits. Because of the manner in which 

they are deposited, the gash-vein ore bodies are the ones most often 

found forming an outcrop, and it is this type of deposit which was 

studied to obtain information on secondary patterns formed near 

outcropping ore.

POTOSI AREA

In the Potosi area (fig. 27, no. 7), as in much of the southwestern 

Wisconsin zinc-lead area, a layer of loess covers almost all of the 

residual soil. The loess near Potosi reaches a thickness of at least 15 

feet on flat hilltops, but may thin to only a few inches on steep slopes. 

The loess has completely buried and preserved residual soil over areas 

many thousands of acres in extent. The result is that geochemical 

anomalies, if present in residual soil near lead veins, can be studied 

by augering through the loess and collecting residual soil samples. 

Because the loess is thick, this area offered an excellent opportunity 

to determine how far upward into the loess abnormal quantities of 

lead and zinc could be found where the underlying residual clay contains unusually large concentrations of lead and zinc.

A map of the general area studied near Potosi is presented in plate 

11. The locations of the many gash-veins which have been mined or 

only prospected are shown, and points where detailed studies were 

made are marked.

POINT J

Near point J a series of soil samples was collected across a lead 

vein which apparently contained only small quantities of lead near 

the surface. Kesults of analysis of these samples are presented in pi. 

13. In this area the land slope was so great that there was little 

residual clay present when the loess was deposited; also, much of the 

loess has been eroded since it was originally deposited. The soil then, 

consists of a layer of loess overlying partly weathered bedrock into 

which is mixed a small amount of residual clay. No galena was seen 

in any of the material thrown out of the prospect pits, and none of the 

soil samples contained high concentrations of lead or zinc. An examination of the data in plate 13 shows that, although the mineralization 

is slight, an unusual concentration of both lead and zinc is present in 

the soil near the prospect pits. The data indicate that there is also a
204 CoNTRiBUTiONS TO GEOCHEMICAL PROSPECTING FOR MINERALS

second, slightly mineralized, zone located in the vicinity of the sample 

taken 160 feet downslope along the traverse (see pi. 13), but there are 

no prospect pits on this zone. The secondary anomaly associated with 

this mineralized area is comparatively small, and sample spacing 

needed to detect such anomalies would be of the order of 20 feet.

POINT I.

The traverse south of point L is more nearly typical of the conditions near the tops of the hills than was the traverse near /. The 

depth of loess ranges from 7 to 9 feet and the thickness of residual 

clay and partially weathered bedrock combined ranges from 1 to 5 

feet. Plate 14 shows the results of the analysis of soil samples collected on this traverse. Anomalies found by soil analyses correspond 

well with the location of areas thoroughly prospected and, in some 

instances, mined by the early miners. Samples were not taken on 

the traverse between 100 and 170 feet because the iron-stained rock 

and soil on the surface indicated that the area had been dug over so 

much that an undisturbed soil profile could not be found. The fact 

that the residual soil samples downslope from this area contain more 

lead than the soil samples taken upslope from the disturbed area 

suggests that a source of lead is present in the area between 100 and 

170 feet along the traverse. The samples collected at the sample point 

60 feet along the traverse are obviously in disturbed ground, because 

unusual quantities of lead and zinc are present throughout the soil 

profile and microscopic examination showed the presence of residual 

soil in several of the samples. The high concentration of lead in the 

surface soil at this point can be correlated with the occurrence of pieces 

of galena in the disturbed soil.

Plate 11 indicates that several of the surface samples contain relatively large amounts of lead and zinc. Every surface sample which 

is high in lead and zinc content is in an area where bedrock and 

residuum were thrown to the surface during mining operations by

prospectors and later spread over the land by farmers leveling off 

the dump material.

Sampling on this traverse was done at much closer intervals than

would be necessary in prospecting a similar area, for sampling at 50- 

foot intervals would have identified this area as being mineralized.

Highest zinc concentrations were 5 to 8 times normal, and. lead, conGenerations were aS much RS 35 tUUCS HOrmaL

POINT M

Tlie traverse SOUtll Of point M OrVSSed. tKe crest of a. Kill on xvkioK tK©

thickness of loess was as much as 11 feet. Plate 15 shows a plan view 

of the sample points and of the lead veins which have been thoroughly 

prospected in times past, as indicated by a line of disturbed soil striking into the sampling area. In addition to the disturbed surface soil
STUDIES IN SOUTHWESTERN WISCONSIN ZINC-LEAD AREA 2ti5

associated with known veins there is a disturbed soil area at 150 feet 

: along the traverse. No line of old prospect pits trends into this area; 

so, it is-assumed that this is an isolated prospect pit.

The yein intersecting the traverse at 210,feet is the only one in .this 

particular area shown on the geologic structure map of the Potosi 

area (Heyl, Lyons, and Agnew, 1948); so presumably it is the most 

important vein in terms of lead production. Unusual quantities of 

lead and zinc are present in the soil in a zone 90 feet wide near this 

lead vein, but most of this zone is on the upslope side of the vein. 

Hence, .there is reason to believe that an additional source of lead :and 

zinc occurs upslope from the main lead vein. Possibly the disturbed 

soil at 150 feet marks the southern boundary.of this anomalous area.

Lead" is present in quantities slightly above normal in the soil near 

the sample points at 20 and 80 feet along the traverse. The anomaly 

at 20 feet is almost in line with some old prospect pits or shallow 

mines, but the anomaly at 80 feet has not been investigated by digging.

The concentrations of lead and heavy metals determined for the 

samples on this traverse were appreciably lower than those on other 

traverses because a mildly digested sample was used (2 N nitric 

acid digestion); nevertheless, areas containing much lead and zinc 

were detected. Zinc concentrations were obtained by using the bisulfate fusion method a method which entails much more thorough 

extraction than that used for the lead and heavy-metals tests.

CHAMPION AND CRAWFORD PROPERTIES

At both the Champion and Crawford properties (fig. 27, nos. 8, 9), 

the loess is generally thick and overlies what is known as a "lead 

range," or series of subparallel lead veins. The residual soil above 

these lead deposits contains unusually large concentrations of lead 

and zinc that are due to weathering of ore-bearing rock. Because 

of the mixing action during the formation of soil from rock, the area 

of soil in which much lead and zinc are found is larger than the area 

occupied by the lead veins themselves. Therefore the residual soil 

between lead veins contains unusual concentrations of lead and zinc. 

In such areas it is possible to determine the distance to which lead 

and zinc will move upward into the loess and also to get some idea 

of the method of movement, whether by mechanical mixing or by 

solution and redeposition. This is done by examing the loess microscopically for traces of the iron-stained residuum and by analyzing 

the loess chemically for traces of lead and zinc.

At the Champion property the Bureau of Mines had cut a deep 

trench across the lead range to bedrock. From this trench at one 

point near a known lead vein a series of soil samples was collected 

at 1-foot intervals in depth from the surface to bedrock. The lead
206 CONTRIBUTIONS TO GEOCHEMICAL PROSPECTING FOR MINERALS

CHAMPION PROPERTY

p-^-*6 SOIL DESCRIPTION

i

L -

\ ^

r \ ^ ~~ "- >- ~ -\ """~~> \ f

V. *1 ~ ^> >x x _

jT /

/ ^ ~

' J * 

>*^ «^ -~ """ ^

4,-r- -\-~i~T \ , , 1 . , 1

D 3000 6000 9000 12,000

^D OR ZINC. IN PARTS PER MILLION

EXPLANATION

~Lead~

Zinc 

Soil constituents in percent (estimated)

L. Loess

R, Residual clay

W. Partially weathered bedrock

95U5R

95U5R

50U50R

100R

100R

100R

100R

100R

90W;10R

CRAWFORD PROPERTY

0

i

2

3

4

5

5 6

u.

- 7

8

Q

9

10

U

12

13

"JfcJ*- SOIL DESCRIPTIC

r 100L

 100L

 100U

 100L

; -^lOOL

i^ v 95U5R

\ ^,

-\ ^>.^ 90R;10L

- ) ^> 95R.-SW*

/ *" *"

_/ *"*"""

1 /" *" *^ 70R;30W

/ 70R;30W 1

' 100W

l 

' in/iutf | 1UOW

| 

' 100W

1

14 U 100W

||

15 >' i i 1 i I...L.I i 1 i loow

O 3000 6000 9000 

LEAD OR ZINC, IN PARTS PER MILLION

PIGDBB 29. Relation of soil constituents to lead-zinc content at the Champion and

Crawford properties.

and zinc content of these samples are compared in figure 29 with 

the residuum content of the sample estimated by use of a microscope. 

Similarly, soil samples were collected from the side of a test pit 

dug by the Bureau of Mines on the Crawford property. These samples were examined to determine the relative amounts of loess and 

residuum and the information was compared with chemical analyses

(fig. 29).

Although the loess and residuum proportions shown In figure 20 

are only estimates, a correlation seems to exist between the estimated

residuum content and the lead-zinc concentration of the samples from 

both the Champion and Crawford properties. Therefore, it is probable that most of the lead and zinc in the lower 2 to 3 feet of loess 

is present because of mechanical mixing rather than because of upward movement of solutions carrying lead and zinc.

DEMBY-WEIST LEAD RANGE

The Demby-Weist lead range lies about T miles northeast of Dodgeville in the W^NW% sec. 28, T. 7 N., B. 4 E. (fig. 27, no. 1). The 

range consists of at least two veins from which galena has been

mined. Plate 16 shows the location of the sample traverse in respect 

to the westernmost vein and presents the results of analyses of soil 

samples for lead and zinc.
STUDIES IN SOUTHWESTERN WISCONSIN ZINC-LEAD AREA 207

An effort was made to auger to bedrock at each sample point, but 

at the eastern end of the traverse chert was struck in augering and 

bedrock was not always reached. Nevertheless, the essential fact is 

obvious that the soil near the known lead vein has a very high lead 

content. An examination of plate 16 clearly shows that there are high 

concentrations of lead and zinc in the soil to the west of the vein 

being examined. The anomaly at 370 feet from the beginning of 

the traverse is about 30 feet west of the known lead vein and, unless 

the present caved mine shafts are not directly on the known vein, 

probably indicates a new vein. The direction of soil movement is 

such that soil from the known lead vein would not produce the 

anomaly at 370 feet. Pieces of galena were found in the residual clay 

at this point at a depth of about 5 feet; thus the presence of unusually 

large concentrations of lead and zinc is shown both by unaltered ore 

minerals and by unusually large amounts of lead and zinc in the soil, 

as indicated by field tests. High values for both lead and zinc are 

present also at a point 300 feet along the traverse and may be indicative of another mineralized zone.

When the soil samples were first collected, only the bisulfate fusion 

test for zinc was used and the values shown in the upper half of 

plate 16 were obtained. When later experiments in other parts of 

this mining area indicated that lead tests were desirable, a series of 

samples taken along the traverse at depths of 1 foot, regardless of 

soil composition, was analyzed for lead as well as for zinc to see 

what sampling at some arbitrary shallow depth might show; also, a 

series of samples believed to be entirely residual material was analyzed. 

It is apparent from a comparison of the analytical results of samples 

from a 1-foot depth and samples of almost pure residuum that some 

anomalies detected by sampling residuum would have been missed by 

sampling done at a 1-foot depth. It is also apparent, especially from 

the analyses of residuum, that at the Demby-Weist lead range high 

concentrations of zinc are not necessarily accompanied by .similarly 

high concentrations of lead, although all high lead concentrations 

seem to be accompanied by high zinc concentrations. The data on 

residuum clearly show that unusual amounts of zinc are distributed 

throughout the area studied and that sampling, even at 200- to 300- 

foot intervals, would have shown this to be a mineralized area. With 

the exception of one or two samples, the lead contents also were at 

least three times the normal concentration of 15 to 30 ppm in 

residuum.

LEAD AND ZINC IN GROUND AND SURFACE WATER

In order to obtain some idea of the extent to which the heavy metals 

from the ore deposits in this mining area go into solution in ground 

water, waters from three different sources were obtained and analyzed.
208 CONTRIBUTIONS TO GEOCHEMICAL PROSPECTING FOR MINERALS

Samples of water from drill holes cutting ore, from holes close to 

ore, and from holes in so-called barren rock were collected and analyzed. Spring waters in the vicinity of Potosi were analyzed to determine what concentration of heavy metals in solution could be expected, 

near, and at some distance from, areas known to be mineralized. 

Stream waters were analyzed to see how well they reflected the heavymetal content of the springs and seepages constituting their source.

WATER FROM DRILL HOLES

; VV ater samples were collected and analyzed from drill holes bored 

primarily for prospecting purposes and also from drill holes being 

lised as farm wells. The study of water from drill holes was made 

almost entirely in the vicinity of Shullsburg because the Calumet and 

Hecla Consolidated Copper Company and the Vinegar Hill Zinc Company were conducting drilling programs there and water samples 

from their drill holes were readily available. A little experimentation 

indicated that the heavy-metal content (almost all zinc) of the water 

varied somewhat with depth in the drill holes. In order to permit 

sampling at any particular depth a special water sampler was designed for use in drill holes. A glass sampler with a cork stopper was 

built first, on the general principles shown in figure 30. This model 

burst when opened at a depth of 300 feet below the water table. Later 

a steel model was built which was coated on the inside with hot paraffin to prevent contamination. This sampler was found satisfactory 

for collecting water from any desired depth. The results of sampling 

water from drill holes located at various distances from ore are shown 

in plate 17. Ore is defined here as rock containing an average of 3 

percent of zinc through a depth range of 5 feet. The first five holes 

logged were not known to be near ore but, as in many holes drilled In 

this mining area, traces Of Sphalerite were seen in some of the drill

cuttings. The range of heavy-metal concentrations in Welter from 

these holes was from 0.02 to 0.08 and averaged 0.035 ppm. Holes 6 to

30 were those containing little or no recorded Sphalerite but W6r6

Known to be Within 200 feet Of drill holes penetrating ore. The a^erage heavy-metal concentration from these holes was 0.10 ppfll and tll6 

--~G~ ^^ o.o6 to 0.16 ppm. Drill holes 11-22 are known to penetrate

rock containing at least 3 percent »* «i~o «* ex a a^K ranffe of 

0 feet or more. The average heavy-metal content of the water in these 

holes was 0.08 ppm and the range was from 0.02 to 0.5 PPm.

As there is no » »y of knowir.g whether ore occurs near some of the 

drill holes penetrating barren or Only slightly mineralized m*, «~ 

concentrations above 0.02 or 0.03 ppm in holes 1-5 may indicate zinc 

mineralization nearby. The water from drill holes near but not penetrating ore shows abnormal concentrations of heavy metals in every
STUDIES IN SOUTHWESTERN WISCONSIN ZINC-LEAD AREA 209

Steel wire

Spring B 

Pin

Set screws.

Valve

-Pin A

-Spring A,

Spring B' 

in B'

^Cone-shaped 

bottle opening

.Steel semicircular 

brace

Steel bottiS

2 Inches

j

FIGURE 30. Steel water-sampler used in drill holes.

hole even though the known ore is located slightly downslope from 

some of the holes (as nos. 6-8). A possible cause of the anomalies in 

holes 6-8 is the proximity of the ore minerals to the water table; such 

proximity would be expected to result in an increased rate of oxidation
2J.O CONTRIBUTIONS TO GEOCHEMICAL PROSPECTING FOR MINERALS

and solution of both the ore body-and the scattered ore minerals found 

in the vicinity of the ore. Holes 9-10 are downslope from ore, but the 

ore is at a greater depth below the water table than it is in drill holes 

6-8, and active solution of the ore minerals is probably not rapid. 

Most of the drill holes penetrating ore do not contain unusually large 

quantities of heavy metals in the water everywhere throughout the 

hole. This suggests relatively little vertical mixing in the drill holes. 

Some of the water samples collected within a few inches of zinc-lead 

ore showed only a small increase in heavy-metal content over that 

found in slightly mineralized holes. The reasons for this are not 

known, but lack of oxidizing conditions may be the cause.

Two additional factors which have a bearing on the heavy-metal 

content of the water are the amount of turbidity and the difference 

of water pressure in the various beds. Some of the highest concentrations of heavy metals were found in water samples which were 

very turbid. It is possible that the buffer used in the water test 

caused the solution of small amounts of zinc from the minute particles 

of sphalerite undoubtedly present in suspension in some holes.5 Unfortunately, the importance of turbidity as a factor influencing the 

heavy-metal analyses was not realized until much of the work had been 

done, so that the lack of a notation in plate IT concerning turbidity 

does not indicate its absence. In fact, a perfectly clear sample was 

the exception rather than the rule, because lowering the sampling 

bottle down the drill hole usually stirred up fine particles that had 

settled out on the side of the hole after drilling was completed.

In some drill holes the observed differences in water pressure from

bed to bed appeared to be considerable. This phenomenon is not uncommon, according to A. F. Agnew (written communication), for

many drillers in the mining area have reported marked fluctuations of 

water level during drilling. If these pressure differences remained

after drilling was completed (and there are no verified records of this) 

there would certainly be vertical movement of water in the drill holes,

and a water sample collected at any specific depth would not necessarily represent the water present in the rock a foot or two away. 

This movement of water up or down a drill hole apparently did not 

cause thorough mixing of water throughout the hole for, as noted

preVlOUSly, Samples from different depths in the holes contained

different amounts of Keavy metals.

«An attempt was made to extract zinc from finely divided sphalerite in the laboratory by

Using the standard test for heavj- metals In water. Little or no zinc was extracted. When

similar sphalerite was shaken with distilled water and let stand for 3 days sufficient zinc

was dissolved to give a strong showing of heavy metals. The latter situation corresponds 

Closely to that present in the field during the analysis of water from drill holes.
.' .STUDIES IN SOUTHWESTERN WISCONSIN ZINC-LEAD AREA 211 

WATER FROM FARM WELLS

A study of the heavy-metal content of farm wells was included 

as part of the general study of ground waters. Relatively few 

samples were needed from farm wells to show that the running of 

water through the well pipes Avas not adequate to rinse them clean of 

dissolved heavy metals derived from metal in the plumbing. Of the 

water taken from 10 wells, none contained less than 0.2 ppm of heavy 

metals and 1, located in an area believed to be barren on the basis 

of drill holes surrounding it at distances of a few hundred feet, contained 7.5 ppm of heavy metals. The lowest concentration of heavy 

metals found in farm wells corresponded in amount to the higher 

concentrations found in drill holes penetrating ore, but 7 of 10 water 

samples exceeded any concentrations found in drill-hole water present 

near good zinc ore. One of the wells, when sampled, had been pumping for 4 hours and still had 1.0 ppm heavy metals, whereas another 

farm well contained only 0.2 ppm after 10 minutes pumping. Apparentry zinc from the piping, which is variable in amount, can obscure 

any natural concentration that may exist and the two cannot be distinguished. No way is known to determine the natural heavy-metal 

content of ground water drawn from the farm wells of this area.

A study of spring and stream waters was made in the Potosi area, 

with results shown in plate 12. Here the local relief is great enough 

for springs to be common, although the slopes generally do not exceed 

10° to 15°. Lead veins are abundant, especially on the hilltops, and 

the zinc-bearing beds are near enough to the water table for the zinc 

deposits to be oxidizing.

Plate 12 shows the results of spring, stream, and mine drainage 

analyses, as well as the location of lead veins and abandoned zinc 

mines.

Heavy-metal content was determined by the test devised by Huff 

(1948, p. 675-684), and the pH determined by indicator solutions and 

a Hellige comparator. The lowest concentrations of heavy metals 

found in spring water were of the order of 0.01 ppm, whereas those 

found in streams were less than 0.002 ppm. These concentrations 

can be used as the normal quantities on which to base a comparison 

of heavy-metal concentration in other samples taken in the same area. 

The heavy-metal content of some springs and streams was appreciably 

greater than normal, and a reasonable explanation for these anomalies 

is the presence of relatively large concentrations of heavy metals in 

the mass of rock from which the water was draining.

An examination of plate 12 shows that most springs containing 

abnormal concentrations of heavy metals are near known lead veins.
212 CONTRIBUTIONS TO. GEOCHEMICAL PROSPECTING iFOR MINERALS

The spring at point A (northeastern corner of map, pi. 12) contains 

about 0.45 ppm heavy metals and drains an area containing lead veins. 

To the south of this spring are other springs whose waters are uncommonly high in heavy-metal content, but no prospect pits were 

found upon a cursory examination upslope; thus there may be an 

undisturbed lead vein or zinc deposit nearby. At point B the water 

entering the stream from the north side contains more heavy metals 

than that coming from the south side. A possible explanation is the 

presence of a lead vein or an undiscovered zinc deposit just north of 

the stream.

The spring water near point 0 contained a greater amount of heavy 

metals than was found in the water from any other spring in the 

area not known to be draining a mined area. Soil samples taken 

near the lead veins lying upslope from this spring showed only normal quantities of zinc, and because zinc is the major heavy metal in 

the spring water, the lead veins, at least those exposed at the surface, 

do not seem to be the logical sources for the zinc, although there may 

be zinc present in them at depth. Alien V. Heyl (oral communication) pointed out that sphalerite is abundant in the Decorah formation 

at the adit located about 1,200 feet southeast of point 0 and that the 

sphalerite is present in a "replacement deposit of the 'pitch-and-flat' 

type." He suggested that a similar deposit may account for the zinc 

in the spring water at point C.

The owner of the spring near point G stated that small quantities 

of sphalerite had been taken from a shallow shaft a few hundred 

feet southwest of the spring. Unfortunately, this shaft could not 

be found.

Since the work described above was completed, drilling followed 

by development work has disclosed the presence of a rich zinc ore 

body lying under the hill to the south of point C (anonymous, 1955). 

The topography is such that drainage from part of the ore body would 

be toward the spring at point G.

Very probably the mine drainage at point D and the spring to the 

southwest of D contain unusually large amounts of heavy metals 

derived from the small quantities of lead and zinc minerals remaining after the mining operations.

The high concentration of heavy metals at point E is due to sewage 

from a cheese factory situated upstream from that point. The US6 

Of galvanized equipment may account for the zinc in the sewage. The

stream to the west of point F undoubtedly contains waters draining

from an area Of lead Veins lying to the north and northeast. The 

slight anomaly in the spring waters near point Cr cannot be explained 

by any lead veins that have been mined; however, there are a few 

old prospect pits upslope to the south of the spring and analyses
- STUDIES IN.SOUTHWESTERN WISCONSIN ZINC-LEAD AREA 213

of soil to the west of point G indicate that a mineralized zone strikes 

into the area lying upslope from the spring.

Because analysis of the stream near point H suggested that there 

was a source of heavy metals in the vicinity, five soil samples were 

collected along the east side of the stream and analyzed to see whether 

the lead vein striking into the area from the southeast continued 

through the suggested source area. Two of the soil samples contained 

10 times the normal amount of zinc and 5 to 10 times the normal 

amount of lead. The results of the soil analyses and the presence of 

a lead vein to the northwest of point H in line with a vein to the southeast indicate that the vein is continuous and is not broken into two 

separate segments.

At point /, the anomalous quantities of heavy metals in spring water 

may be derived in part from the lead veins lying upslope to the west 

of the spring, but drilling done after the water sampling proved the 

presence of zinc ore underlying the lead deposits. This zinc ore may 

be the main source of heavy metals in the spring water.

Beginning about 75 feet southeast of the spring near point /, six 

soil samples were collected on a line running northwest along the 

south side of the stream. The first sample was taken from the vicinity 

of several prospect pits (not shown on the map) and contained about 

20 times the normal amount of zinc and 10 times the normal amount 

of lead. The rest of the soil samples contained no more than 2 to 3 

times the normal amount of lead or zinc. Thus, it seems probable 

that the source area of the heavy metals in the spring water south of 

point / lies to the southeast of the spring. There is a possibility that 

the lead veins referred to in plate 13 and situated more than 200 feet 

south of the spring may be the main source of heavy metals, but this 

does not seem likely owing to the distance from the spring.

The spring at point K has a relatively large flow of water containing heavy metals (believed to be mainly zinc) in a concentration 

about 35 times background. The flow was estimated at 100 cubic feet 

per minute and a calculation was made of the amount of zinc being 

carried away in solution each year. On this basis 1,150 pounds of 

zinc per year are being removed in solution by the waters issuing from 

this spring.

At point N the drainage contains unusual quantities of heavy 

metals, but no lead veins that lie close enough to be an obvious source 

are mapped, although several prospect pits are shown. A series of 

4 soil samples taken about 200 feet upslope to the nor.th of point N 

showed that the soil contained more than 4 times the normal zinc content and 10 times the normal lead content. Therefore, there must be 

present at least low-grade mineralized rock which may be responsible 

for the heavy metals in the water.
214 CONTRIBUTIONS TO GEOCHEMICAL PROSPECTING FOR MINERALS

Examination of the map (pi. 12) will show possible causes of the 

anomalies found in most of the other springs and streams.

PRECIPITATION OF HEAVY METALS FROM SPRING 

AND STREAM WATER

One fact that may cause confusion in interpreting the analytical 

data presented in plate 11 is the precipitation of heavy metals from 

spring and stream water as the pH rises. The spring at point A is 

one example of this loss by precipitation. At the spring the pH is 

7.3 and the heavy-metal content 0.45 ppm, but as the water flows toward the main' stream, the heavy-metal content decreases and the pH 

increases. Similar removal of heavy metals from solution can be. 

noted at other springs in the large drainage basin in which spring A 

is situated.

The drainage from the spring near point G was examined in detail 

and the information obtained is shown in figure 31. The concentration of heavy metals decreases most sharply as the pH is increasing 

most rapidly, and the concentration of zinc in sediments is greatest 

where the zinc is precipitating most rapidly from the water. A calculation of the amount of zinc being precipitated, assuming that the 

heavy metals consist primarily of zinc, shows about 0.013 pound per 

day, or 0.4 pound per month, if the flow is correctly estimated at 10 

cubic feet per hour. From the information available in figure 31, an 

estimate was made of the total amount of zinc present in the first onehalf inch of silt and organic material in the spring drainage (the onehalf inch figure was chosen because that was about the depth to which 

the material was removed in sampling). The drainage area was estimated at 575 square feet, the average zinc content at 0.8 percent, and

the average specific gravity of the material as 1.5. Calculated on 

the basis of these figures, the amount of zinc present in the springdrainage in the top one-half inch of sediment would be approximately 

equivalent to that produced by 4 years of precipitation at the rate of 

0.4 pound per month. Although all of the data used in reaching this 

estimate are subject to much error because of variation in the rate of 

DreCipitatiOll. lOSS Of Zinc in Spring floods, and inaccurate estimates of

various values used in the calculations, it is quite probable that th& 

present Channels have remained relatively xinchaiiged for the last

several years, and that the precipitation of zlllC from the Welter JS llOt

an unusual, short-term phenomenon.

Correlation of the zinc decrease with the pH increase sllOuld not be

taken to indicate that the pH alone controls the amount of zinc in the

water, for some organic material is present in all of the streams and the 

most rapid loss of heavy metals from solution seems to be related to 

drainages where much decaying vegetation is present. Certainly, the
STUDIES IN SOUTHWESTERN WISCONSIN ZINC-LEAD AREA 215

EXPLANATION

Fine silt, decaying leaves, and some

moss over and through which spring water flows

Dense moss, silt and decaying leaves 

over and through which spring water flows

Number and location of sample point

20 Feet 

I

MAP SHOWING SPRING DRAINAGE

8 9 10 11 12 13

FIGURE 81. Precipitation of heavy metals from spring water near Point 0, Potosi area.

fact that several streams of pH 8.3 contain more than 0.05 ppm heavy 

metals indicates that the precipitation is not due to pH alone

SIGNIFICANCE OF THE DATA OBTAINED

The results of a study of the zinc and lead content of soils, rocks, 

and waters in the southwestern Wisconsin zinc-lead area indicate that 

geochemical prospecting techniques can be of value in prospecting
216 CONTRIBUTIONS TO GEOeHEMIGAL PROSPECTING7 FOR MINERALS 4

there. Where the lead and zinc minerals are at or near the water 

table and are undergoing oxidation and solution, it should be possible « 

to find anomalous amounts of heavy metals in springs nearby or in 

drill holes down the water-table gradient from the locus of mineralization. Analysis of streams is not so promising as analysis of springs 

because of the precipitation of heavy metals from streams; however, 

under certain circumstances, analysis of stream water is helpful. If 

part of an ore body or a zone of above-normal concentration of zinc -* 

and lead associated with an ore body extends to the surface of bedrock, 

analysis of residual soil will outline the zone of high zinc or lead 

content. y

The possible presence of loess in soil samples must always be considered, and extreme care should be taken to collect residual material. 

In areas where the loess is only a few inches thick, the mixing of it 

with the residuum by various natural agencies can be expected, and a 

gradation from a material consisting mainly of loess to one of essentially all residuum will be found. In such places there may be no 4 

clear-cut residual clay layer, and a slight variation in the depth of the 

sample or in completeness of soil mixing will change the proportions 

of residuum and loess, with a resultant difference in the significance 

of the analytical results. Where the loess is several feet thick, there 

is a gradation from essentially 100 percent loess to almost 100 percent 

residual material. Kegardless of whether the loess is thick or thin 

a general rule for sampling is to collect the sample from the residual 

clay zone lying just above the layer of partially decomposed bedrock. v 

If no clear-cut layer of clay is present, there is usually a layer of redbrown stained dolomite particles between the loess and the lightercolored, partially weathered bedrock. A sample of this material is 

not strictly comparable to one of residual clay, but it may suffice if 

no clay is present.

The ratio of lead to zinc, even along one mineralized zone, cannot 4 

be expected to remain constant. Although lead may be the better 

indicator of an anomaly at one point in the zone, zinc may be better 

in another; hence, generally both lead and zinc analyses are recommended in prospecting. However, if one is looking only for outcropping lead veins, only a specific test for lead is necessary.

A sampling distance of 50 feet is satisfactory for. general pros- y 

pecting in areas known to be at least slightly mineralized, but under 

Certain Conditions this distance can profitably be changed. On steep

hillsides where the trend of the mineralization is at right angles to 

the direction of slope and where the loess cover is gone and residuum

IS moving downslope rather rapidly, sampling distances down the

slope might well be increased to 100 feet or more. In a Similar topo- * 

graphical situation, if the trend of mineralization is parallel to the
 " r STUDIES IN SOUTHWESTERN WISCONSIN' ZINC-LEAD AREA 217

^ direction of slope and sampling is being done at right angles to the

t direction of slope, sampling distances of less than 50 feet might be

advisable. If the target is a long narrow one on rather flat land,

-1- as might be for lead veins on some of the hilltops, the pattern of lead

or zinc in the soil would be expected to spread only a little and

sampling at 25-foot intervals would be desirable. In general, a con-

/ sideration of the expected shape, size, and trend of the mineralized

n .zone and its relation to topography will make it possible to select

suitable sampling distances.

In reconnaissance work the sample spacing can be enlarged somewhat but probably should not exceed 100 feet. The fact that the 

chemical tests are semiquantitative and subject to occasional large 

errors means that it is desirable to space the samples more closely 

than would be necessary if the tests were always very accurate.

Areas in the vicinity of past mining activity may be suitable for 

prospecting because such areas are known to be mineralized and additional ore may be found by geochemical prospecting techniques. 

Geochemical evidence suggests that at the Demby-Weist property 

there is at least one additional unprospected lead vein near the known 

veins. At Crow Branch evidence was found indicating an extension 

of the mineralized zone about 1,000 feet to the southeast. Also, mineralized zones of economic interest may lie to the west of the main ore 

zone or to the east of the main ore zone on the east limb of the syncline, 

as suggested by moderately high concentrations of lead in the soili 

£' During the summer of 1952 the Dodgeville Mining Company drilled 

seven holes in a line across the projected extension of the main Crow 

Branch ore body and found that, although zinc or lead in minable 

quantity was not present, the mineralized zone did continue in the 

direction indicated by the geochemical work.

y RECOMMENDED METHODS FOR GEOCHEMICAL PROSPECTING IN

WISCONSIN

Prospecting for lead veins present beneath a cover of loess should 

be possible by means of soil analysis for lead and zinc. The broad 

and intense anomaly at the Demby-Weist lead range, the strong 

anomaly at the Champion and Crawford properties, and the lesser

^ anomalies in the Crow Branch and Potosi areas all indicate that 

above normal amounts of lead (and sometimes zinc) may be present 

in the soil near lead veins.

Zinc ore bodies, ranging in depth from 1 to about 100 feet below 

the surface may possibly be detected by the presence of lead and zinc 

in residual .soil derived from weathering of the mineralized rock

' -( overlying the ore. Of 4 ore bodies lying at depths of 50 to 100 feet 

below the surface at points where soil samples were collected all
218 CONTRIBUTIONS TO GEOCHEMICAL PROSPECTING FOR MINERALS

were indicated by concentrations of either lead or zinc or both in the 

residual soil. Of three ore bodies lying at depths of 100 to 150 feet 

below the surface at points where soil samples were collected one 

gave evidence of its presence by the unusual amount of lead and zinc 

in the soil. In some places above-normal quantities of lead and zinc 

were found over mineralized zones which were not of ore grade.

The analysis of spring water should also be of help in prospecting, 

especially in areas where there has been little or no mining activity. 

In the Potosi area anomalies were detected in the vicinity of minedout deposits as well as in areas not known to be near lead or zinc 

deposits. The presence of mining activity in the general vicinity 

did, however, raise a question as to whether the cause of an anomaly 

was a previously undiscovered mineralized area or whether it was a 

deposit which had already been mined. In an undisturbed area the 

presence of unusually large quantities of heavy metals in spring 

water would very probably indicate an undiscovered mineralized area. 

However, if zinc deposits are to be found by the analysis of spring 

waters, they must be at relatively shallow depths where oxidation 

and solution of the zinc minerals will be relatively rapid.

The use of stream analysis in prospecting .may be of value .at. times 

when sampling of the individual springs supplying the stream with 

water is not feasible. In a few instances the author found that a 

stream gradually increased in size because of the presence of a great 

many small springs instead of a few large ones. Under these circumstances the best policy ;seems to be to 'sample the larger of the springs 

and also to sample the stream at regular intervals. In general, however, the fact that heavy metals tend to precipitate from solution 

shortly after water reaches the land's .surface means that sampling 

should be done at the spring if possible.

SOME METHODS OF PROSPECTING NOT RECOMMENDED

The analysis of farm wells for heavy metals as a means of prospecting is not promising nor is the analysis of water from drill holes promising in areas where the ore-bearing horizons are more than 100 feet 

below the water table. Because of the oxidation and solution of the 

zinc from galvanized pipes, the water from farm wells is relatively 

high in total content of heavy metals and the small amount of zinc 

which might be derived from an ore body nearby cannot be distinguished from that derived from a galvanized pipe. Although, under

favorable circumstances, it may be possible to obtain anomalous

quantities Of heavy metals in ground water near ore bodies lying more 

than 100 feet below the water table, this is not a promising method 

of prospecting for general use.
STUDIES IN SOUTHWESTERN WISCONSIN ZINC-LEAD AREA 219 

SOME UNSOLVED PROBLEMS

As in> much research, problems developed which were not solved. 

Some of these should be studied before serious prospecting is done, 

and others are not of such immediate importance.

Before extensive prospecting for lead veins can be done, some experimentation with rapid methods of collecting the sample should be 

performed. A power auger probably would serve the purpose, but no 

equipment of this type has been tried by the author. It is known 

that augering by hand in deep loess would be prohibitively expensive 

in time and effort.

The frequency with which primary halos of the type found at Crow 

Branch may be expected above zinc ore bodies has not been determined. That such a primary halo commonly is present is indicated 

by the results over the five ore bodies which were studied. The dependability of this phenomenon should be established before any 

conclusions regarding its usefulness in prospecting can be drawn. 

Furthermore, many more ore bodies must be studied before any definite 

conclusion can be reached about the vertical and horizontal dimensions of the primary halos.

No effort was made to determine what elements other than lead, 

zinc, and iron are disseminated near ore bodies, but such a study seems 

desirable. Unusually large quantities of chert were found in the 

residual soil overlying the North Dodgeville, South Dodgeville, and 

Crow Branch ore bodies. This suggests silica as being part of a 

primary halo. The presence of much chert may not necessarily mean 

mineralization, for there are certain beds which contain concentrations of chert and these, when weathered, produce cherty soils. Nevertheless, in the three areas mentioned, the soil not lying over the mineralized zones showed little or no chert, but the soil over the ore 

contained so much chert that hand augering was difficult, and, in a 

few instances, impossible.

In only one instance were water samples collected from drill holes 

bored near an ore body lying close to the water table (drill holes 

6-8, pi. IT). The oxidation and solution of the disseminated ore 

minerals in the vicinity of the ore probably produced the abovenormal concentrations of heavy metals in ground water. This, if common, could be very useful in prospecting for shallow ore bodies. 

Sufficient work has not been done, however, to determine in any detail 

what the relation of the ore body to the water table must be in order, 

to produce such anomalies.

Many more problems could be stated, but the author believes that 

the solution of the ones listed above would provide much help in 

prospecting by geochemical methods.
220 CONTRIBUTIONS.'TO GEOCHEMICAL PROSPECTING FOR MINERALS 

: CONCLUSIONS

Geochemical methods of prospecting show definite promise as a 

tool for the geologist searching for ore deposits in southwestern 

Wisconsin. The data obtained by analyzing natural soils, rocks, and 

waters in the vicinity of known ore indicate that there are abnormally 

high concentrations of lead, zinc, and iron present in these materials 

near hidden ore deposits. Although further research seems necessary 

before geochemical techniques can be used to the fullest advantage, 

the information obtained thus far should be of help in prospecting 

at the present time.

LITERATURE CITED

Almond, Hy, and Morris, H. T., 1951, Geochemical techniques as applied in recent

investigations in the Untie district, Utah: Econ. Geology, v. 46, no. 6, p.

608-625. 

Bean, E. F., 1949, Geologic map of Wisconsin: Wis. Geol. and Nat. Hist. Survey,

1 map.

Behre, C. H., Jr.. Heyl, A. V., Jr., and McKnight, E. T., 1948, Zinc and lead deposits of the Mississippi Valley: 18th Internat. Geol. Cong., Kept. 18th Sess.,

pt. 7, p. 61-69, London [1950]. 

Behre, C. H., Jr., Scott, E. R., and Banfield, A. F., 1937, The Wisconsin lead-zinc

district, preliminary paper: Econ. Geology, v. 32, p. 783-809. 

Chamberlin, T. C., 1897, Supplementary hypothesis respecting the origin of the

loess of the Mississippi Valley: Jour. Geology, v. 5, p. 795-802. 

Hall, James, and Whitney, J. D., 1862, The geology of Wisconsin: Wisconsin

Geol. Survey, v. 1. 

Harbaugh, J. W., 1953, Geochemical prospecting abstracts through June 1952:

U. S. Geol. Survey Bull. 1000-A. 

Hawkes, H. E., 1950, Geochemical prospecting for ores, in Trask, P. D., Applied

sedimentation, p. 537-555, New York, John Wiley and Sons. 

Heyl, A. V., Jr., Lyons, E. J., and Agnew, A. F., 1948, Geologic structure map of

the Potosi lead-zinc area, Grant County, Wis.: U. S. Geol. Survey Strategic

Minerals Invest. Prelim. Map 3-221,1 map.

 1951, Exploratory drilling in the Prairie du Chien group of the Wisconsin 

zinc-lead district by the U. S. Geol. Survey in 1949-1950: U. S. Geol. Survey 

Circ. 181, p. 7-9, 17-22.

Heyl, A. V., Jr., Lyons, E. J., Agnew, A. F., and Behre, O. H., Jr., 1955, Zinc, lead, 

copper resources and general geology of the Upper Mississippi Valley district : U. S. Geol. Survey, Bull. 1015-G.

Hole, EV r>.. 1950, Areas having aeolian silt and sand deposits in Wisconsin: 

Soils Div,, Wis. Geol. and Nat, Hist. Survey, 1 map.

Holmes, R. S., 1945, Determination of total copper, zinc, cobalt, and lead in soil 

and soil solutions: Soil Science, v. 59, p. 77-84.

Huff, L. C., 1948, A sensitive field test for heavy metals in water: Econ. Geology, 

v. 43, no. 8, p. 675-684.

 1951, A sensitive field test for detecting heavy metals in soil or sediment: 

Econ. Geology, v. 46, no. 5, p. 524-540.
STUDIES IN SOUTHWESTERN WISCONSIN ZINC-LEAD AREA 221

Lakin, H. W., Almond, Hy, and Ward, F. N., 1952, Compilation of field methods 

used in geochemical prospecting by the U. S. Geological Survey: U. S. Geol. 

Survey Circ. 161.

Lakin, H. W., Stevens, B. E., and Almond, Hy, 1949, Field method for determination of zinc in soils: Econ. Geology, v. 44, no. 4, p. 296-306.

Sandell, E. B., 1944, Colorimetric determination of traces of metals: New York, 

Interscience Publishers, Inc.

Smith, G. D.f 1942, Illinois loess variations in its properties and distribution: 

Illinois Univ. Agr. Exper. Sta. Bull. 490.

Anonymous, 1955, American zinc active in Wisconsin: Skillings Mining Review, 

v. 44, no. 3, p. 8.

INDEX

Page 

Abstract __ ............... 187

Acknowledgments-.. _ . 187-188 

Alluvium................. . ..._ ... 193

Analysis, rock......... . . 198

SOU...... . . . 197-198

water .. ..... ............... 196

Anomaly,.primary...... 188-189,198,201,219

secondary!... . - - 188-189,198,20,4 

Auger, standard soil... .. 196

"Barren" areas 198 

Basins, elliptical. .. ........ .. 190

Bisulfate fusion test for lead and zinc 197,207

Calument and Hecla Consolidated Copper

Company...____....... 188,198,208

Champion property . . ... 205-206 

Chert-- 194,195,219

Churn-drill cuttings . ----- ... 196

Clay, residual.. ............... 194,203,204,216

Conclusions__ . 220 

Copper.____________.__...__. 190,196 

Crawford property ......... 205-206

Crow Branch area..__.__ .......... 199,217

Crow Branch syncllne_.... _ . 199,217

Demby-Weist lead range.. . . 206-207 

Dithizone, use in test for zinc. . .. 196,197 

Dodgeville Mining Company...... .. 200,201,217

Driftless Area.---.--..------------.--- 189,190

Drillholes, water sample______-___ 208.210

Galena. . 190,192,198,200,203,206,207 

Gash-veins-..--.-_____ _ . _ 192,203

Geochemlcal prospecting, nonrecommended

methods_____ ._ ...... 218

recommended methods__....__..__ 217-218

Geology.-.-.---.__ .._... 189-195,pi. 8 

bedrock... . 189-192 

surflcial-- .................. 193-195

Grant County_________________ 192

Halo, geochemical- . . .. 188-189,201 

Heavy metals.......... 187,196,197,205,208,210-219

Hellige comparator .... . 211

Introduction... .. . 187 

Iowa County.....-.-- ... .. 192

Lead, deposits_____ ._ . ... 198 

in ground andsurfacewater. 207-214 

in soil over lead veins.___ __...... 203-207

"Lead range".-. - 205 

Linden.area_____....__ __..__. . 202

Page 

Literature cited.. ......._........_. 220-221

Loess... 193-195,199,203,205,206,218

Minerals, primary _ _ __.__ 190-191 

secondary.... . .... 191

 Nitrjc acid, use in test for zinc.. _.__.. 197 

NorthuDodgeVllle area_ __._______ 201

Ore, zinc content of 208

Patterns, chemical dispersion_______ 188-189 

pH, effect on heavy metal precipitation.... 214-215

Pitch-and-flat deposits.. . .. .... 192

Point J ............................. 203-204

Point L._.................................. 204

Point M._._.____.....____....... 204-205

Potosi, Wisconsin....... __ _.___ 187

Potosl area... 193,203-205,211

Prairie mine_________________ 202 

Precipitation, heavy metal from spring and

..- stream rwater..__.._____ 214-215 

Problems, unsolved.__.___.______ 219 

Purpose of Investigation..___ _____ 188

Kesiduum... ...... 193,195,201,206,207,216

Sampling distance . . ... 196,216-217 . Sampling methods, rock_________ 196,200-201

soil 196,199-200

water_______________ ____ 195-196 

Shullsburg area... . .. 198 

Sigriiflcan'cVof data'obtained........_.... 215-217

Sodium thiosulfate solution .. .... _ 196

South Dodgeville area...................... 201-202

Sphalerite . 198,200,208,212

Springs, precipitaton of heavy metals..._ 214-215

water sample__ .. 211-214 

Streams, precipitation of heavy metals.. _ 214-215

water sample. . 211-214

Topography___.__...._..__..._ ._ 189-195

Trego mine______________. ___ 202-203 

Turbidity, effect on water analysis. _____ 210

Vinegar Hill Zinc Company....------- 188 208

Water, heavy metal content . . 207-215

Water sampler, glass. _____________ 208

steel - . . 208,209

Wells, water sample. . ....__.._ 211

Zinc, deposits- _________.______ 198 

in ground and surface water. __..... _ 207-214 

in soil overhead"veins... ... 203-207

o

223