A Geochemical Reconnaissance for 

Gold in the Sedimentary Rocks of 

the Great Lakes Region, 

Minnesota to New York 

By DAVID A. SEELAND 

GEOLOGICAL SURVEY BULLETIN 1305 

Atomic-absorption analyses indicate 

an absence of fossil placers and 

relatively abundant but noneconomic 

amounts of gold of syngenetic 

chemical(?) origin in marble and 

glauconitic sandstone 

UNITED STATES GOVERNMENT P RINTING OFFICE, WASHINGTON:l973 
UNITED STATES DEPARTMENT OF THE INTERIOR 

ROGERS C. B. MORTON, Secretary 

GEOLOGICAL SURVEY 

V. E. McKelvey, Director 

Library of Congress Catalog-card No. 73-600244 

For sale by the Superintendent of Documents, U. S. Government Printing Office 

Washington, D. C. 20402- Price 35 cents (paper cover) 

Stock Number 2401-02411 
CONTENTS 

Page 

Abdrnct ------------------------------------------------- 1 

Introduction ---------------------------------------------- 2 

Acknowledgments ---------------------------------------- 6 

Clastic rocks ---------------------------------------------- 6 

Precambrian clastic rocks----------------------------------- 6 

Paleozoic clastic rocks------------------------------------- 8 

Pleistocene clastic sediments --------------------------------- 9 

Chemic~rocks -------------------------------------------- 9 

Precambrian carbonate rocks -------------------------------- 9 

Paleozoic chemical rocks ----------------------------------- 11 

Summary and conclusions ------------------------------------- 11 

References cited -------------------------------------------- 15 

ILLUSTRATIONS 

Page 

FIGURE 1. Map of Northeastern United States, showing collection areas of samples_ 5 

2. Histograms showing frequency distribution of gold in analyzed 

sedimentary rocks from the Great Lakes region _____________ 13 

TABLES 

Page 

TABLE 1. Gold content of clastic rocks of the Great Lakes region_____________ 7 

2. Gold content of chemical rocks of the Great Lakes region ___________ 10 

3. Number, percentage, and mean gold content of analyzed samples with 

detectable gold by rock type --------------------------- 12 

III 

A GEOCHEMICAL RECONNAISSANCE 

FOR GOLD IN THE 

SEDIMENTARY ROCKS OF THE 

GREAT LAKES REGION, 

MINNESOTA TO NEW YORK 

By DAVID A. SEELAND 

ABSTRACT 

Fossil placers were sought in the Precambrian and Paleozoic sedimentary rocks of the Great 

Lakes region of the North Central United States. The gold-mining area of the Canadian Shield 

north of the Great Lakes was postulated to be a primary source of particulate gold that should 

have been carried down the southward-dipping paleoslope into the Great Lakes region by 

fluvial and marine currents. However, of 777 10-gram samples analyzed by cold extraction -atomic absorption (lower limit of detection, 0.020 part per million gold) and 22 10-gram 

samples analyzed by fire assay (lower limit of detection, 0.025 part per million), only 36 (4.8 

percent) had detectable gold; and in the 36 samples the modal gold content was only 0.020 part 

per million. An overall arithmetic mean of 0.0087 part per million gold for the 799 analyzed 

samples was calculated by use of a statistical technique applicable to data in which there is a 

large proportion of samples in the "not-detected" class. Inasmuch as 95-percent censoring extends the technique to its limits, the mean should be accepted with reservations. 

The arithmetic mean of 0.0087 part per million gold is so small that the presence or absence 

of a single minute flake of gold in a sample gives results that are, respectively, too high or zero. 

Because of this problem, meaningful gold analyses or gradients were not obtained. A possible, 

but impracticable, solution to the problem would be the collection of samples weighing 120 

kilograms and the separation and analysis of the heavy-mineral fraction. 

The relative amounts of gold in each of the sampled rock types can be estimated by comparing the percentage of samples that contain detectable gold for each rock type. The percentage of gold found in the sampled rock types that contained gold follows: nonglauconitic 

sandstone, 1.0; shale, 3.1; limestone and dolomite, 3.3; conglomerate and conglomeratic 

sandstone, 6.7; glauconitic sandstone, 16.7; and marble, 24. Glauconitic sandstone samples are 

from the Franconia Sandstone in Wisconsin, and the marble samples are from the Grenville 

Series in the Adirondack Mountains in New York. Gold was also detected in gypsum and 

halite samples, but the sample size was too small for the percentage to be significant. 

The frequency with which gold was detected in the chemical rocks of the region suggests the 

possibility that certain undetermined syngenetic chemical processes have concentrated 

anomalous amounts of gold in rocks of chemical origin. These chemical processes may be more 

effective concentrators of gold than the expected placer-forming physical processes, even in a 

region relatively close to a source of clastic gold. Possibly, also, the general lack of gold and the 

small grain size of the gold that was found (less than 5 percent of the hydraulic equivalent size 

in the nonglauconitic sandstone-quartzite category) are results of postdepositional leaching. 

The apparent abundance of chemically or biochemically precipitated gold and the relative 

lack of clastic gold in a region close to a major gold source could also be explained by the 

presence of an east-west late Precambrian-early Palezoic continental divide just north of the 

Great Lakes separating a known south- and southeast-trending paleocurrent system from a 
2 GOLD, SEDIMENTARY ROCKS, GREAT LAKES REGION 

probable north-trending system. Most Canadian Shield gold deposits would lie north of this 

divide, and the logical place to look for fossil placers would then be in the basal Paleozoic 

clastic rocks near James Bay. 

INTRODUCTION 

The project was initiated in hopes of finding fossil gold placers in the 

clastic rocks of the Great Lakes region. The postulated source for the fossil 

placers is the rich Canadian Shield Precambrian gold area north of the 

Great Lakes. Canada at one time supplied about 13 percent of the world's 

annual gold production (Bateman, 1950, p. 437), and about 80 percent of 

this production was from just north of the Great Lakes in western Quebec 

and Ontario. 

Prior to Mississippian time the Canadian Shield was the chief source of 

clastics for the area from Minnesota to northern New York; during and 

after the Mississippian, the northern Appalachian Mountains were a major 

source of clastics for the Illinois and Michigan basins and adjacent areas, 

and the Canadian Shield was a minor source area (Potter and Pryor, 1961, 

p. 1226). Paleocurrents inferred from crossbed orientations determined during the study confirm the general southerly transport direction in the Great 

Lakes region during the early Paleozoic. Divergences from this general 

trend are present. In northern New York on the northwestern margin of the 

Adirondack Mountains, crossbed orientations indicate an easterly, or 

Adirondack Mountains, source for the Cambrian Potsdam Sandstone. In 

contrast, on the northeastern and eastern margins of the Adirondack Mountains, crossbedding indicates a northerly to northwesterly source area for 

the Potsdam. 

Late Precambrian-Cambrian paleocurrents of the United States and 

western Canada were perpendicular to the continental margins, and they 

transported sand radially from the interior toward the ocean basins 

(Seeland, 1969, p. 271). Then, by analogy, there were northerly currents 

along the north edge of the continent which were separated from the 

generally southerly currents of the Great Lakes region by a continental 

divide. If this divide was north of the major gold deposits of the Canadian 

Shield, fossil placers could exist in the sedimentary rocks of the Great Lakes 

region. If the postulated divide was south of the major gold deposits, fossil 

placers very likely could not exist on the southern margin of the Canadian 

Shield. 

An initial reconnaissance sampling of the clastic sedimentary rocks of the 

region determined the feasibility of establishing gradients of gold abundance in one or more of the formations sampled. Because gold was detected 

in only 9 of the 204 original samples, gradients clearly could not be obtained 

from unconcentrated samples of these clastic rocks. As analytical results on 

additional rock types were obtained, it slowly became evident that quartzose clastic rocks contained less gold than chemical and biogenic rocks, 

such as marble, limestone, and glauconitic sandstone. 
INTRODUCTION 3 

Samples were collected in Minnesota, Wisconsin, Michigan, Iowa, 

Illinois, Missouri, Kentucky, Ohio, Pennsylvania, Virginia, and New York 

(fig. 1 ). Chip samples were collected at most outcrops. Channel samples 

were taken in poorly cemented rocks. The field samples were reduced, if too 

large, to several hundred grams; these were ground to pass through a No. 

100 U.S. Standard sieve mesh (less than 0.149 mm), and a 10-g (gram) split 

was analyzed for gold. The lower limit of detection was 0.020 ppm gold for 

the 777 10-g samples analyzed by solvent extraction -atomic absorption 

techniques (Lakin and Nakagawa, 1965) and 0.025 ppm gold for the 22 

samples analyzed by fire-assay methods. 

The locality, stratigraphic unit, lithology, and gold analyses for all 

samples collected during the field investigations have been tabulated 

previously (Seeland, 1973). 

A problem related to that of analytical sensitivity is the problem of 

analyzing for low concentrations of particulate gold where the analytical 

results depend on the presence or absence of a gold particle rather than on 

the actual gold .content of the rock unit from which the sample was 

collected. This problem has been termed the particle-sparsity effect by Clifton, Hubert, and Phillips (1967, p. 2); papers by Clifton, Hunter, Swanson, 

and Phillips (1969) and Tourtelot (1968) provide a basis for evaluating its 

effect on this study. Because nearly half the samples collected were 

sandstone, the particle-sparsity effect is applied to the analytical results for 

sandstone. 

Jones (1969, p. 22) reported neutron-activation analyses of 24 sandstone 

samples from 9 different areas in which the gold content averaged 0.0075 

ppm and ranged from 0.0006 to 0.041 ppm. DeGrazia and Haskin (1964, p. 

562) analyzed five sandstone and quartzite samples for gold by a neutronactivation technique and arrived at a "characteristic" gold content of 0.006 

ppm after discarding a sandstone sample (0.041 ppm) from the Kettleman 

Hills, "a placer deposit." 

The minimum sample size necessary to obtain statistically reliable results 

is based on the number of gold grains which in turn is based on the weight of 

the grains and the gold content of the rock. 

The diameter of a gold sphere hydraulically equivalent to medium sand 

(0.37 mm) is 0.075 mm (Tourtelot, 1968, fig. 1). If it is assumed that a gold 

flake with a 5:1 ratio of diameter to thickness represents the actual shape of 

the gold grain, it can then be determined that the hydraulic equivalent of the 

the 0.075-mm gold sphere is a flake 0.13 mm in diameter and 0.026 mm 

thick (Tourtelot, 1968, fig. 3) which weighs about 6X 10-6 g. 

To determine background values of gold as low as 0.001 ppm in 

sandstone containing gold particles weighing about 6X 10-6 g, a 120-kg sample containing 20 gold grains is required for 95-percent certainty that the 

true gold content varies no more than 50 percent from the analytical results 

obtained (Clifton and others, 1969, fig. 3). This is clearly impractical for a 
4 GOLD, SEDIMENTARY ROCKS, GREAT LAKES REGION 

reconnaissance effort, inasmuch as 799 samples that each weigh 120 kg (264 

lb) weigh 95,700 kg (211,000 lb) in aggregate, and the rock would have to 

be ground and the gold separated prior to analysis. 

Although the samples may be too small for reliable results, limits can be 

put on the gold content and gold-particle size of the sampled nonglauconitic 

sandstone and quartzite units. Assuming that the gold flakes are the 6X 10-6 

-g hydraulic equivalents of medium sand and that the sampled units contain 

the 0.006 ppm gold thought by DeGrazia and Haskin ( 1964, p. 562) to be 

characteristic of sandstone, then in 100 samples of 10 g each, 1 sample will 

contain an entire flake of gold; this is quite close to the 1 in 104 nonglauconitic sandstone samples that actually do contain detectable gold. 

However, a 6X 10-6

-g gold flake in a 10-g sample amounts to 0.6 ppm gold, 

whereas a 10-g sample with 0.031 ppm gold (the mean for three positive 

analyses from 312 nonglauconitic sandstone and quartzite samples) contains a gold particle that is only 5 percent as large as the hydraulic 

equivalent size if it is assumed ( 1) that each positive analysis is due to a 

single flake of gold (probably true in many cases), and (2) that all flakes are 

large enough to have been detected at the lower limit of detection (possible 

but not probable). As a result of the second assumption, the calculated 

mean particle size is likely to be too large. This combination of assumptions 

and analytical results also permits calculation of a minimum mean gold 

concentration of 0.0003 ppm in the sampled nonglauconitic sandstone and 

quartzite units. In summary, the mean gold content of the nonglauconitic 

sandstone and quartzite units sampled is greater than 0.0003 ppm but less 

than 0.031 ppm, and individual gold particles weigh less than 3 X 10-7 g, or 

less than 5 percent of the hydraulic equivalent size. 

The validity of the difference between the apparent and the calculated 

hydraulic equivalent gold-particle size might be questioned because the 

samples are ground to minus 100 mesh before analysis, but experimental 

evidence of John C. Antweiler of the U.S. Geological Survey (oral commun., 1971) shows that grinding, with the techniques used for these samples, 

is unlikely to have appreciably reduced the gold particle size. 

The positive analytical results from sand-size or coarser clastic samples 

should therefore be viewed as a maximum values or perhaps only as 

qualitative indicators that a rock unit does contain gold. Conversely, 

negative analytical results can mean either that the rock unit represented by 

the sample has no gold or that the analytical split did not contain a detectable gold particle. Also, analyses of small samples containing clastic gold 

may not be comparable to analyses of small samples containing chemically 

precipitated gold, because chemically deposited gold particles probably are 

much finer and, therefore, are more likely to occur in a given analytical 

sample. 

Another possible approach to the estimation of gold abundance is 

statistical. Miesch (1967) described a method combining techniques of 
r---f\ 

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------2_1---~36-------L-------------

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1 

FIGURE 1. - Map of Northeastern United States, showing sampling areas. Number only, Paleozoic clastic rocks; circled 

number, Paleozoic and Precambrian chemical rocks; underscored number, Precambrian clastic rocks; YDP, Yellow Dog 

Plains. Locality numbers are referred to in tables 1 and 2. 

z ..., 

it! 

0 

0 

c 

(') 

..., 

~ 

Vl 
6 GOLD, SEDIMENTARY ROCKS, GREAT LAKES REGION 

Sichel (1952) and Cohen (1959, 1961) by which the mean can be efficiently 

estimated even when a large fraction of the data is in the not-detected class. 

The 36 analytical values obtained by the analysis of 799 samples plot as a 

straight line on probability paper, indicating that the data are log normal. 

The data are strongly left censored because the gold content of 95 percent of 

the samples was below the limit of detection. Cohen (1961, p. 538) tabulated 

the factor A as a function of the degree of censoring (h) and of another 

calculated quantity; however, h is tabulated between 0.01 and 0.90, and 

since h=0.954 for the data of this report, A was obtained by graph•cal nonlinear extrapolation. Because the degree of censoring is outside the range 

tabulated by Cohen, some doubt is cast on the calculated overall arithmetic 

mean gold concentration of 0.0087 ppm for the 799 samples. In addition to 

certain computational difficulties, the overall arithmetic mean gold concentration was biased by collection of additional samples from units found to 

contain relatively more gold. 

ACKNOWLEDGMENTS 

The project was conceived by Walter S. White, who together with 

Robert H. Muench and the author, planned and executed the initial sampling in 1966. Willard P. Puffett led us to some outcrops of Precambrian 

clastic rocks in Michigan. Wallace DeWitt spent 2 weeks during 1967 

sampling the Olean Conglomerate Member of the Pottsville Formation in 

Pennsylvania and New York. C. E. Brown provided locations of basal Maquoketa Shale outcrops in Iowa. The Michigan Geological Survey provided 

cuttings and a stratigraphic log of the dry James Spencer 1 oil test well. 

CLASTIC ROCKS 

PRECAMBRIAN CLASTIC ROCKS 

The sampled Precambrian clastic rocks are listed in table 1, which also 

gives the number of samples, the approximate sampling locality, and the 

results of all positive gold analyses. The sampling areas are also indicated in 

figure 1. 

Analysis of a sample of slate from the Precambrian Thomson Slate in 

Carlton, about 10 miles southwest of Duluth, Minn., showed 3.0 ppm gold, 

the highest gold concentration found in any of the samples from the Great 

Lakes region. However, three other splits of the same sample had less t~an 

0.02 ppm gold. Negative analytical results (less than 0.02 ppm) for 17 additional samples of the Thomson in the vicinity of Carlton suggest that the 

3.0-ppm value may have been a single flake of gold, either natural or a "ring 

scrape" (the outcrop is nearly vertical, next to a street, and only about 100 

yards from the Carlton High School). 

Of the 10 samples of the Marshall Hill Conglomerate collected along the 

Wisconsin River west of Brokaw, Wis., one had detectable gold (0.3 ppm). 

Gold was detected in only one (0.03 ppm gold) of the three samples of the 
CLASTIC ROCKS 

TABLE 1. - Gold content of clastic rocks of the Great Lakes region 

Wisconsin: 

Sampling 

area 

Central northern ------------

Northern-----------------

Northwestern-------------- Wisconsin and Minnesota: 

Near west end of Lake Superior. 

Minnesota: 

East central ---------------

Northeastern --------------

Michigan: 

Northern-----------------

Minnesota: 

Southeastern --------------

Wisconsin: Southwestern _____________ _ 

Illinois-IowaWisconsin. 

Wisconsin and 

Minnesota. 

Michigan: Upper peninsula ___________ _ 

Lower peninsula ___________ _ 

Ohio: 

Northern-----------------

Northeastern --------------

Locality 

(fig. I)' Formation 

Precambrian clastic rocks 

4 

12 

9 

10 

II 

II 

13 

22 

23 

24 

25 

4 

38 

17 

5 

20 

26 

6 

11 

14 

21 

28 

29 

10 

Marshall Hill 

conglomerate of 

Weidman (1917) 

(volcanic fragments 

in sericitic 

matrix). 

Keeweenawan Series 

(sandstone and 

conglomerate). 

Bayfield Group 

(sandstone). Barron Quartzite ______________ _ 

Fond duLac Sandstone 

of Winchell (1899) 

(sandstone, 

conglomerate, and 

pyritic conglomerate). 

Hinckley Sandstone------------- Thomson Slate of 

Spurr (1894). 

Puckwunge Formation 

of Winchell (1897) 

(conglomerate). 

Palms Quartzite 

(conglomerate). Jacobsville Sandstone • __________ _ 

Goodrich Quartzite ____________ _ 

Ajibik Quartzite --------------- Enchantment Lake ____________ _ 

Copper Harbor 

Conglomerate. 

Paleozoic clastic rocks 

Glenwood Shale ---------------

St. Peter Sandstone -------------

Decorah Shale ---------------- Jordan Sandstone _____________ _ 

Franconia Sandstone 

("greensand" and 

very glauconitic 

sandstone). 

Franconia Sandstone 

(slightly glauconitic 

sandstone). 

Dresbach Group --------------- Maquoketa Shale 

(shale). 

St. Lawrence Formation 

(dolomite). 

Munising Sandstone ____________ _ 

Antrim Shale 

(black shale). Ellsworth Shale _______________ _ 

Marshall Formation (sandstone). 

Napolean Sandstone 

Member of Marshall 

Formation. 

Parma Sandstone -------------- Clinton Formation 

(shale). 

Chagrin Shale ---------------- Ohio Shale 

(black shale). 

Sunbury Shale (black shale). 

Sharon Member of 

Pottsville 

Formation 

(conglomerate). 

Berea Sandstone ---------------

Number of 

samples 

analyzed 

10 

14 

12 

19 

12 

18 

II 

16 

4 

2 

1 

6 

30 

16 

14 

25 

14 

2 

7 

Gold content 

(ppm) of 

individual 

samples' 

'0.3 

.03 

.05 

3.0(?) 

0.027, O.o3, 

O.o2, 0.04, 

0.04 

.I 

.027 

.02 
8 GOLD, SEDIMENTARY ROCKS, GREAT LAKES REGION 

TABLE 1 - Gold content of clastic rocks of the Great Lakes region - Continued 

Pennsylvania: 

Sampling 

area 

Northwestern--------------

Pennsylvania and 

New York. 

New York: 

Southwestern 

Southeastern ------------ Northern ____ ----------

Virginia: 

Northern 

Kentucky: 

Western---------------

Missouri: 

Central eastern -------- __ _ 

Locality 

(fig. I)' Formation 

Paieozoic clastic rocks - Continued 

12 

13 

16 

19 

15 

18 

I 

7 

30 

31 

32 

33 

34 

35 

36 

37 

Shenango Formation 

(sandstone). 

Le BoeufConglomerate 

Member of Tesmer 

( 1958) of Cattaraugus 

Formation. 

Amity Shale of Chadwick (1925). Olean Conglomerate 

Member of Pottsville 

Formation. 

Panama Conglomerate 

Lentil of 

Cattaraugus 

Formation. 

Corry Sandstone---------------

Poughquag Quartzite ------------

Potsdam Sandstone -------------

Weverton Quartzite -------------

Chattanooga Shale 

(black shale). 

Caseyville Formation 

(conglomerate). 

Palestine Sandstone-------------

Tar Springs Sandstone ----------- Hardinsburg Sandstone __________ _ Cypress Sandstone _____________ _ 

Bethel Sandstone ______________ _ 

Bushberg Sandstone Member of Sulphur· 

Springs Formation. 

Number of 

samples 

analyzed 

4 

109 

3 

I Ill 

Gold content 

i~Jiril~!l samples' 

0.2,0.2, 

0.06 

0.0.(0:02, 

O.Q2,0.04 

'Single locality numbers usually refer to areas, not a spec?ific site; multiple numbers outline larger sampling areas. 

'Individual positive analytical results in excess of lower hmit of detection: 0.02 ppm for the 97 percent of samples analyzed 

by solvent extraction-atomic absorption method and 0.025 ppm for the 3 percent of samples analyzed by fire assay-atomic 

absor!llion bead method. Dashes indicate lack of detectable gold. 

'Of the 10 samples analyzed, I had 0.3 ppm Au, 9 had less than 0.02 ppm Au. 

•Since preparation of this report Jacobsville ·is considered to be of Cambrian and (or) Precambrian age. 

Precambrian Z Fond du Lac Sandstone collected on the Snake River near 

Woodland, Minn., and in one (0.05 ppm gold) of the eight samples from the 

basal Fond du Lac in Jay Cooke State Park (Morey, 1967, p. 2) near 

Duluth, Minn. 

PALEOZOIC CLASTIC ROCKS 

From the Paleozoic clastic rocks 403 samples were collected from 37 formations in Minnesota, Wisconsin, Michigan, Pennsylvania, New York, 

Iowa, Illinois, Missouri, Virginia, and Kentucky. Rock types sampled were 

sandstone, glauconitic sandstone, shale, conglomeratic sandstone, siltstone, 

and pyritic shale. Of the 403 samples, 15 contained detectable gold. The formations sampled, the sampling areas, number of samples analyzed for gold, 

and the analytical results are presented in table I. Figure I shows sampling 

areas for each unit. 

Of the Ill Potsdam Sandstone samples analyzed, 4 samples (2 conglomeratic and 2 nonconglomeratic) had at least 0.02 ppm gold. Only 8.5 

percent of the analyzed Potsdam samples were conglomeratic, so the conglomeratic portions appear to be relatively more favorable. 
CHEMICAL ROCKS 9 

Of the 14 samples analyzed from the Mount Simon Sandstone of the 

Dresbach Group in Wisconsin, 3 were conglomeratic sandstone, and only l 

of these had detectable gold. A possible correlative of the Mount Simon is 

the Chapel Rock Member (Hamblin, 1958) of the Munising Formation in 

northern Michigan (Hamblin, 1958, p. 114). From the Chapel Rock, 4 conglomerate samples and 10 sands tone samples were analyzed; 1 conglomerate sample had 0.027 ppm gold. 

In summary, 141 basal Cambrian samples were analyzed, and of these 6 

contained 0.02 ppm or more gold. Conglomeratic samples accounted for 4 

of the 6 positive results. 

Glauconitic sandstone from the Franconia Sandstone of Late Cambrian 

age in southwestern Wisconsin had more than 0.020 ppm gold in 5 of 30 

samples analyzed. A much higher proportion of samples from the Franconia contained detectable gold than samples from other nonconglomeratic 

Cambrian sandstones. 

Gold was detected in four other Paleozoic clastic samples; three were 

from the Pennsylvanian Olean Conglomerate Member of the Pottsville Formation in New York and Pennsylvania (0.060, 0.20, 0.20 ppm gold}, and 

one was from a 1.5-inch pyrite bed in the Devonian Ohio Shale in 

Cleveland, Ohio (0.02 ppm gold). However, only 2.7 percent of the Olean 

samples and 5.5 percent of the black shale samples had detectable gold. 

Neutron-activation analyses, reported by Bradbury, Hester, and Ruch 

(1970), of 38 black shale and 3 sandstone samples from Illinois were all 

negative; however, the lower limit of detection was very high, averaging 

0.184 ppm for the black shale samples and 0.063 ppm for the sandstone 

samples. 

PLEISTOCENE CLASTIC SEDIMENTS 

The sands of the Yellow Dog Plains, a kame terrace near Marquette, 

Mich. (Segerstrom, 1964, p. C126}, are locally reputed to contain appreciable gold. However, panned heavy-mineral concentrates from 32 sand 

and pebbly sand samples all contained less than 0.020 ppm gold. No gold 

colors were seen in the pan concentrates. 

Bradbury, Hester, and Ruch (1970, p. 13) reported that gold was not 

positively detected in 27 heavy-mineral concentrates from glacial sand and 

gravel deposits and associated river alluvium in Illinois. Although the actual 

presence of gold could not be confi1rmed, they stated that the highest possible concentration on the basis of their analyses would be 0.04 ppm. 

CHEMICAL ROCKS 

PRECAMBRIAN !CARBONATE ROCKS 

The Precambrian carbonate rocks consist entirely of marble and calcsilicate rocks of the Grenville Series which crop out in the Adirondack 

Mountains of northern New York. The Grenville Series consists of coarsely 

crystalline marble, local dolomitic beds, quartzites, gneisses, amphibolitic 
10 GOLD, SEDIMENTARY ROCKS, GREAT LAKES REGION 

TABLE 2. - Gold content of chemical rocks of the Great Lakes region 

Gold content Number of (ppm) of 

Sampling Locality samples individual 

area (fig. I)' Formation analyzed samples' 

Minnesota: 

Southeastern -------------- 10 Trempealeau Formation 

(limestone). 

11 Platteville Lims:stone ------------ 12 

14 Prairie du Chien Group 8 

(dolomite). Iowa: 

Central------------------ 21 Fort Dodge Gypsum of McGee (1884). Missouri: 

East-central --------------- 19 Kimmswick Limestone ----------- 2 

20 Callaway Limestone _____________ I 

Illinois-Iowa- 12 Maquoketa Shale 32 O.Q2 

Wisconsin. (basal phosphatic 

and carbonaceous 

Illinois-Iowa- 13 

rock). Galena Dolomite 15 

Minnesota. (limestone). 

Michigan: 

Eastern' ----------------- Traverse Group 

(limestone and shale). 

Dundee Limestone-------------- 2 .03 

Detroit River Group 

(anhydrite and dolomite). 

13 .02 

Bois Blanc Formation 

(dolomitic 

limestone). 

Bass Islands Dolomite ----------- I 

Salina and Niagara 

Groups (dolomite, 

halite, and shale). 

22 0.06,0.o3 

Cataract Formation (limestone and shale). 

Cincinnatian Series (limestone and shale). 

Trenton Limestone and Black River 

Upper Peninsula ------------ 15 

Group (limestone). 

Trempealeau Formation (limestone). 

Mackinac Breccia of Douglas (1839) 

(limestone and dolomite). New York: 

Northern----------------- 16 Theresa Dolomite -------------- I 

22 Grenville Series 46 0.02, O.Q2, 0.02 

(marble). 0.20, 0.10, 0.02 

0.08, 0.04, 0.04 0.02,0.02 

Kentucky: Western ----------------- 17 Fredonia Oolite Member 2 .02 

of Ste. Genevieve 

Limestone. 18 Fort Payne Formation (chert). 

'Sin¥1e locality numbers usually refer to areas, not a spe<:ific site; multiple numbers outline larger sampling areas. 'Indtvidual positive analytical results in excess of lower hmit of detection: 0.02 ppm for the 97 percent of samples analyzed 

by solvent extraction-atomic absorption method and 0.025 ppm for the 3 percent of samples analyzed by fire assay-atomic 

absorption bead method. Dashes indicate lack of detectable gold. 'From dry James Spencer I oil test well, Sanilac County. 

layers, migmatites, and granulites (Buddington, 1939, p. 11). Outcrops were 

selected that were dominantly marble, and samples were collected from the 

most carbonate-rich part of each outcrop. Of the 50 samples analyzed, 46 

were marble and 4 were more siliceous metamorphic rocks. Of the 46 marble samples analyzed, 11 contained detectable gold, in amounts that ranged 

from 0.020 to 0.20 ppm and averaged 0.052 ppm (table 2). Gold was found 

in a greater proportion of the samples from the Grenville marble than from 
SUMMARY AND CONCLUSIONS 11 

any other sample group. Grenville marble samples can be separated by area 

into northwestern Adirondack and eastern Adirondack groups (fig. 1 ). The 

northwestern group had a higher proportion of samples containing detectable gold than did the eastern group (1 of 3.7 compared to 1 of 5.3). Jones 

(1969, p. 22) found that marble has the lowest and highest gold values 

(0.0009 and 0.022 ppm) of metamorphic rocks analyzed by neutronactivation analysis. 

PALEOZOIC CHEMICAL ROCKS 

The Paleozoic chemical rocks sampled and analyzed are listed in table 2 

and located in figure 1. Some are outcrop samples; the remainder are cuttings, provided by the Michigan Geological Survey, of formations 

penetrated by the dry James Spencer 1 oil test well (loc. 1-10), Sanilac 

County, southern Michigan. 

Only chemical rocks from the James Spencer 1 had detectable gold. Gold 

concentrations in excess of 0.20 ppm were found in one sample of each of 

these units: Dundee Limestone, 0.03 ppm (finely crystalline limestone with 

shale lenses; lithologic descriptions from Michigan Geological Survey 

records); Detroit River Group, 0.02 ppm (anhydrite); Niagara and Salina 

Groups, 0.06 ppm (halite) and 0.03 ppm (limestone, brown to dark-brown, 

finely crystalline, streaks of carbonaceous material). 

A sample of the Fredonia Oolite Member of the Ste. Genevieve 

Limestone from Caldwell County (loc. 17), western Kentucky, had 0.02 

ppm gold. 

Hershey (1899) reported gold in the phosphatic, locally pyritic and (or) 

carbonaceous, "depauperate zone" at the base of the Upper Ordovician 

Maquoketa Shale near Pearl City and Eleroy in northwestern Illinois. Near 

Pearl City a shaft mentioned by Hershey is caved, and there is no 

depauperate-zone float on the surface in the vicinity of the shaft. Near 

Eleroy the basal Maquoketa was mined for paint pigment in the late 1800's 

and again in the 1930's. Carbonaceous basal Maquoketa float, probably 

from the mine, had less than 0.020 ppm gold in the 2 samples analyzed. In 

the present investigation an additional 30 samples of the basal Maquoketa 

were collected in Iowa and Illinois. Of these, 1 phosphatic sample from the 

Cooney quarry, 4 miles east of Elgin, Iowa, contained 0.020 ppm gold; 

no other samples contained detectable gold. 

SUMMARY AND CONCLUSIONS 

The sedimentary rocks of the Great Lakes region contain very little gold 

in spite of their proximity to the gold-rich Precambrian shield rocks of 

Canada. The analytical results must be evaluated qualitatively, for the most 

part, because they are strongly influenced by the particle-sparsity effect 

(Clifton and others, 1967). Analytical results based on small samples of 

clastic rocks containing near-background amounts of particulate gold are 

not representative of the gold values that might be expected in large bulk 

samples. If the analytical sample happens to have only one gold particle, the 
12 GOLD, SEDIMENTARY ROCKS, GREAT LAKES REGION 

results may be too high; if the sample has no gold particles, a likely occurrence, obviously no gold will be detected, and the results may be too low. 

The particle-sparsity effect could have been circumvented only by collection 

of large samples (about 120 kg), followed by separation and analysis of the 

heavy-mineral fraction. This procedure was quite impractical for a recon-

" naissance effort, and therefore the analytical results must be interpreted 

with much caution. 

Because of the particle-sparsity effect, a particular analytical result from 

one of the unconcentrated 10-g samples of this study, such as 0.050 ppm 

gold in a sandstone, does not mean that the unit from which this sample was 

collected has 0.050 ppm gold, but it does indicate that the unit represented 

by the sample contains some gold. The proportion of gold-containing 

samples from a particular geologic unit may indicate the relative amount of 

gold in that unit, especially if compared to units represented by samples 

with similar gold values. 

Though outcrops and units having detectable gold were resampled, more 

than 95 percent of the rock samples had less gold than the limit of detection, 

which was 0.025 ppm for 22 samples analyzed by fire assay and 0.020 ppm 

for 777 samples analyzed by solvent extraction- atomic absorption techniques. The distribution of gold values is strongly left censored (fig. 2) and 

log normal. The mean gold content is thus obviously less than the lower 

limit of detection. A statistical technique for estimating the mean of censored distributions (Miesch, 1967) such as presented by the data of this 

report was used to calculate an overall arithmetic mean gold concentration 

of 0.0087 ppm for the sampled rocks. 

Marble from the Grenville Series and sandstone from the Franconia, 

Mount Simon, and Fond du Lac Sandstones had significantly greater 

proportions of samples with detectable gold than the other formations 

sampled. Table 3 lists the rock types found to contain detectable amounts of 

gold together with the number of samples analyzed and the number and 

percentage with detectable gold. Obviously if only a few samples of a rock 

type are analyzed, as was true of the gypsum-anhydrite and halite 

TABLE 3. - Number, percentage, and mean gold content of analyzed samples with detectable 

gold by rock type 

Number of samples 

Nonglauconitic sandstone -------------- 314 

Shale --------------------------- 64 Limestone-dolomite------------------ 92 Conglomerate and conglomeratic sandstone___ 137 Halite___________________________ 8 

Gypsum-anhydrite------------------- 8 Glauconitic sandstone_________________ 30 

Marble-------------------------- 46 

Number of samples 

with detectable gold 

3 

2 

3 

9 

I 

I 

5 

II 

Percentage 

of samples 

with detectable gold 

0.96 

3.1 

3.3 

6.7 

12.5 

12.5 

16.7 

24.0 

Mean gold content 

(ppm) of samples 

with detectable gold 

O.Q31 

.020 

.027 

.Ill 

.061 

.020 

.031 

.053 
15 

14 

13 

12 

11 

en 

w 10 -' 

a... 

~ 9 <( 

en 8 u.. 

0 

a: 7 

w 

al 6 

~ 

~ 5 

4 

3 

2 ONE 3.00-ppm 

ANALYSISOL-----'~~__,~~__,~~__,~~__,~~----------~--------------'~~----------~--------------'~~--

0 

N 

0 

0 

0 

M 

0 

0 

0 

~ 

0 

0 

It) 

0 

0 

0 

~ 

0 

0 

I' 

0 

0 

0 

~ 

0 

0 

~ 

0 

8 

0 

~ 

0 

0 0 It) 0 .- N 

0 0 

GOLD, IN PARTS PER MILLION 

0 

... 

N 

0 

0 

It) 

N 

0 

FIGURE 2. - Frequency distribution of gold in analyzed sedimentary rocks from the Great Lakes region. 

g 

M 

0 

0 

M 

0 

en 

c:: 

a: 

a: 

> 

~ 

>--< 

> z 

0 

n 

0 

z 

n 

r 

c:: 

en 

0 

z 

en 

w 

-
14 GOLD, SEDIMENTARY ROCKS, GREAT LAKES REGION 

categories, a high percentage of samples with detectable gold is not particularly significant. Interestingly, however, Jones (1969, p. 22) believed 

that analyses for gold in gypsum and rock salt reported in 1897 and 1911 are 

suspiciously high (gypsum: 0.083, 0.083 ppm; rock salt: 0.097, 0.100, 0.1, 

<0.003, 0.12 ppm). Table 3 suggests that the gold in marble is finer grained 

than gold in conglomerate and conglomeratic sandstone because a greater 

percentage of the marble samples contained detectable gold but their mean 

gold content was lower. 

Positive gold analyses were obtained from a larger proportion of conglomerate and conglomeratic sandstone samples (6.7 percent) than from 

nonglauconitic sandstone samples (0.96 percent); moreover, of the samples 

with detectable gold, conglomerate and conglomeratic sandstone samples 

had a mean gold content of 0.111 ppm, whereas nonglauconitic sandstone 

samples had a mean content of only 0.031 ppm. These differences are 

probably partly of hydrodynamic origin; the currents that deposited the 

conglomerates were more competent and could carry larger flakes of gold 

than the currents that deposited the sandstone. Another factor of possible 

significance is that conglomerates are more likely to be single-cycle 

sediments than sandstones and, therefore, to have an igneous rather than a 

sedimentary source. Finally, many basal Cambrian conglomerate samples 

that were collected overlie "basement" rocks that could be gold sources, 

whereas the sandstones are stratigraphically higher, and possible primary 

gold sources to the north likely were covered at the time of sandstone 

deposition. 

There were 30 glauconitic Franconia Sandstone samples, of which 5, or 

16.7 percent, contained detectable gold, whereas there were 283 nonglauconitic sand$tone samples, of which 3, or 1.1 percent, contained detectable gold. It is very likely that nondetrital - that is, chemical- deposition 

of gold somehow related to the glauconite content of the Franconia accounts for this striking difference. Syngenetic chemical deposition in the 

limestone-dolomite, halite, and gypsum-anhydrite categories is also 

postulated to be important, although the number of positive values in each 

of these categories is very small. 

·Also, that the gold in some of the clastic rocks possibly is of chemical 

origin is suggested by the fact that the gold in the nonglauconitic sandstone 

category is less than 5 percent as large as the hydraulic equivalent size. 

However, presence of substantially more gold in the conglomerate and conglomeratic sandstone (table 3) argues against this hypothesis. It is possible 

to explain both the lack of gold and the apparently small particle size of 

gold that is present by postulating that gold, once in appreciable amounts in 

most of the rocks, was partially leached from those that did not have a 

protective chemical or physical environment. 

Less clear is the origin of the gold in the Grenville marble, which could be 

syngenetic chemical or even detrital. The gold could also be secondary and 
REFERENCES CITED 15 

related to the post-Grenville granitic igneous rocks of the Adirondack 

region. 

If an east-west late Precambrian-early Paleozoic continental divide was 

located south of most of the Canadian Shield gold deposits, then the 

meagerness of gold in the sedimentary rocks of the Great Lakes region most 

likely is the result of paleogeographic factors, and if fossil placers derived 

from Canadian· Shield gold deposits are to be found, they would be in the 

basal Paleozoic rocks of the James Bay region. However, if the divide was 

north of these gold deposits - the assumption made at the start of the 

search for fossil placers - then one must conclude that syngenetic processes 

of undetermined nature have concentrated anomalous amounts of gold in 

rocks of chemical or biochemical origin, and that even in a region relatively 

close to a gold source, these chemical processes are more effective concentrators of gold than the physical processes that are expected to form fossil 

placers. 

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Chadwick, G. H., 1925, Chagrin formation of Ohio: Geol. Soc. America Bull., 36, p. 455-464. 

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16 GOLD, SEDIMENTARY ROCKS, GREAT LAKES REGION 

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