Sunday, August 23, 2015

GOLD PROSPECTING FIELD TRIPS




From 1977-2007, the GemHunter led public field trips and traveled all over the country to talk to general interest and professional groups about gold, diamonds, other gemstones and geology. Many of these trips were on Hausel's personal time, others were related to work at the university. One of the last field trips to South Pass led by the GemHunter included more than 100 prospectors, rock hounds and 8 dogs on a Saturday in August.

Since Hausel no longer leads field trips, you many want to take your own trip using one of several field trip guides published by the professor. Get a free guide by visiting the GemHunter's website and click on the following PDF (Field trip guide to South Pass). You will also want to take the GemHunter's 97-page book on South Pass with you to the field.


Many of the South Pass field trips included prospectors, general public, and a few legislators who could read
 and write who outnumbered the population of all  towns in the South Pass greenstone belt (Atlantic City, Lewiston,
 Miners Delight and South Pass City). Never mind that two of the towns were only occupied by ghosts.
Figure 2. Field trip to South Pass
The South Pass greenstone belt had special meaning for the  GemHunter. "I spent 5 field seasons living in a tent  so I could map the 400 mi2 granite-greenstone belt with 3 dozen underground mines".  I could have stayed in a motel in Lander, but the Wyoming Geological Survey director was too cheap to provide much travel money - so I lived in a tent, bathed in Rock Creek, Sweetwater River (it sure wasn't sweet after I had finished bathing) and Strawberry Creek, and lived off of instant coffee and oatmeal".
On this and many field trips, the  caravan outnumbered the residents of the South Pass greenstone belt by 2:1.

Another field trip to South Pass out front of the Atlantic City Mercantile. The GemHunter at far left corner.


South Pass was Wyoming’s principal gold-bearing greenstone belt enclosing a group of gold district. Two other significant greenstone belts included the Rattlesnake Hills and Seminoe Mountains, where Hausel also discovered significant gold and started gold rushes to both areas.
The GemHunter talks to group at South Pass.
During the South Pass mapping project, Hausel (a.k.a GemHunter) identified hundreds of gold anomalies and identified previously unknown iron resources. The project resulted in mapping and sampling of several gold-bearing structures that potentially host some very large gold deposits – by far the best of these, based on sampling and mapping, is the Carissa Mine near South Pass City which was subsequently withdrawn by the State of Wyoming and turned into a circus that now attracts a couple of visitors every year. 



The GemHunter to the right looks at camera while his field trip attendees
listen to a history lecture at South Pass city.
HISTORY
According to historical records, the discovery of gold at South Pass was made on Strawberry Creek in the Lewiston area as early as 1842 by a trapper with the American Fur Company. Several years later (in 1855), a group of 40 prospectors entered South Pass to follow up on the discovery and reported finding gold nearly everywhere. This expedition was followed by a group of 9 prospectors who returned to the area in 1858 and commenced mining on Strawberry Creek. The decayed remains of their sluices were reportedly found in 1870.

Welcome to Atlantic City (photo by Sharon Hall).
In 1861, another expedition to South Pass included a group of 52 prospectors who began mining on Willow Creek, when they were attacked by Indians and driven out. Two years later (1863), gold was discovered on the Oregon Trail south of exposed greenstone belt  in the vicinity of Oregon Buttes. (Author’s note: Oregon Buttes was studied more than a century later by the US Geological Survey, and is now recognized as one of the largest undeveloped gold occurrences in North America). 

In June 1867, the richest lode in the district was discovered and named the Carissa. These miners were attacked by Indians, three were killed and the rest were driven out, but returned later in late July. In the winter of that year, more than 400 ounces of gold were recovered from the lode using primitive tools. Four tons of the ore shipped to Springfield, Utah yielded an incredible 1,400 ounces of gold!

Oregon Buttes seen in the distance from South Pass. This area includes a giant gold paleoplacer and reworked
 placers. The paleoplacer (the ridge in the lighted area in the background below Oregon Buttes) was suggested by the US
 Geological Survey to host upwards to 28.5 million ounces of gold, making it one of the largest undeveloped gold deposits
 in North America, about three-quarters the size of the giant Donlin Creek Alaska deposit. The source of the gold for 
Oregon Buttes has not been identified but in all probability is part of the buried South Pass greenstone belt at depth
 beneath the sedimentary cover near the buttes (photo by W. Dan Hausel).




Because of the continual hostilities between the Whites and Indians, the US Army established Camp Stambaugh near the towns of Atlantic City and Miners Delight in 1870. However, many recruits deserted the Army to search for gold.

The Carissa was Wyoming’s principal gold mine and produced more than 180,000 ounces of gold based on 
incomplete production records. Missing production records over a period of several years suggest that the gold production
 could have been considerably more. Mapping by the GemHunter and drilling by various companies indicates that a
 sizable gold resource remains unmined. However, the mine was recently incorporated into the South Pass City historic
 site, and possibly will never be mined again. The unmanned deposit potentially includes more than a million ounces and 
possibly several million ounces.
By 1872, 12-stamp mills were operating in the district. In 1878, the Army abandoned Camp Stambaugh. Even so, things were still not safe: the Oregon Trail had to be abandoned for a safer route to the south due to increased hostilities. South Pass continued to be a battle ground until 1882 following the signing of the Treaty of Five Nations that would eventually lead to the development of Casinos.

In 1884, placer operations were proposed, and the Granier ditch was constructed to haul water from Christina Lake (12 miles away) to South Pass. Start up of the hydraulic operation did not occur until 1890. In 1891, 6,720 ounces were recovered from the operation. Today, scattered and sporadic ma and pa prospecting operations produce some gold. However, South Pass hosts significant hidden and exposed gold deposits – nearly all are unevaluated. For example, the shear zone structure at the Carissa Mine was shown by Hausel to potentially host a very sizable gold deposit based on geology and limited sampling. 
The Carissa shear zone (photo by W. Dan Hausel). The Carissa mine was developed on an intensely folded and
 faulted structure known as a shear zone. The primary shear containing high-grade gold is 1.5 to 80 feet wide. This high-
grade ore shoot is enclosed within a major shear envelope identified by Hausel to be mineralized over a width of as much
 as 1000 feet!!! This envelope is almost completely untested even though samples show potential for a major open-pitable
 and underground gold deposit!  A 97-foot composite chip sample taken on the south side of the high-grade shear yielded
 0.023 ounces per ton. Another 30-foot sample taken on the north side of the high-grade shear yielded 0.07 ounces per ton
 of gold!  Thus the remainder of this envelope (about 850 to 900 feet) remains untested! Look for the geologist in the
 photo.



The Carissa ore deposit is structurally controlled and appears to represent a saddle reef deposit where high-grade gold is localized in fold closures and rehealed fractures similar to the Homestake mine in South Dakota (Hausel and Hausel, 2011). Geological evidence also supports that the Carissa ore body continues to depth. Support for the presence of a major ore deposit includes drilling that tested the mineralized shear below the mine workings. Drilling by Consolidated McKinney Resources identified a highly anomalous zone that was up to 80-feet-wide. Assays of drill core from this zone ranged from 0.03 to 2.54 ounces per ton gold (the shear envelop was not tested). This mineralized structure was intersected at depths up to 930 feet. In addition, Carissa Gold Inc. made the following reserve estimates on the property using an extraordinary high reserve cutoff grade. They reported 208,000 tons of ore that had an average grade of 0.343 ounces per ton and a geological reserve of 37,000 tons of ore averaging 0.85 ounces per ton!

And if you think Atlantic City is big.
Anaconda Minerals also drilled the property and all of their reported drill holes interested ore grade material: they intersected a high grade zone over widths of 2.3 to 16.1 feet that yielded 0.11 to 0.36 ounces per ton gold at depths up to 700 feet. There are many unknowns about this mine, but it is clear the Carissa is a viable exploration target that could potentially host a very sizable, untapped gold deposit! It is sad that the Wyoming Legislature purchased this property and withdrew it from mining without even seeking input by the Wyoming Geological Survey!

GREENSTONE BELT GEOCHRONOLOGY
The attendees of various South Pass field trips learned that the region is a fragment of a much larger greenstone belt Greenstone belts are found at a number of places worldwide including Canada, Australia, and Africa where a very large percentage of the world’s gold is produced. The term greenstone belt is often considered to be synonymous with the phrase Gold Belt. This is because most greenstone belts are important sources for significant amounts of gold as well as other metals including iron and nickel, and gold anomalies have been detected over very large areas of the South Pass greenstone belt. In particular in a distinct belt running from South Pass City, through the Carissa mine, through Atlantic City and to the Miners Delight mine over a belt of more than 6 miles in length. 
Schematic geological map of the South Pass greenstone belt generalized from Hausel (1991).






Several mines along this belt contain anomalous gold. The Duncan, Mary Ellen, Tabor Grand, St. Louis, and Diana are some of the better known mineralized properties and mines. Common specimens containing visible gold attest to their potential.

Miners Delight mine (Photo by W. Dan Hausel). This mine was developed on a 3 to 16 foot wide shear zone that
 has been traced over 2500 feet on the surface. Gravels in Spring Gulch draining this shear zone produced 1500 ounces of
 gold including several 1 & 2 ounce nuggets, a 6 oz nugget, and a sample of auriferous quartz described as “the size
 of a water bucket that was filled with gold”.  Samples collected across the shear zone by the WSGS ranged from 0.01 to
 0.36 ounce per ton gold.  A historic prospectus reported that there were 2,400 feet of drifts accessed from a 250 foot deep
 shaft and that the mine produced 60,000 ounces and that the gold tenor ranged from 0.3 to 110 ounces per ton of gold.
All drainages downstream from this belt have produced placer gold. Another parallel belt (about 4 miles in length) occurs in the Lewiston area. During mapping of the greenstone belt, the GemHunter also noted significant alteration that is characteristic of gold mineralization in the Crows Nest area between these two mineralized belts. In addition, the greenstone belt continues under younger rock to the northeast as well 6 miles to the south of South Pass City. It is notable that both regions where the belt continues under younger sediments are overlain by giant gold paleoplacers (McGraw Flats-Twin Creek to the north, and Oregon Buttes to the south) suggesting the presence of at least two major hidden gold deposits. To the south, Hecla Mining had found specimens of sulfide-bearing iron formation with visible gold in detrital rock. Geophysical surveys in the region identified an IP anomaly associated with a magnetic high suggesting the presence of a buried sulfide rich iron formation similar to that seen at the Atlantic City iron ore mine (Phil Howland, pers. communication). Unfortunately, Hecla pulled the plug on the project a short time later. Of the core samples that the GemHunter was asked to examine for the company, the chemistry of the metabasalts were typical of the Roundtop Mountain Greenstone Formation indicating that they were near their target of searching for banded iron formation within the underlying Goldman Meadows Formation.

View of the Duncan mine and mill.  Significant gold was detected enclosed in a distinct
 fold at this mine by the GemHunter. A 2.5 channel sample yielded 0.96 ounce per ton gold!
The rocks at South Pass are old!  South Pass is an Archean (>2.5 billion years old) greenstone belt. Gneiss in the early crystalline complex of the Wind River Mountains yields Rb-Sr dates of 2.8-3.8 Ga (billion years old), and granitic rocks of the Louis Lake Batholith (which intrude the greenstone belt) yield dates of 2.6 Ga. A Rb-Sr isochron for the Miners Delight Formation within the greenstone belt yielded a 2.8 Ga date. This latter age may represent a prograde metamorphic event, and the rocks could be older. One model lead date from the Snowbird vein at the Snowbird mine of 2.8 Ga, may suggest a temporal connection between metamorphism and mineralization.

STRATIGRAPHY OF THE GREENSTONE BELT
Mapping showed that only a portion of the South Pass greenstone belt synform is preserved at the surface. Geophysical exploration and drilling by Hecla mining to the south supported that the greenstone belt continues under young sedimentary rocks to the south for at least 6 miles.

At the base of the South Pass synform (basin) gneiss referred to as an S-type gneiss complex, or the basement of South Pass, is interleaved with the Diamond Springs Formation, the oldest member of the South Pass greenstone belt. The Diamond Springs Formation consists primarily of primitive metamorphosed igneous rocks that include distinct peridotites with MgO contents ranging from 18 to 38%; chromium from 600-10,000 ppm (parts per million); and nickel from 160-2600 ppm.  The CaO/Al2O3 ratios for these rocks are low (0.06-2.8) and they posses flat REE (rare earth element) patterns similar to komatiites. Thus these rocks are thought to represent primitive mafic and ultramafic basalts and komatiites (in other words, very high magnesium volcanic rocks).

A pot of gold at the end
of the rainbow at the Duncan mine
(photo by W. Dan Hausel).
The Goldman Meadows Formation overlies the Diamond Springs Formation. These rocks include thick banded iron formations along with mica schists and quartzite. The average iron content for the iron formations is upwards to 40%, and a sizeable resource is still present. In the past, US Steel Corporation operated a large open pit mine (Atlantic City mine) and recovered more than 90 million tons of iron ore prior to the closing of the mine in 1983.  Even so, mapping suggests that at least 300 to 400 million tons of iron ore remain in place. The geology of the Goldman Meadows formation suggests that it was deposited in shallow water on a stable platform and was shed from a nearby shelf.

The Goldman Meadows Formation is overlain by the Roundtop Mountain Greenstone. The Roundtop Mountain Greenstone consists primarily of thoeiitic oceanic basalts that in places have well preserved pillow structures. One of the more popular stops on the South Pass field trips is overlooking the iron ore mine where some excellent pillow basalts are preserved under the power line. 

The Roundtop Mountain Greenstone is overlain by the Miners Delight Formation, which is estimated to be 5,000 to 20,000 feet thick. Determination of the thickness of this unit is complicated because the entire belt has been intricately folded and faulted almost like an accordion. This formation consists primarily of metagraywacke that contains a trace to 0.051 ppm Au (gold) (compared to average of 0.002 ppm). Essentially all of the rock units at South Pass exhibit above average gold content and are interpreted to have been deposited in a moderately deep oceanic basin. However, the spatial association of proximal facies metagreywacke with meta-andesites near Miners Delight suggests that there was also a contribution from an Archean age island arc. Portions of the South Pass greenstone belt are overlain by Tertiary age, gold-bearing conglomerates in the Wasatch, White River, Arikaree, and South Pass Formations.  It is obvious that South Pass is highly anomalous in gold!

GOLD GEOCHEMISTRY
Iron Formation from South Pass showing open fold.
Banded iron formation from the former Atlantic City
iron ore mine showing many folds.
The gold geochemistry was studied by the US Geological Survey. The Au/Ag ratios are high & Au/Cu ratios are low for some of the gold at South Pass. Trace metal contents (Bi, Pb, As, Sb, V, Mo, W, B, Nb, Zn, Cr, Co, Ni) are typical of hypothermal veins in other greenstones worldwide. Stable isotopes and fluid inclusion studies support that the South Pass gold is similar to that of a hypothermal vein system. The carbon and oxygen isotopes in shear zones along with hydrogen isotopes from fluid inclusions support that the much of the gold solutions were derived from the dewatering of the Mineral Delight Formation during compaction. Others suggest that the gold was introduced but the intrusion of the Louis Lake batholith. Either way, the South Pass greenstone belt likely hosts some significant discovered (Carissa) and undiscovered gold deposits.

Structurally, the major gold systems at South Pass are located adjacent to a distinct group of metagabbos, metatholeiites, and actinolite schists (metakomatiites) that trend from South Pass City to Miners Delight. The localization of gold in this region is believed to be due to competency contrasts between the metagabbros and adjacent Miners Delight metagraywackes. During folding, it is thought that these zones provided favorable fractures and faults. Much of the ore is found in these shear structures contain enriched ore shoots developed in folds suggestive of a reef-type structural control (plunging folded gold ore shoots). Placers downstream from the shear structures are highly enriched in gold.

PLACERS
Figure 10. Visible gold in sample from the Carissa mine dump.
Some of the placers at South Pass contain significant coarse gold. For example, XL Dredging mined portions of Big Atlantic Gulch about 1910 and recovered nuggets weighing 0.07 to 1 ounce. The ET Fisher Company dredged Rock Creek from 1933 to 1941 and produced 11,000 to 30,000 ounces: 75% of the gold was within 3 feet of bedrock. Some of the gold was coarse and several nuggets were recovered. Nuggets recovered from Rock Creek include many small and some large nuggets. Boulders containing as much as 630 ounces of gold were also reported in the historical record. Much of this coarse gold was found during dredging of various drainages. 

The Fisher dredging operation was not efficient in gold recovery and it is clear that it rejected many coarse gold nuggets, as nugget hunters in the past have found more than a hundred "reported" nuggets with metal detectors searching the mined tailings. Who knows how many unreported nuggets were recovered. In addition, the plant for the dredge likely was not effective in fine gold recovery and much of that gold likely was also lost to the tailings. It was not uncommon for placer miners in the 19th and 20th centuries to ignore fine gold recovery. The placer operation continued mining gold until ordered closed at the beginning of World War II to force domestic production to focus on the war effort. Gold was not considered a strategic metal at the time. After the war, a very large portion of the commercial gold mines did not resume operations as many of the men associated with the mines had been displaced, died, or lost interest in mining. In addition, the country was rebuilding and many metal structures in these gold mines had been scrapped for the war effort. So, even though the Rock Creek mine was considered commercial, it did not resume after the war.

PALEOPLACERS
Gold from the Gerald Stout placer operation on Rock Creek at South Pass.
Gold paleoplacers (old dry placers) cover large areas at South Pass. The paleoplacers have been studied by the US Geological Survey. Isolated islands of the paleoplacer are found within the greenstone belt as well as on the edge of the greenstone belt. For example, one paleoplacer sits immediately south of Atlantic City in the South Pass Formation. This gold-bearing paleoplacer remains unevaluated.

A 7.5 ounce nugget recovered from the E.T. Fisher dredge
tailings by a prospector from Rock Springs.
At Oregon Buttes, the Wasatch Formation conglomerates are estimated to be 1300 feet thick and cover 8 mi2 and host a gold anomaly estimated to contain as much as 28.5 million ounces. Some gold-bearing oil well cuttings were recovered from depths of 6,500-7,000 feet just 0.5 mile north of the Continental Fault adjacent (north) of Oregon Buttes indicating the presence of a buried auriferous shear zone. Geophysical exploration in this area by Hecla Mining Company identified what appears to be a iron formation (at depth). Hecla interpreted this to be a gold-bearing iron formation. 

The paleoplacers at Oregon Buttes have been reworked producing some enriched dry placers. 

SUMMARY
Another field trip group at South Pass with the GemHunter
All of the field trip attendees had a good time in the sun and learned about the mining history and methods used to find gold. Many of them also became aware of the tremendous gold potential of this district and the possibilities that some mines and some high-paying jobs could result from exploration and development in this region. 

RECOMMENDED READING
Looking at the Fritag plaeoplacer near Oregon Buttes
The Gerald Stout placer operation on Rock Creek.


  • Hausel, W.D., 1989, The geology of Wyoming's precious metal lode and placer deposits: Geological Survey of Wyoming Bulletin 68, 248 p.
  • Hausel, W.D., 1991, Economic geology of the South Pass granite-greenstone belt, Wind River Mountains, western Wyoming: Geological Survey of Wyoming Report of Investigations 44, 129 p.
  • Hausel, W.D., 1993, Mining history and geology of some of Wyoming's metal and gemstone districts: Wyoming Geological Association Jubilee Anniversary Field Conference Guidebook, p. 39-63.
  • Hausel, W.D., and Hull, J., 1990, Guide to gold mineralization and Archean geology of the South Pass greenstone belt, Wind River Range, Wyoming, in Roberts, S., Geologic field trips to western Wyoming: Geological Survey of Wyoming Public Information 29, p. 178-191.
  • Hausel, W.D., 1994, Mining history of Wyoming's gold, copper, iron, and diamond districts: Mining History Association 1994 Annual, Reno, Nevada, p. 27-44.
  • Hausel, W.D., and Love, J.D., 1991, Guide to the geology and mineralization of the South Pass area, in S. Roberts, editor, Mineral Resources of Wyoming: Wyoming Geological Association 42nd Annual Field Conference Guidebook, p. 181-200.
  • Hausel, W.D., and Love, J.D., 1991, Guide to the geology and mineralization of the South Pass area: Wyoming State Geological Survey Reprint 49, 20 p.
  • Snyder, G.L., Hausel, W.D., Klein, T.L., Houston, R.S., and Graff, P.J., 1989, Precambrian rocks and mineralization, Wyoming Province: 28th International Geological Congress guide to field trip T-332, July 19-25, 48 p.
Dave Fritag shows vial filled with gold mined from the dry
alluvial placers at Oregon Gulch (photo
by W. Dan Hausel, and courtesy of Dave Fritag).
Another of many field trips to South Pass as the GemHunter (green jacket)
talks about the gold-bearing shear zones at South Pass. In addition to leading
field trips for the general public, rock hound, prospecting and history
groups and clubs, the GemHunter also led field trips for various
regional, national and international field conferences including the Wyoming
Geological Association, International Geological Congress, and more. No
other geologist in the history of the Wyoming Geological Survey had won
so many honors including the Thayer Lindsley Award for a Major
Gold Discovery (this was presented to 6 other geologists
including Hausel) , the Wyoming Geological Association's Distinguished
Service Award and many others. 

South Pass gold reports

SOUTH PASS GRANITE-GREENSTONE BELT
During the 1980s, the author completed 8 geological quadrangles covering more than 350 square miles of surface area within the South Pass region along the southern tip of the Wind River Mountains. This project resulted not only in the production of this group of geological maps, but also several underground mine maps were completed, dozens of gold anomalies were detected, and many structural controls (or guides) for gold mineralization were recognized including a few gold targets of potential size.
Much of the data was published in several reports and compiled into an overall summary on this important greenstone terrain. South Pass has historically been the state's most productive gold and iron ore district ( see Hausel, 1991, WSGS, Report of Investigations 44).
Many of the other papers published by various outside journals and conference proceedings may be available at various University libraries.
The B & H mine overlooking the South Pass Greenstone Belt, WY

REPORTS ON SOUTH PASS PREPARED BY THE WSGS
Hausel, W.D., 1980, Gold districts of Wyoming: Geological Survey of Wyoming Report of Investigations 23, 71 p.
Hausel, W.D., 1983, Field notes (and mine map) on the Gold Dollar mine, South Pass district, Wyoming: Geological Survey of Wyoming unpublished Mineral Report MR83-1, 5 p(scale 1:240)
Hausel, W.D., 1983, Field report (and mine map) on the Dream gold mine, Lewiston district, South Pass greenstone belt, Wyoming: Geological Survey of Wyoming unpublished Mineral Report MR83-2, 5 p. (scale 1:240).
Hausel, W.D., 1983, Field notes (and mine map) on the Carrie Shield gold mine, South Pass district, Wyoming: Geological Survey of Wyoming unpublished Mineral Report MR83-3, 5 p. (scale 1:240).
Hausel, W.D., 1983, Assay report on samples collected from the Lewiston, Burr, and section 33 mines, Lewiston district, South Pass: Geological Survey of Wyoming unpublished Mineral Report MR83-5, 3 p.
Hausel, W.D., 1983, Assay report on samples collected from the Caribou gold mine, South Pass district, Wyoming: Geological Survey of Wyoming unpublished Mineral Report MR83-6, 3 p.
Hausel, W.D., 1983, Report on B&H mine dump samples, South Pass district, Wyoming: Geological Survey of Wyoming unpublished Mineral Report MR83-7, 3 p.
Hausel, W.D., 1983, Field notes and assay report for the Franklin mine, South Pass district, Wyoming: Geological Survey of Wyoming unpublished Mineral Report MR83-18, 3 p.
Hausel, W.D., 1983, Geochemistry of the Exchange gold vein, South Pass greenstone belt, Fremont County, Wyoming: Geological Survey of Wyoming unpublished Mineral Report MR83-19, 14 p.
Hausel, W.D., 1984, Preliminary geologic map of the Doc Barr gold mine, South Pass: Geological Survey of Wyoming unpublished Mineral Report MR84-1, scale: 1:240.
Hausel, W.D., 1984, Geologic map of the Wilson Bar adit, South Pass, Wyoming: Geological Survey of Wyoming unpublished Mineral Report MR84-3, scale: 1:240.
Hausel, W.D., 1984, Geologic map of the Big Chief gold mine, South Pass: Geological Survey of Wyoming unpublished Mineral Report MR84-4, scale: 1:240.
Hausel, W.D., 1984, The Soules & Perkins gold mine, South Pass, Wyoming: Geological Survey of Wyoming unpublished Mineral Report MR84-6, 2 p. (scale: 1:240).
Hausel, W.D., 1984, Tour guide to the geology and mining history of the South Pass gold district, Fremont County, Wyoming: Geological Survey of Wyoming Public Information Circular 23.
Hausel, W.D., and King, J.K., 1985, Geologic map of the St. Louis mine: Geological Survey of Wyoming unpublished Mineral Report MR85-1, (scale: 1:240).
Hausel, W.D., and King, J.K., 1985, Geologic map of the Smith Gulch adit: Geological Survey of Wyoming unpublished Mineral Report MR85-2, (scale: 1:240).
Hausel, W.D., and King, J.K., 1985, Geologic map of the Big Atlantic Gulch adit: Geological Survey of Wyoming unpublished Mineral Report MR85-3, (scale: 1:240).
Hausel, W.D., and King, J.K., 1985, Geologic map of the Old Hermit mine, South Pass-Atlantic City district: Geological Survey of Wyoming unpublished Mineral Report MR85-4, (scale: 1:240).
Hausel, W.D., and Gyorvary, Steve, 1985, Geologic map of the Tornado mine, South Pass-Atlantic City district: Geological Survey of Wyoming unpublished Mineral Report MR85-5, (scale: 1:240).
Hausel, W.D., 1985, Geology and gold mineralization of the South Pass granite-greenstone terrain, western Wyoming: Utah Geological Association 1985 Guidebook, p. 183-192.
Hausel, W.D., 1985, Structural and stratigraphic control of Archean gold mineralization within the South Pass greenstone terrain, Wyoming [abstract]: The Contact, Wyoming Geological Association, v. 31, no. 12, p. 1-2.
Hausel, W.D., 1985, Road log to South Pass geology: International Archean Geochemistry Field Conference, August 12, 12 p.
Hausel, W.D., 1986, Preliminary report on the geology and gold mineralization of the South Pass granite-greenstone terrain, Wind River Mountains, western Wyoming (USA), in Workshop on the Tectonic Evolution of Greenstone Belts: Lunar and Planetary Institute, Houston, Texas, p. 114-115.
Hausel, W.D., 1986, Preliminary report on the geology and gold mineralization of the South Pass greenstone belt, Wind River Mountains, Wyoming: Society of Mining Engineers of AIME Preprint 86-15, 10 p.
Hausel, W.D., 1986, Geologic map of the Lewiston gold district, Radium Springs Quadrangle, Fremont County, Wyoming: Geological Survey of Wyoming Open File Report 86-25 (scale 1:24,000).
Hausel, W.D., 1986, Geologic map of the Anderson Ridge Quadrangle, Fremont County, Wyoming: Geological Survey of Wyoming Open File Report 86-26 (scale 1:24,000).
Graff, P.J. , and Hausel, W.D., 1986, Gold from Wyoming greenstone belts - production and prognostications, in Roberts, S., editor, Metallic and Nonmetallic Deposits of Wyoming and Adjacent Areas, 1983 Conference Proceedings: Geological Survey of Wyoming Public Information Circular 25, p.13-21.
Hausel, W.D., 1987, Preliminary report on the gold mineralization, petrology, and geochemistry of the South Pass granite-greenstone belt, Wind River Mountains, Wyoming: Wyoming Geological Association 38th Annual Field Conference Guidebook, p. 287-304.
Hausel, W.D., 1987, Structural control of Archean gold mineralization within the South Pass greenstone terrain, Wyoming (USA), in The Practical Applications of Trace Elements and Isotopes to Environmental Biogeochemistry and Mineral Resources Evaluation, Theophrastus Publications, Athens, Greece, p.199-216.
Hausel, W.D., 1987, Structural control of gold deposits in the South Pass granite-greenstone belt, Wind River Mountains, Wyoming, in North American Conference on Tectonic Control of Ore Deposits Proceedings, University of Missouri-Rolla, p. 160-165.
Hausel, W.D., 1987, Revised geologic map of the Miners Delight Quadrangle, Fremont County, Wyoming: Geological Survey of Wyoming Open File Report 87-10 (scale 1:24,000).
Hausel, W.D., 1988, Revised geologic map of the South Pass City Quadrangle, Fremont County, Wyoming: Geological Survey of Wyoming Open File Report 88-2 (scale 1:24,000).
Hausel, W.D., 1988, Preliminary geologic map of the Lewiston Lakes Quadrangle, Fremont County, Wyoming: Geological Survey of Wyoming Open File Report 88-3 (scale 1:24,000).
Hausel, W.D., 1988, Revised geologic map of the Atlantic City Quadrangle, Fremont County, Wyoming: Geological Survey of Wyoming Open-File Report 88-7 (scale 1:24,000).
Hausel, W.D., 1988, Reconnaissance geologic map of the Halls Meadow Springs Quadrangle, Fremont and Sublette Counties, Wyoming: Geological Survey of Wyoming Open-File Report 88-8 (scale 1:24,000).
Hausel, W.D., 1988, Revised geologic map of the Louis Lake Quadrangle, Fremont County, Wyoming: Geological Survey of Wyoming Open-File Report 88-12 (scale 1:24,000).
Hausel, W.D., 1988, Geologic map of the Radium Springs Quadrangle, including the Lewiston gold district, Fremont County, Wyoming: Geological Survey of Wyoming Map Series 26 (scale 1:24,000).
Hausel, W.D., 1988, Wyoming - a frontier for gold exploration: The Mining Claim, Wyoming Mining Association, v. 13, no. 3, p. 10-11.
Hausel, W.D., 1988, Gold in Wyoming, in Modreski, P.J., editor, Mineralogy of precious metal deposits - a symposium on the mineralogy of gold and silver deposits in Colorado and other areas: Colorado Chapter, Friends of Mineralogy - Department of Geology, Colorado School of Mines joint conference, p. 122-124.
Hausel, W.D., 1988, The geology of Wyoming's precious metal lode and placer deposits (abstract): The Contact, Wyoming Geological Association, vol. 34, no. 3, p. 3.
Hausel, W.D., 1989, The Geology of Wyoming’s Precious Metal Lode and Placer Deposits: Wyoming State Geological Survey Bulletin 68, 248 p.
Day, W. C., Hill, R.H., Kulik, D.M., Scott, D.C., and Hausel, W.D., 1989, Mineral resources of the Sweetwater Canyon wilderness study area, Fremont County, Wyoming: U.S. Geological Survey Bulletin 1757-D, 22 p.
Snyder, G.L., Hausel, W.D., Klein, T.L., Houston, R.S., and Graff, P.J., 1989, Precambrian rocks and mineralization, Wyoming Province: 28th International Geological Congress guide to field trip T-332, July 19-25, 48 p.
Hausel, W.D., 1989, Revised geologic map of the Atlantic City quadrangle, Fremont County, Wyoming: Geological Survey of Wyoming Map Series MS-28 (scale 1:24,000).
Hausel, W.D., 1989, Structural control of Wyoming gold deposits [abstract]: The Contact Newsletter, Wyoming Geological Association, v. 35, no. 10, p. 2.
Hausel, W.D., 1990, Archean gold mineralization within the South Pass greenstone terrain, Wyoming in Hollister, V.T., editor, Case histories of gold deposits, Volume 2, Discoveries of valuable minerals and precious metals deposits related to intrusions and faults: Society for Mining, Metallurgy, and Exploration, Inc., Littleton, Colorado, p. 361-373.
Hausel, W.D., 1990, Geologic map of the South Pass granite-greenstone belt, southern Wind River Range, western Wyoming: Geological Survey of Wyoming, Report of Investigations 44-plate 1, scale 1:48,000.
Hausel, W.D., and Hull, J., 1990, Guide to gold mineralization and Archean geology of the South Pass greenstone belt, Wind River Range, Wyoming, in Roberts, S., Geologic field trips to western Wyoming: Geological Survey of Wyoming Public Information 29, p. 178-191.
Hausel, W.D., 1990, Precious metal deposits of Wyoming, in D.M. Hausen, editor, Gold '90: Society of Mining, Metallurgy, and Exploration of AIME, Littleton, CO. p. 53-63.
Hausel, W.D., 1991, Precious and base metal deposits of Wyoming: Northwestern Mining Association Convention Paper 21, 19 p.
Hausel, W.D., 1991, Economic geology of the South Pass granite-greenstone belt, Wind River Mountains, western Wyoming: Geological Survey of Wyoming Report of Investigations 44, 129 p.
Hausel, W.D., 1991, The form, distribution, and geology of gold, platinum, palladium, and silver deposits in Wyoming: Colorado Mining Association National Western Mining Convention Paper, Denver, CO., 18 p.
Hausel, W.D., Edwards, B.E., and Graff, P.J., 1991, Geology and mineralization of the Wyoming Province: Society for Mining, Metallurgy, and Exploration of AIME, Littleton, CO., Preprint 91-72, 12 p.
Hausel, W.D., and Love, J.D., 1991, Guide to the geology and mineralization of the South Pass area, in S. Roberts, editor, Mineral Resources of Wyoming: Wyoming Geological Association 42nd Annual Field Conference Guidebook, p. 181-200.
Hausel, W.D., and Love, J.D., 1991, Guide to the geology and mineralization of the South Pass area: Wyoming State Geological Survey Reprint 49, 20 p.
Hausel, W.D., 1992, Revised geologic map of the Miners Delight quadrangle, Fremont County, Wyoming: Geological Survey of Wyoming Map Series MS-38, (scale 1:24,000).
Hausel, W.D., 1993, Gold mineralization in the Archean Wyoming Province, USA [abstract]: Gold Society of China International Symposium on Gold, Beijing, 2 p.
Hausel, W.D., 1997, The geology of Wyoming's copper, lead, zinc, molybdenum, and associated metal deposits in Wyoming: Geological Survey of Wyoming Bulletin 70, 224 p.
Hausel, W.D., 1999, The Carissa Gold Mine, South Pass, Wyoming – A sleeper?: International California Mining Journal, v.68, no. 11, p. 14-16.
Hausel, W.D., 2001, The South Pass gold placers, western Wyoming: International California Mining Journal, v.70, no. 8, p. 29-35 & 41-42.
Hausel, W.D., 2001, Placer and Lode Gold Deposits: International California Mining Journal, v. 71, no. 2, p. 7-34.

Hausel, W.D., 2002, Searching for gold in Wyoming: Wyoming State Geological Survey Information Pamphlet 9, 12 p.
Hausel, W.D., and Hausel, E.J., 2011, Gold - Field Guide for Prospectors & Geologists, GemHunter Publications, 366 p.

Wednesday, September 25, 2013

Thar's Gold In Them Thar Hills

South Pass was a place I loved and a place where I figured I would retire. The only problem was traffic congestion; but with practice, one can get around that problem. It's the kind of place that if there were any ducks in the area, members of the Robertson clan would also live there.

Over three decades, I led dozens of field trips to South Pass and other gold districts around Wyoming to educate the public on prospecting. But from 2004 to 2007, the Wyoming Geological Survey, was operated by - well how do you say ....? Ah, I know, a complete moron. I take off my hat to the university hiring him without a background check.

Back to better things - South Pass was Wyoming's first gold discovery. Most of the greenstone belt and its gold districts remained poorly explored. When I started at the Geological Survey, I heard some claim the region was mined out. This is what most people and nearly every historian who knows nothing about geology claim about mining districts. When I decided to map the district in the 1980s, much of the region was unmapped and there was practically no information on any of the mines. It had been overlooked just like the Seminoe Mountains greenstone belt where I found visible gold and started a gold rush in 1981 and also the Rattlesnake Hills greenstone belt, where the geology was so favorable for large gold deposits, I couldn't believe no one had ever looked for major disseminated and high-grade gold deposits. Anyone who has studied gold deposits should have been in these three areas.

So, is South Pass finally mined out? Not even close! Since I investigated the district in the 1980s and published my book on the district in 1991, only a small amount of gold has been taken out. But get this - the Carissa gold mine, was only partially mined when the Wyoming State Legislature in the wisdom that can only be described as political, under-the-table, wisdom, decided to buy the mine from a private owner and place it in their South Pass City historical state park - a park that generates a few $hundred (maybe a few $thousand in some years) for the general fund. Yet, the Carissa still had gold. It had gold at the surface, enormous parts of its shear zone (the structure that contains the gold) remained unmined and unexplored, and it also had high-grade gold intercepts at depth beneath the mine workings. The geology of this mine (and nearly all mines in the district) is such that the gold is focused in steeply plunging ore shoots in shear zones. These shoots don't normally just give out. Similar shoots in other greenstone belts in Australia and Canada have produced gold to depths of 5000 or more feet. The Carissa shaft was only 400 feet deep. So, how many millions of ounces did the State of Wyoming take away from its citizens by withdrawing this mine?

Come to think of it, I have a start on my beard and
hair (actually I had long hair all though HS and college)
so maybe I could be an honorary Robinson (Duck Dynasty)
cousin. And I also like Duct tape, so maybe there's a
possibility I'm also related to Uncle Red?
And then there are the gold-bearing shear zones in the Atlantic City-South Pass City- Miners Delight trends and also in the Lewiston trend. These trends contain numerous historical mines and prospects, but more than 95% of the structures have never been sampled! Who knows what gold mine awaits discovery along these trends.

And then there are the giant gold paleoplacers - where gold is found in giant alluvial fans and reworked fans that were eroded from the South Pass area, or from a giant, hidden lode adjacent to the paleoplacers. The USGS suggested that just one of these - the Dickie Springs-Oregon Buttes paleoplacer contained at least 28.5 million ounces of gold. Where did all of the gold come from? I'm pretty sure I know, but it remains unexplored and buried.


Another unforgettable field trip to South Pass. The1989 International Geological Congress field trip to the Wyoming
 Craton which included South Pass.The lady was the Minnesota State Geologist. I'm the good looking guy second from the
 right. The other three guys were Russian geologists - one was a KGB agent (for those of you who did not grow up during
the cold war, this is the same as a Democrat) who kept all of the money and everything else for the other Russian members
 (yep, sounds like Obamacare). Anytime the Russian geologists needed money for coffee etc, they had to go to the KGB
 agent and beg for money. 



2002 photo of another field trip to South Pass (photo by Dave Miller, 2002). I'm in the center talking about geology.


Field trip for gold panning




Field trip to Snowy Range, Wyoming


Paleoplacer gold from the Dickie Springs area (photo courtesy of J. David Love).

Gold-bearing fanglomerate at Dickie Springs south of South Pass.



Friday, June 1, 2012

The Carissa Gold Mine in the South Pass greenstone belt

Gold was initially reported in the Wyoming Territory in 1842 by a fur trapper from the American Fur Company who had been working a trap line along the Sweetwater River near the Wind River Mountains. The location of this discovery may have been along Strawberry Creek, a tributary of the Sweetwater River located near the eastern edge of the South Pass greenstone belt. South Pass lies south of the town of Lander.



Mineralized terrains in Wyoming modified from Hausel (1997). The South Pass
greenstone belt lies in western Wyoming at the southern tip of the Wind River Mountains.
The initial gold discovery was in Strawberry Creek near the eastern edge of the greenstone belt.

Greenstone belts form geological (structural) basins filled with primitive volcanic flows and sediments that were intruded by dikes, sills and stocks and deposited along the margins of ancient proto-continents. These were later deformed and metamorphosed. To many geologists and prospectors, ‘greenstone belts’ are synonymous with ‘gold belts’ since they provide excellent places to search for gold. Such basins are typically >2 billion years old: the majority of rocks in the South Pass greenstone belt were metamorphosed >2.8 billion years and were likely deposited 3+ billion years ago. Some of the more notable greenstone belts in the world are located in the Slave and Abitibi regions of Canada, the Pilbara and Yilgarn regions in Western Australia, and the Kaapvaal and Barberton regions of Africa – all are well known for significant gold deposits.
7.5 ounce nugget recently found in tributary of Rock Creek
Essentially all rocks in greenstone belts have slightly higher than normal gold content. Those in the South Pass greenstone belt typically average 2 to 10 times the amount of gold as average crustal abundance, thus these provided an excellent source for gold deposits that likely formed during regional metamorphism and deformation (Hausel, 1991).

When circumstances are right, greenstone belts provide good source beds for lode gold. What is required is hot metamorphic fluids to migrate through the basins and leach enough rock and then focusing the gold-bearing hydrothermal fluids in faults, veins or similar traps to produce ore shoots (enriched pockets) of gold. This happened in several greenstone belts around the world simply because mother earth was brutal to these basins but she provided several opportunities to leach gold from the layered rocks and focus the gold into traps. Such traps include fractures, intersecting fractures and veins, shear zones, stockworks, fold closures and chemically reactive rocks. For the most part, fractures, or zones of lower pressure, were ideal for gold-bearing fluids that were squeezed from the adjacent ductile rocks under great pressure and temperature.

A tight fold in mica-rich quartzite (meta-graywacke) at South Pass.
The knife sits along a fracture. The rock above this fracture
has graded bedding – coarser sand grains that decrease in size 
towards the top similar to what is found in modern streams. This 
tells geologists that the top of this rock was towards the top of the photo 
3 billion years ago. Below this fracture we have contradictory
evidence. Cross beds, (also found in modern streams), typically are cut (terminate)
by stream action. The small cross bed at the  bottom indicates the top of this part
of the outcrop was in the opposite direction as the graded beds. The only explanation
is the fracture represents a fold axis and the outcrop below & above the fracture was
 at one time facing in the same direction until folded along a very tight (isoclinal) fold.
The nose of the fold lies either somewhere at depth in the rock outcrop perpendicular
to the fracture, or lies somewhere in space and long since been removed by erosion.

To see how this works, take your hands, place them in front of you. Now touch your finger tips together. The top of each hand would represent the top of the rock unit when it was deposited. Now let your finger tips act as a hinge and bring your palms together: the top of your right hand should be in the opposite direction as your left hand.
A 34-ounce nugget found in the Rock Creek drainage during
dredging prior to World War II. Specimen from the Los
Angeles Museum
All greenstone belts exhibit many very tight folds, many faults, fractures, and shear zones as a result of the tectonic processes that crushed and mangled these regions over eons of time. In places, greenstone belts are almost like accordions because of the many folds stacked on top of one another. Often, it is difficult to tell which rocks are right side up and which are overturned. So intense is the deformation that we can actually map rock sitting right side up adjacent to rock that is completely overturned within inches of one another. To complicate matters further, these belts are often intruded along their margins by large granite batholiths. They also inter-finger (and lie on) with much older gneissic terrains that were the basement complexes that the greenstones were deposited on. To most geologists, these belts are a nightmare to map, as the geology and geological history are very complex and never obvious. The gneissic complex for the South Pass greenstone belt was mapped along Anderson Ridge and Lewiston Lakes areas. These gneisses are undated, but may be as old as 3.5 to 3.8 billion years.

Wyoming has four greenstone belts (Elmer’s Rock, Rattlesnake Hills, Seminoe Mountains and South Pass) and one large metasedimentary belt with similarities to greenstone belts (Copper Mountain). All remained unmapped and only partially explored until the 1980s and 1990s. The author mapped all of them with the exception of Elmer’s Rock, which was mapped by Graff and others (1982). For the most part, greenstone belts are formed of dark to black rocks with some dark green rocks that are difficult to differentiate and only a handful of geologists find great joy in the challenge of unraveling these complex geological puzzles.

Dark meta-basalt folded into an isoclinal fold in which the fold is so tight that the
 fold limbs parallel one another. Below – fold in banded iron formation displaying very tight folds, almost like an accordion.


Along with complex geology, there is usually gold in many fractures, faults, veins and folds. The problem is finding where the gold has been enriched enough to produce ‘ore shoots’ that contain minable quantities of gold. Often, ore bodies in greenstone belts sit right under our noses and are consistently missed by geologists and prospectors because of the complex geology. It takes considerable detective work to figure out where ore shoots are located in lodes and how they are oriented. When the lodes are located, rich placers are almost always found immediately downstream.

In 1855, territorial records show that a group of 40 prospectors including the original fur trapper traveled back to South Pass from Georgia in search of the gold in the Sweetwater River or Strawberry Creek. The group reportedly found gold everywhere in the Sweetwater River and its tributaries. In the winter, they traveled from South Pass to a more hospitable environment at Ft Laramie to the east (a distance of 220 miles as the crow flies). For some unknown reason, they were arrested upon arrival at Ft. Laramie. Three years later in 1858, one member of this group along with 8 other prospectors ventured back to South Pass, and in 1860 commenced mining along Strawberry Creek near the site of the original discovery site.
Carissa mine shear zone show location of the
primary gold shear that averages 0.15 to 0.3 opt Au,
a geologist for scale, and the surrounding rock for
at least 1,000 feet is also highly fractures and
mineralized. Samples in this structure yield gold
values of 0.02 to 0.07 opt Au over 300 feet, the
rest of it remains to be sampled.

In 1861, another group of prospectors began mining along Willow Creek, 15 miles west of Strawberry Creek. This group of 52 prospectors was attacked by Shoshone Indians and driven out. In 1863, another group of prospectors discovered gold in dry placers near Dickie Springs adjacent to the Oregon Buttes along the Overland trail several miles south of Willow Creek and worked the area for 3 months before being attacked by Indians. Most of the prospectors were killed. At this time in history, little could be done to provide security for prospecting groups as the nation was in the grips of civil war.

Over the next several years, hostilities between prospectors and the Shoshone intensified requiring that the Overland Trail be abandoned for a more southerly route (Hausel and Love, 1993). These kinds of hostilities were common in Wyoming and were one of many reasons why Wyoming remained relatively unprospected compared to other territories in the West. Wyoming remained a wilderness that few settlers dared to journey into. Today, instead of Indian hostilities, both the State and Federal Government bureaucrats have taken on hostilities against prospectors and miners.

Another group of prospectors entered South Pass in 1866 to mine gold in Willow Creek. In the following year, this group traced gold up Willow Creek to Carissa Gulch, which was rich in gold. From the mouth of the gulch, the precious metal was traced further up slope to the Carissa lode. Claims were filed on the lode on June 8th, 1867. Within a short time, this group of prospectors was attacked by Indians and three were killed: the surviving members fled, but returned more than a month later on July 28th. During the ensuing winter, more than 400 ounces of gold were recovered using very primitive hand tools and mortars. Four tons of high grade ore was hauled to Springville, Utah and milled yielding an astounding 1,400 ounces of gold! News of the discovery reached the outside world and a rush followed.

Generalized geological map of the South Pass-Atlantic City district (from
Hausel, 1989, 1991)

The district was initially called the Shoshone district. Then it was divided into smaller districts that included an area east of the Carissa near Rock Creek which became known as the California district. Four towns erupted along the pediment at South Pass. South Pass City boasted 5,000 citizens – most living in tents (some reports suggested as many as 10,000 people were in South Pass City). Hamilton City (Miners Delight) grew to 1,500 people and Atlantic City had 500 citizens. Pacific City in the Pacific district to the south near Oregon Buttes claimed 600 people. In 1870, the US Army established Camp Stambaugh a few miles east of Atlantic City and Hamilton City to add stability in the area. The camp was abandoned eight years later.

In 1872, the district had 12 operating stamp mills. A few years later, in 1879, another town was established east of South Pass City near the original gold discovery. This town became known as Lewiston (Lewiston, Miners Delight and Pacific City are now ghost towns). In 1884, an engineering project was initiated with the construction of the Granier Ditch. The ditch was built to haul water from Lake Christina 12 miles to the west in the high peaks of the Wind River Mountains to the South Pass area for hydraulic mining. This project was finished in 1890. In the following year, 6,720 ounces of gold were recovered at the hydraulic mine.

When I began mapping in the South Pass greenstone belt in the 1980s, I was quite impressed by the size of the belt and amazed that such an important district had remained mostly unmapped and poorly explored in modern times. Little information was available on the historical mines and mineralized zones in the district. Thus over the course of several years, I mapped 250 square miles of the complex, identified a few hundred gold anomalies, mapped all of the old mines I could get access to, and divided the greenstone belt into two separate districts based on geology: the Lewiston district along the eastern limb of the basin and the South-Pass-Atlantic City district along the western limb (Hausel, 1991). Two other districts were recognized in Tertiary and Recent sediments by the US Geological Survey that eroded from the South Pass greenstone belt. These were McGraw Flats to the north and Oregon Buttes-Dickie Springs to the south. Both contain large dry paleoplacers (fossil placers) with minor modern placers.


Oregon Buttes on the horizon. Nearly
all of the land in the sunlight on the
horizon is part of a giant gold deposit
known as the Dickie Springs-Oregon
Buttes paleoplacer estimaed to
contain >28.5 million ounces of gold
according to the USGS.




Pit dug into gold-bearing
paleoplacer at Dickie Springs















The greatest gold concentrations in the greenstone belt occur in faults (shear zones) in the Lewiston district and in similar structures in the South Pass-Atlantic City district. These structures that geologists refer to as shear zones, were identified by past prospectors and miners. Even though the shear zones all have anomalous gold, only sporadic ore shoots of limited strike length contain minable quantities of gold. But these ore shoots occur primarily in fold closures (known as saddle reefs) that steeply plunge down into the earth to unknown depths (possibly a few thousand feet or more). Thus in some cases, some of these saddle reefs likely host hundreds of thousands to millions of ounces of gold. But all past exploration focused only on two dimensions at the surface (the length and width) when exploration should have emphasized the forgotten third dimension, which is potentially the greatest of the three. The third dimension is that of the plunge of the ore shoots which continues down dip into the earth to unknown depths. Past drilling at the Carissa mine suggests these may plunge to very great depths. Ore shoots at South Pass have the appearance of dipping rods that pinch and swell as they continue down into the earth.


Gold panned from Dickie Springs
(photo from J.D. Love).
The richest stream placers in the belt lie immediately downstream from these structures. The nearer the placer gravels lie to shear zones, the greater the amount of gold is found in the gravel. Immense amounts of gold were described by the US Geological Survey in giant paleoplacers near Oregon Buttes to the south and in the McGraw Flats area to the north. The amount of gold estimated for the Oregon Buttes paleoplacer by the US Geological Survey was 28.5 million ounces (Figure 5). All eroded from the South Pass greenstone belt.

Rock Creek placer with old tailings


Within the greenstone belt are many significant ore shoots. The richest discovered to date, was that of the Carissa lode near South Pass City. This mine lies a short distance southeast of State Highway 28.

Gold from tailings
in Rock Creek.
During mapping, I was impressed by the immensity of this gold-bearing structure. This structure consists of a prominent, relatively narrow, shear zone that has high-grade gold values. The structure averages 0.15 to 0.3 ounces per ton gold, which is not bad considering that the Homestake mine averaged about 0.3 opt throughout its lifetime. The principal structure at the Carissa is contained in a larger fracture envelope that is essentially untested and was missed by nearly every mining company. Composite chip samples collected within this larger structure over a width of many feet ranged from 0.02 to 0.07 ounce per ton gold, considered to be potentially economic and comparable to many operating gold mines in Nevada.




Gold-rich shear zone at the Carissa mine in the
South Pass Archean greenstone belt. Such shear
structures show distinct 'nugget effects' where
steeply plunging ore shoots are identified by
gold enrichment and/or fold closures. When found,
such ore shoots plunge steeply down into the earth
possibly for a few thousand or more feet. These
kind of ore shoots are common in greenstone belts
worldwide and are known as 'saddle reefs'.


Past gold production from the mine is poorly documented, but available statistics suggest 50,000 to more than 180,000 ounces of gold were produced prior to 1950. The Carissa shaft was sunk to a depth of 350 feet with more than 2,300 feet of drifts on four levels over a strike length of 750 feet. A winze was later sunk to a 5th level at a depth of 400 feet below the surface.


Steve Gyorvary standing in mine-out
portion of the Carissa shear zone. The
empty space is where the shear zone was
located.
The mined ore contained a trace to 2.6 ounces per ton of gold (opt Au). Some specimen-grade samples were recovered that assayed as high as 260 opt Au. An assay map of the mine compiled in 1926 indicates the mine terminated in mineralized rock in every direction. Later drilling in the 1970s and 1980s proved that the ore shoot continued below the mine workings suggesting the mine to have considerable potential.


The mine was developed in a shear zone in dark rock known as metagraywacke (a metamorphosed, micaceous sandstone) of the Miners Delight Formation and a mafic dike (metamorphosed igneous rock or gabbro). Essentially, all prospecting efforts concentrated on the primary shear, as it contained ore shoots of high-grade gold. The structure averaged about 6 feet wide, is 2 to 3 feet wide at the surface, but swelled to 50 feet at depth. More importantly, this primary shear lies within a much larger shear that isn’t quite as distinct and was essentially overlooked. This larger structure forms an envelope surrounding the primary shear that is >1,000 feet wide. The envelope is expressed by numerous parallel fractures with numerous quartz veinlets.
The results of the sampling suggest that the Carissa lode is a large-tonnage gold deposit that could have been developed by open pit and underground operations. The gold ore continues below the mine workings based on drilling by Anaconda Minerals Company in 1974. Anaconda intersected 16.1 feet of gold-bearing shear beneath the mine workings that averaged 0.13 opt Au. A small section in this zone assayed 1.6 opt Au! At 700 to 970 feet, the mineralized shear was intersected in four drill holes. These assayed 0.11 to 0.36 ounce per ton gold over widths of 2.3 to 11.9 feet.

In the 1980s, Consolidated McKinney Resources intersected an 80-foot mineralized zone beneath the mine workings that assayed 0.031 to 2.54 ounces per ton gold! In addition, one intercept contained >5 opt over several feet. All of these are verifiable and provide evidence for a significant to major gold deposit at the Carissa. Based on drilling, mining and surface sampling, the Carissa ore shoot has a minimum strike length of 950 feet that is open at either end. This shoot is more than 1000 feet wide and continues to a minimum depth of 970 feet and is open at depth. This shear structure is traced on the surface to the northeast and southwest for several thousand feet and most of it remains unsampled. Such shear zones typically continue to a few thousand feet deep in similar greenstone belts worldwide.
Right- folded parallel veins in the Carissa Shear Envelop. This rock
covers >1,000 feet of width surrounding the primary Carissa Shear 
and is also highly mineralized forming an ore zone that is economic and
could easily be mined by open pit. Channel samples collected in this zone
by the author ranged from 0.02 to 0.07 opt Au.
Beeler (1908) reported the ore in the primary shear to average 0.3 opt Au. Composite chip samples in the giant low-grade shear envelope enclosing this primary structure yielded anomalous gold over a width of 300 feet: these samples yielded 0.02 to 0.05 opt (Curran, 1926; Hausel, 1989). A 97-foot composite sample in this zone assayed 0.023 opt Au and a 30-foot composite assayed 0.07 opt Au (Hausel, 1991a): at today’s gold prices these would be considered economic. The remaining envelope (700 feet) remains unsampled, but undoubtedly contains gold based on the structure and presence of secondary quartz.

Based on sampling, the Carissa has a distinct mineralized zone that is likely a few thousand feet deep, as much as 1,000 feet wide, and 1,000 feet along strike. However, the mineralized zone is open in all three directions and could be enlarged considerably with additional drilling.

This would suggest, that at an average ore grade of 0.1 opt Au, this zone potentially hosts 3.7 million ounces of unmined gold worth $4.4 billion dollars. This does not include potential resources deeper than 1,000 feet or further along the strike length of the shear. In effect, the Wyoming State legislature and Governor removed (nationalized) a major gold deposit from the public sector that would have created numerous jobs in Fremont County and provided a significant tax base to Wyoming and Fremont County. Instead, in the wisdom we have come to love in government, Wyoming now has a mining Disneyland sitting on a major ore deposit. This Disneyland may produce a few thousand dollars in revenue for the state while at the same time it sucks out a few $hundred thousand for budget and salaries to operate the Wyoming Disneyland park.

The people who operate the South Pass City historic site are very good at what they do and should be respected for their knowledge. But the legislature and governor should have their heads examined. This Disneyland appears to be spreading in a district that could provide many future jobs. Dollars set aside for Federal abandoned mine reclamation programs were used to rebuild the Carissa surface buildings and are being used to rebuild buildings on private land at the Duncan mine, another probable ore body. When will government ever be required to pay for their actions?
_________________________________________________________________________

Table 1. Chip channel and channel sample analyses in the South Pass greenstone belt (Hausel, 1989a).
_________________________________________________________________________

SAMPLE DESCRIPTION Au
Carissa Mine (low-grade envelope) (ppm)
0 to 10 ft north of shear 0.4
10 to 20 ft north of shear 1.05
20 to 37 ft north of shear 2.5
0 to 10 ft south of shear 0.65
10 to 20 ft south of shear 0.25
20 to 30 ft south of shear 0.30
30 to 60 ft south of shear 0.35
30 ft composite north of shear 2.4
_________________________________________________________________________

The State of Wyoming purchased the Carissa mine
(which sits on a major gold deposit) and
withdrew the property from mining to reconstruct
a monument to mining where no man can mine again. This
was done by the State Legislature without considering the
geology and ore deposits. Now the old workings attract a
few hundred people a year while they sit on top of a gold
deposit estimated to contain more than a few $billion in gold
The Carissa ore is structurally controlled and is interpreted as a saddle reef deposit where high-grade gold is localized in fold closures and rehealed fractures similar to the Homestake. The geological evidence suggests the ore-body continues to great depth. Support for the presence of a major ore deposit includes drilling by Consolidated McKinney Resources who identified a highly anomalous 80-foot wide mineralized zone. Carissa Gold Inc. made the a reserve estimate years ago without knowing there was a major shear envelope and had no data on the mineralized structure beneath the mine working. Using an extraordinary high reserve cutoff grade: 208,000 tons of ore at an average grade of 0.343 opt Au; and geological reserves of 37,000 tons of ore averaging 0.85 opt Au.

Anaconda Minerals Company drilled the property prior to Consolidated McKinney Resources and all of their drill holes interested ore grade material. They intersected a high grade ore zone over widths of 2.3 to 16.1 feet that yielded 0.11 to 0.36 opt Au to depths of 700 feet.

The Wyoming legislature & governor did what the Shoshone Indians of the past could not do. The Wyoming legislature ‘nationalized’ this mine by purchasing private property and incorporating it into the South Pass City historical site without considering geological studies or scientific testimony. This was likely one of the two best gold targets in the state. The other is located within the Rattlesnake Hills where a multi-million ounce gold deposit is currently being drilled.
Part of the reconstruction of the Carissa mine
Adjacent to the mine is a dry gulch locally known as Carissa gulch. This gulch drains into Willow Creek from the western extent of the lode. The eastern extent of the lode is sampled by nearby Hermit Gulch. Both gulches should provide excellent places to hunt for nuggets with metal detectors, but again, these have been withdrawn from exploration as has been Willow Creek. Willow Creek is purported to have dangerous mercury levels based solely on here say, yet it would likely produce significant gold values.

Other properties of interest at South Pass include Miners Delight and the Wolf mine along with thousands of feet of unexplored shear zones in the South Pass-Atlantic City district, the Lewiston district, and in the Crows nest. The Miners Delight mine has a very attractive shear structure that yielded a 0.68 opt Au channel sample across about 8 feet and the Wolf mine yielded a grab sample that assayed 0.5 opt Au. This shear is poorly exposed by was trenched by one company that showed a shear that was 160 feet wide (Steve Gyorvary, personal communication, 2010).


The Duncan mine. Another gold deposit
sits under this property, but it too is
being made into a govenment monument.
It sits on
private property but this did not stopped
the state of Wyoming to invest tax-payer
funds to rebuild this as a monument
to mining where no man can mine again.
Other interesting deposits in Wyoming include the Rattlesnake Hills and Seminoe greenstone belts. The author identified a few hundred gold anomalies at South Pass, found the first several significant gold anomalies in the Rattlesnake Hills, identified a significant gold anomaly in the Seminoe Mountains and identified another gold anomaly at Copper Mountain. The Elmer’s Rock greenstone belt remains essentially unexplored for mineralization even though several indicator minerals have been found in that region that suggest the presence of several hidden diamond deposits. In addition, two world-class colored gemstone deposits were found along the flanks of the Elmer’s Rock belt that remains relatively unexplored. The author also identified excellent gold targets in the Sierra Madre, southern Laramie Range, Bearlodge Mountains and Mineral Hill (Hausel, 1987).

However, due to the lack of regard for the mining sector and prospectors, the author recommends that companies and prospectors come to Arizona, Nevada or Canada to search for gold.

Recommended Reading

Blackstone, D.L., and Hausel, W.D., 1991, Guide to the geology and mineralization of the Seminoe Mountains, Wyoming, in S. Roberts, editor, Mineral Resources of Wyoming: Wyoming Geological Association 42nd Annual Field Conference Guidebook, p. 201-210.

Graff, P.J., Sears, J.W., Holden, G.S., and Hausel, W.D., 1982, Geology of Elmer’s Rock greenstone belt, Laramie Range, Wyoming: Geological Survey of Wyoming Report of Investigations 14, 22 p.

Hausel, W.D., 1987, Structural control of Archean gold mineralization within the South Pass greenstone terrain, Wyoming (USA), in The Practical Applications of Trace Elements and Isotopes to Environmental Biogeochemistry and Mineral Resources Evaluation, Theophrastus Publications, Athens, Greece, p.199-216.

Hausel, W.D., 1989, The Geology of Wyoming's Precious Metal Lode & Placer Deposits: Geological Survey of Wyoming Bulletin 68, 248 p.

Hausel, W.D., 1991, Economic Geology of the South Pass Granite-Greenstone Belt, Wind River Mountains, Western Wyoming. Geological Survey of Wyoming Report of Investigations 44, 129 p.

Hausel, W.D., 1993, Mining History and geology of some of Wyoming’s metal and gemstone districts: in Wyoming Geological Association Jubilee Anniversary Field Conference Guidebook, p. 39-64.

Hausel, W.D., 1994, Economic Geology of the Seminoe Mountains Mining District, Carbon County, Wyoming: Wyoming State Geological Survey Report of Investigations 50, 31 p.

Hausel, W.D., 1996, Economic Geology of the Rattlesnake Hills Supracrustal Belt, Natrona County, Wyoming: Geological Survey of Wyoming Report of Investigations 52, 28 p.

Hausel, W.D., 1997, The Geology of Wyoming's Copper, Lead, Zinc, Molybdenum and Associated Metal Deposits: Geological Survey of Wyoming Bulletin 70, 224 p.

Hausel, W.D., 2009, Gems, Minerals and Rocks of Wyoming - A Guide for Rock Hounds, Prospectors & Collectors. Booksurge, 175 p.

Hausel, W.D., and Hausel, E.J., 2011, GOLD - Field Guide for Prospectors and Geologists (Wyoming Examples). CreateSpace, 366 p.

Hausel, W.D., and Love, J.D., 1991, Guide to the geology and mineralization of the South Pass area, in S. Roberts, editor, Mineral Resources of Wyoming: Wyoming Geological Association 42nd Annual Field Conference Guidebook, p. 181-200.

Snyder, G.L., Hausel, W.D., Klein, T.L., Houston, R.S., and Graff, P.J., 1989, Precambrian Rocks & Mineralization, Wyoming Province: 28th International Geological Congress guide to field trip T-332, July 19-25, 48 p.



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