It was July. The cool mountain air blended with the harsh Wyoming sun making the day pleasant. Winter had finally receded, but an occasional snow drift provided reminders that Mr. Gore and Global Warming were a figment of someone's imagination. I drove into the heart of the Medicine Bow Mountains with a group of prospecting students. The course curriculum called for a gold panning session with discussions of gold and diamonds in fluvial systems. Our caravan entered into the Bobbie Thompson Campground on Douglas Creek just south of the Keystone village.
We climbed out of the vehicles, I asked the students to think about the specific gravity of gold (15 to 19.3 times heavier than water) and where we might expect to find it in the this drainage. The group focused on many large boulders in the creek, suggesting the stones acted as obstacles to stream velocity providing natural traps for gold. Other class members suggested much of the gold would be located on bedrock at depth (~10 feet down at this particular location). I pointed out that gold is often concentrated by flash flooding events, and it is up to the prospector and geologist to find evidence for these events. But without a backhoe, mining permit, a major bond, 5 to 10 years of time to waste on obtaining permits, we were restricted to discussing theoretical possibilities.
If we could dig to bed rock, it would be prudent to sample the entire vertical stratigraphic section in the drainage to search for lenses with concentrations of black sand, pebbles and cobbles, as these should provide evidence of flash flooding events and lead to paystreaks. Some of these horizons might even be more productive than bedrock.
I pointed out that the Douglas Creek stratigraphy extended beyond the stream. Where we were standing, 15 feet from, and 2 or 3 feet higher than the water level of the creek, we were on gravel deposited by Douglas Creek in the past. No one else had recognized this - they were too focused on the active stream.
To prove my point, I asked the class to get their gold pans, screens (grizzlies) and shovels, and sample the dry gravel next to the campground. As the did, they then transported the gravel-filled pans to water in Douglas Creek, and the excitement was contagious as one by one, tiny pinpoints of native gold were found in the gold pans.
I told the class to also keep an eye out for diamonds and kimberlitic indicator minerals (pyrope garnet, chromium diopside, picroilmenite) as the Medicine Bow National Forest was located within a geological terrain considered to have high potential for the discovery of diamonds. Not far from here, two excellent octahedral diamonds were found on Cortez Creek. These minerals have specific gravities ranging from 3.2 to 3.8 and will be found with the black sand concentrates.
The Boden diamonds - found on Cortez Creek by a gold prospector in 1977. These are excellent, gem-quality stones (millimeter scale).
The class on that particular day convened 3 miles downstream from the original gold strike in 1868 by Ira Moore. The area of the strike, named in honor of the discoverer, has ever since been known as Moore’s Gulch. A historical gold camp established nearby was called Last Chance, possibly an indication of the frustrations often associated with prospecting.
Moore’s Gulch is a tributary of Douglas Creek. The headwaters of Douglas Creek originate a few miles to the north of Moore’s Gulch, and from the headwaters, Douglas Creek runs in a southerly direction for several miles until it makes a sharp bend to the west before joining the North Platte River 12 to 14 miles from Moore’s Gulch. The union of these waterways lies along the western flank of the Medicine Bow Mountains.
The district is generally considered to encompass all placers along Douglas Creek and its tributaries. Another district was later established within the confluence of Douglas Creek, known as the Keystone district. This district includes some lodes along the banks of Douglas creek south of Ira Moore’s initial discovery.
Another district overlaps a portion of the Douglas Creek district to the northwest of Keystone, which is known as the New Rambler district. This district focused on the New Rambler mine – one of the few historic palladium and platinum mines in North America. From 1900 to 1918, the New Rambler produced copper, gold, silver, palladium and platinum (Hausel, 2000a). More recently several palladium, platinum and nickel anomalies have been detected in the nearby Lake Owen, Mullen Creek, and Puzzler Hill areas (Hausel, 2000b).
The Medicine Bow Mountains, which includes these districts, is highly fractured and interpreted to have high potential for the discovery of diamonds. Diamonds were found on Cortez Creek to the northwest of Douglas Creek by Paul Boden in 1977, and kimberlitic indicator mineral anomalies (notably pyrope garnet) have been found at several locations in the forest since the first diamonds were found. It is also notable that the two largest kimberlite districts in the United States lie within 20 miles of the Medicine Bow National Forest. One has been the source of more than 130,000 gem and industrial quality diamonds. To a geologist, the Medicine Bow Mountains lie along the edge of a craton (ancient continental core) that is considered favorable terrain to hunt diamonds as well as gold, platinum-group metals, nickel, chromium, titanium, vanadium, tantalum, copper, and several other precious, strategic and base metals.
Currently, Douglas Creek is a popular place where prospectors experience the cold waters of the creek while they dredge for gold.
The historical information and gold production data for the Douglas Creek are sketchy. However, history indicates Ira Moore discovered gold in 1868, and the district (also referred to as the Foley district) was organized. In the following year, about 400 ounces of placer gold were recovered.
According to Henry Beeler, a territorial geologist, gravel in the district typically contained gold values that ranged from 0.017 to 0.085 oz/yd3, and the precious metal was in the form of flour to coarse nuggets. As much as 25% of the gold was coarse and jagged with nuggets weighing 5 to 20 pennyweights (1 ounce = 20 pennyweights). The largest nugget found during the early activity weighed 3.4 ounces, and the purity of the gold ranged from 0.890 to 0.960 fine (1.000 fine = pure gold). Impurities included as much as 10% silver and traces of platinum.
Gravel along Douglas Creek was 3 to 20 feet thick and averaged 5 feet thick. Estimated resources for some placers were reported by Beeler (1906) as:
Douglas Ck 3,020,160 yd3 0.024 oz/yd3 72,485 ounces
Daves Creek 70,000 yd3 - -
Moores Gulch 60,000 yd3 >0.048 oz/yd3 >2880 ounces
Elk & Bear Cks 250,000 yd3 - -
During the early activities on Douglas Creek, the mining operations were separated into three properties: Albany, Home, and Douglas Creek Consolidated placers.
Albany Placers. The Albany placers were located near the headwaters, and included about 5 miles of Douglas Creek and all or portions of Moores Gulch, Elk Creek, Bear Creek, and Daves Creek. The Rob Roy reservoir, later constructed on Douglas Creek, flooded large portions of these placers.
Gold from these placers was coarse and jagged with considerable flour with traces of platinum and palladium. In one early test, 25 yards of gravel between Daves and Douglas Creek was mined and yielded 1.5 ounces of gold with some platinum and palladium. Another 2,200 yards of gravel were mined that averaged 0.077 oz/yd3 and yielded 170 ounces of gold.
Moores Gulch placers yielded 500 ounces of gold and were reportedly exhausted by 1870 (Knight, 1893). However, Beeler (1906) reported that another 60,000 yds3 of gold-bearing gravel remained unmined.
Home Placers. The largest nugget found on Douglas Creek prior to 1906 was recovered from the Home placers. These continue south of the Albany Placers and north of the Douglas Creek Consolidated Placers. This operation covered 4 to 5 miles of Douglas Creek beginning just south of Moores Gulch, and also included Little Beaver Creek to the east. Much of Little Beaver Creek was not favorable for mining due the large size and abundance of boulders in the drainage.
Some testing on the Home placers included a 150-foot traverse along Douglas Creek north of Keystone. This pan tested at 0.045 oz/yd3. About 900 feet north of this traverse, a crosscut traverse was dug and pan tested at 0.05 oz/yd3.
Below the mouth of Little Beaver Creek the gravel was not as coarse and the drainage open up into Willow Flat, an 800 x 2000-foot area with 3 to 8 feet of gravel. The gravel mined at Willow Flat, yielded values ranging from 0.008 to 0.012 oz/yd3.
In 1935, the Medicine Bow Mining Company operated a dragline and constructed a floating washing plant south of the village of Keystone. The company processed 48,176 cubic yards of gravel and recovered 287 ounces of gold and 34 ounces of silver (Hausel, 1989). Later, in 1958, the Moe Brothers Company used a similar dragline to mine gravel 1.5 miles north of the Keystone village near Gold Run. The amount of gold recovered from this operation is unknown.
Douglas Creek Consolidated Placers. The Douglas Creek Consolidated Placers continue south of the Home placers for about 8 miles along Douglas Creek and included 5 miles of Muddy Creek. In one test on Muddy Creek in 1896, prospectors dug a 15x48 x7-foot test pit and recovered 9.75 ounces of gold. The gold included two nuggets weighing 0.2 and 0.4 ounces. Other pan tests yielded 0.019 to 0.029 oz/yd3. Muddy Creek was reported to average 4 feet to bedrock. Average tests on Douglas Creek within the placer gave 0.04 oz/yd3 (Beeler, 1906). Pan tests within a 160-foot traverse a few miles to the south near Pelton Creek tested 0.034 to 0.085 oz/yd3.
Some other placers lie near Douglas Creek. These include the Lincoln Gulch, Small, Spring Creek, and Fox Creek.
Gold (and pyrope garnet (small red crystal) recovered from Douglas Creek by Paul Allred.
Lincoln Gulch Placers. A 3-mile placer on Lincoln Gulch to the east of Douglas Creek was reported to yield 20 to 80 ounces of gold annually prior to 1906. In places, the gravel was reported to be 20 feet thick.
Small Placer. Located above the mouth of Muddy Creek east of Keystone. The gravel was reported to be rich and to average 0.1 oz/yd3.
Spring Creek Placers. The need for running water in Spring Creek, a tributary of Muddy Creek, led a group of prospectors to dig 1000 feet of bedrock flume, 4,500 feet of ditch with 600 feet of fluming for hydraulic mining. A partial cleanup of the flume concentrates from 1200 yds3 yielded 50 ounces of gold (Hausel, 1993a, b). Much of the gold from Spring Creek was coarse with nuggets weighing 0.05 to 1 ounce. Many of the nuggets still had quartz attached to the gold, indicating a proximal source. Recently a 2.5-ounce nugget was found on Spring Creek (Robert E. Jones, pers. comm. 1988).
Fox Creek Placer. Located east of Douglas Creek and south of Lincoln Gulch. Some gravel mined from this placer yielded 0.012 oz/yd3 in gold.
Bear Creek. This placer, located south of Fox Park and south of Douglas Creek, yielded some 0.5 to 1-inch nuggets (Robert E. Jones, personal communication, 1988).
Keystone-Florence Shear zone. South of the Mullen Creek-Nash Fork shear zone within the Proterozoic age rocks are several significant precious and base metal deposits that include quartz veins, massive sulfides, porphyry copper-gold mineralization, and layered mafic intrusions with palladium, platinum, gold, copper, vanadium and chromium. In the Keystone district of the Medicine Bow Mountains, N60°W-trending shears provide loci for narrow veins. These are gold- and copper-bearing, pyritic, quartz-carbonate veins in tensional faults subsidiary to the Mullen Creek-Nash Fork shear zone (Curry, 1965). Mineralization was accompanied by silicification in the form of small, irregular, quartz veinlets. The wallrock is enriched in epidote.
At the Keystone mine, gold was found in quartz along with pyrite and pyrrhotite masses in mylonite selvages adjacent to the vein. The vein lies in sheared diabase that intrudes quartz-biotite gneiss country rock (Curry, 1965). The shear is 2 to 6 feet wide, locally splays to 300 feet, and continues 4,500 feet to the southeast to the Florence mine. Available information indicates that the Keystone ore averaged 1.3 opt Au. When the mine ceased operations in 1893, 100,000 tons of ore were reported in site of the mine workings. Eight selected samples collected from the mine dump by Loucks (1976) yielded 0.19 to 8.75 opt Au and averaged 3.41 opt Au, verifying the presence of high-grade gold in this deposit.
At the southeastern end of the Keystone trend, the Florence mine was developed in quartz diorite. The ore occurred as 'kidneys' of auriferous pyrite that assayed from 7.5 to 48 opt Au (Curry, 1965). Samples collected from the mine dump by Loucks (1976) yielded 0.06 to 23.3 opt Au. Samples with visible gold were found in limonite boxworks after pyrite.
The extent and gold values from the Keystone-Florence shear trend suggest this deposit could be a significant gold deposit, nearly all of it hidden under soil and regolith between the two mines. The extent of the shear structures beyond the mines is unknown, but this provides another example of a potentially major gold deposit overlooked by past and present miners. The deposit needs to be mapped in detail by the WGS with associated resistivity geophysical surveys to attract an exploration company to the area.
Total gold production from Douglas Creek is unknown, but exceeded 4,000 ounces. Unfortunately, Douglas Creek is limited in size, but the creek itself, and some of its tributaries, have not been thoroughly prospected. Modern day prospectors working in the district often find coarse gold, some amalgamated gold, platinum and palladium. And there is a very good possibility of finding diamonds in Douglas Creek. For example, myself and Wayne Sutherland identified several cryptovolcanic structures near Douglas Creek that are probably kimberlite pipes.
The source of the gold from Douglas Creek is thought to be derived from a parallel group of northwest-trending shear zones that are cut by the creek and some of its tributaries. Mapping by Currey (1964) shows a few northwest-trending mineralized shears along Douglas Creek. One of these is cut by Moores Gulch and is probably the source of gold in that placer as well as the Albany Placers along Douglas Creek.
Two parallel gold-bearing shear zones further to the south may be the source of much of the gold in the Home and Douglas Creek Consolidated placers. Most notable is the Keystone-Florence shear zone that is intersected by Douglas Creek and probably continues further east into Spring Creek. Historical reports indicate that both the Keystone and Florence mines intersected some rich ore shoots near the surface. In fact, I found some excellent samples of quartz with considerable visible gold on the Florence mine dump. Thus this shear may be the source of the coarse gold found on Spring Creek, and it may suggest that a one-mile extension of this shear zone has gone undetected.
Beeler, H.C., 1906, Mineral and allied resources of Albany County, Wyoming: Office of the State Geologist, miscellaneous printed report, Cheyenne Wyoming, 79 p.
Currey, D.R., 1965, The Keystone gold-copper prospect area, Albany County, Wyoming: Geological Survey of Wyoming Preliminary Report 3, 12 p.
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., 1993a, Mining history and geology of some of Wyoming's metal and gemstone districts and deposits: Wyoming Geological Association Jubilee Field Conference Guidebook, p. 39-63.
Hausel, W.D., 1993b, Guide to the geology, mining districts, and ghost towns of the Medicine Bow Mountains and Snowy Range scenic byway: Geological Survey of Wyoming Public Information Circular 32, 53 p.
Hausel, W.D., 2000a, The Centennial lode and the Centennial Ridge district, Wyoming: International California Mining Journal, v. 70, no. 2, p. 14-22.
Hausel, W.D., 2000b, The Wyoming platinum-palladium-nickel province: geology and mineralization: Wyoming Geological Association Field Conference Guidebook, p. 15-27.
Knight, W.C., 1893, Notes on the mineral resources of the State: University of Wyoming Experiment Station Bulletin 14, p. 103-212.