|Volcaniclastic in the Douglas Creek gold district. Such breccias are often|
mineralized with gold or base metals and are worthy of a close look.
If we were able to dig down 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 flood events and lead to paystreaks. Some of these horizons might even be more productive than bedrock.
I pointed out to the group that the Douglas Creek drainage extended beyond the active stream. We were standing 20 feet from the creek and 2 or 3 feet higher than the water level, but this was gravel deposited by Douglas Creek in the relatively recent past – so it should also contain gold.
|Map of mineralized terrains and districts of Wyoming |
showing location of
Douglas Creek in red (compiled by W. Dan Hausel).
To prove my point, I asked the group to get their gold pans, screens, grizzlies and shovels and sample the dry gravel next to the campground. They started to dig with excitement each dreaming about the gold nugget they were about to find. The digging was difficult because of all of the boulders, but they were all able to find some dirt. They worked this material through their grizzly pans that had quarter inch holes drilled in the pans. These were designed to remove the coarse gravel. No nuggets were seen in the grizzlies so one by one the students discarded the waste rock. Next they worked the material through the screens we had purchased at the local hardware store: just fly screen used in screen doors and windows with 4 mm2 openings. The screen is used to speed up the panning process. The material that worked through the screen was panned first – you could hear the excitement as class members started to recognize black sands. The excitement was contagious tiny pinpoints of gold were found in the pans.
I told them to think back to the lecture on alumina-rich gemstones – remember what sapphire and ruby looked like? I asked them to watch for these as Wyoming has many corundum deposits.
LOCATION & SETTING
|Keystone gneiss, Douglas Creek|
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.
Much of the gold-bearing gravel in Douglas Creek is 8,500 to 9,000 feet above sea level. 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 northwest of Keystone, which is known as the New Rambler district. This latter district was build around the New Rambler mine – one of the few historic palladium and platinum mines in North America. From 1900 to 1918, the New Rambler mine produced copper, gold, silver, palladium and platinum. Palladium and platinum were also detected in nearby mines, and other platinum anomalies were detected several years later in the Centennial Ridge district 6 to 8 miles to the northeast (Hausel, 2000a). More recently palladium, platinum chromium and titanium anomalies were identified in the nearby Lake Owen and Mullen Creek areas. A few companies exploring Lake Owen and Mullen Creek identified some thick, mineralized cumulates in the layered complexes that yielded very interesting palladium anomalies. In 1997, I discovered a very interesting anomaly at Puzzler Hill, a complex everyone else missed, but had highly anomalous palladium, nickel and minor copper, gold, silver and platinum (Hausel, 2000b). At the nearby Charter Oak mine, I recovered some very nice specularite specimens which were cut and polished into some very attractive cabochons.
The Boden diamonds found on Cortez Creek north of Douglas Creek in 1977.
Geologically, the Medicine Bow Mountains, which includes all of these mining districts (with the exception of Puzzler Hill), is highly fractured and interpreted to have high potential for 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) were found at several locations in the forest since the first diamonds were found in the forest. 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 of these has been the source of more than 130,000 gem and industrial quality diamonds that included microdiamonds to macrodiamonds weighing more than 28 carats. To a geologist, the Medicine Bow Mountains lie along the edge of a craton (ancient continental core) that is considered favorable terrain to hunt for diamonds, as well as gold, platinum-group metals, nickel, chromium, titanium, vanadium, tantalum, copper, several other precious, strategic and base metals, including ruby and sapphire.
Gold dredged from Douglas Creek by Paul Allred near the Bobbie Thompson Campground. Note the tiny red garnet sitting on a flake near the large nugget – this turned out to be a pyrope garnet (diamond indicator mineral).
Currently, Douglas Creek is a popular place where prospectors experience the cold waters of the creek while they dredge and pan for gold. The nearest towns are Saratoga and Encampment, about 20 miles as the crow flies to the west. Centennial is located 10 miles as the crow flies to the northeast. Laramie lies 30 miles east of Centennial.
DOUGLAS CREEK DISTRICT
The historical information and gold production data for the Douglas Creek district are sketchy. However, history indicates that Ira Moore discovered gold in 1868, and the Douglas Creek district (originally referred to as the Foley district) was organized. In the following year, about 400 ounces of placer gold were recovered.
The author stands on makeshift dragline left by early gold miners near Moore’s Gulch.
According to Henry Beeler, a territorial geologist in the late 1800s, gravel in the district typically contained gold values ranging 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 fact that there is this much jagged gold suggests that it originated in the immediate area. Jagged gold is mostly found adjacent to a lode deposit because gold is so malleable that it is rapidly smoothed into rounded and flattened grains in active streams. There are some lodes in this area, but probably not enough to account for all of the jagged placer gold in the district. This suggests a good possibility for hidden lodes.
The largest reported nugget found during the early gold mining activity weighed 3.4 ounces. Larger nuggets may have been found and not reported. The purity of the gold was 0.890 to 0.960 fine (1.000 fine = pure gold). Impurities in natural gold usually include as much as 10% silver and traces of platinum and palladium. The gravel along Douglas Creek is 3 to 20 feet thick and averages 5 feet thick. Estimated resources for some placers were reported by Beeler (1906) as:
PLACER NAME GRAVEL VOLUME GRADE CONTAINED GOLD
Douglas Creek 3,020,160 yd3 0.024 oz/yd3 72,485 ounces
Dave’s Creek 70,000 yd3 unknown unknown
Moore’s Gulch 60,000 yd3 >0.048 oz/yd3 >2880 ounces
Elk & Bear Creeks 250,000 yd3 unknown unknown
During the early activities on Douglas Creek, the mining operations were separated into three properties: Albany, Home, and Douglas Creek Consolidated placers.
Gold panned from Douglas Creek.
Albany Placers. The Albany placers were located in the north near the headwaters, and included about 5 miles of Douglas Creek and all or portions of Moore’s Gulch, Elk Creek, Bear Creek, and Dave’s 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 Dave’s 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 produced 170 ounces of gold. Moore’s Gulch placers yielded 500 ounces of gold and were reportedly exhausted by 1870 (Knight, 1893). However, Beeler (1906) reported another 60,000 yds3 of gold-bearing gravel remained unmined in contradiction to the earlier report.
Home Placers. The largest nugget found on Douglas Creek prior to 1906 was recovered from the Home placers. The Home Placers continued 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 Moore’s 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.
|Typical black sand concentrates from Douglas Creek, Wyoming|
Below the mouth of Little Beaver Creek the gravel was not as coarse and the drainage opened up into Willow Flat, a 800 by 2000-foot area that had 3 to 8 feet thick gravels. 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 yds3 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 mine 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 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 averaged 0.034 to 0.085 oz/yd3. Some other placers lie near Douglas Creek including Lincoln Gulch, Small, Spring Creek, and Fox Creek.
|Amphibolite gneiss located near Douglas Creek|
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 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 so they could hydraulically mine the drainage. 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. A 2.5-ounce nugget was found on Spring Creek in the 1980s (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).
Total gold production from Douglas Creek is unknown, but exceeded 4000 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 Douglas Creek district often find coarse gold, some amalgamated gold (gold amalgamated with mercury), platinum and palladium. And there is a good possibility of finding diamonds and other gemstones in Douglas Creek.
The source of the gold from Douglas Creek is thought to be from a parallel group of northwest-trending shear zones that are cut by the creek and some of its tributaries. Mapping by Curry (1964) showed a few northwest-trending mineralized shears along Douglas Creek. One of these is cut by Moore’s Gulch and is probably the source of gold in that placer as well as the Albany Placers along Douglas Creek.
One of several cryptovolcanic structures found in the Medicine Bow Mountains. This one is located adjacent to Douglas Creek. The circular depression in Precambrian basement appears to be structurally controlled. The origin of the depression remains unknown.
Two parallel gold-bearing shear zones further to the south may be the source of some 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 one excellent sample of quartz with considerable visible gold on the Florence mine dump a few years ago. Thus this shear may be the source of some coarse gold found on Spring Creek, and it may suggest that a one-mile extension of this shear zone has gone undetected.
Historical photo (1905) of the Keystone mine along Douglas Creek. About 5,000 to 10,000 ounces of gold were recovered from this mine between 1876 and 1893. The shaft was sunk 365 feet and included 5,000 feet of drifts (photo from the S.H. Knight Collection, University of Wyoming American Heritage Center).
Beeler, H.C., 1906, Mineral and allied resources of Albany County, Wyoming: Office of the State Geologist, miscellaneous printed report, Cheyenne Wyoming, 79 p.
Curry, 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.
|Dang! Now where was that breccia?|