The Ferris-Haggarty mine is located within the Grand Encampment district of the Sierra Madre Mountains. The Sierra Madre are a forest covered mountain range that rise from the valley floors of the adjacent Great Divide and Platte River Valley basins to over 10,700 feet at Bridger Peak in the heart of the range. Nearby towns include Encampment, Saratoga, Baggs, Sinclair and Rawlins. The district is known for hundreds of historic mines and prospect pits that were dug to test for copper, nickel, cobalt, platinum, palladium, zinc, lead, tantalum, rare earth metals, garnet and/or gold. The district recently was of interest for platinum-group metals and nickel following discovery of anomalous nickel, palladium, gold, copper, silver and platinum (Hausel, 1995, 1997). and typically attracts hundreds of prospectors and treasure hunters each year to search for gold and diamonds.
Ore specimen from the Ferris-Haggarty ore shoot. One of the great mysteries
about the F-H mine was the type of ore since the mine had been inaccessible
for nearly a hundred years; yet this was one of the greatest copper mines in
the world in the 19th century.
Investigations by Exxon Minerals in the 1980s
identified a sizable gold anomaly at the mine, but the deposit remained
basically unexplored along trend and depth (and still does). This specimen
suggests considerable brecciation of the ore and replacement of the matrix with
massive copper. The deposit lies in the middle of Proterozoic schists deposited
near an island arc possibly 1.6 billion years ago, and is in the middle of a
known massive sulfide district due to initial research by Conoco
Minerals in the late 1970s. Some volcanogenic massive sulfide deposits
mined in Canada and in Arizona have produced $billions in metals. It is
likely that the Ferris-Haggarty still contains sizable ore resources and the
surrounding region contains several economic massive sulfides - however,
during the 1980s, the US Forest Service piecemeal withdrew land following
every discovery of a massive sulfide deposit in the Sierra Madre Mountains
of Wyoming essentially nationalizing our natural resources.
For the people who still enjoy working, if the FS would support these kinds of
projects instead of withdrawing land, Wyomingites and Coloradoites could
have hundreds of high-paying mining jobs if any of these massive sulfides were
|Author and geologist - GemHunter Dan|
|Historical photo of the Ferris Haggarty mine with Tram|
|Underground at the Ferris-Haggarty mine.|
|Ore zone exposed in the workings of the F-H mine - in this part of the mine|
the ore give the appearance of mill rock.
It is interesting that the ore was described to occur as fault breccia in quartzite along a contact with schist (Spencer, 1904). Examination of the ore zone by the author showed that it was indeed brecciated and deformed in a shear zone, but that relatively undeformed samples of the ore showed the ore appears as mill rock - associated with a massive sulfide deposit. The matrix of this breccia consists of massive copper ore supporting angular lithic fragments. Thus the adjacent sericitic schist may represent metamorphosed felsic volcanic rock. Until geochemistry and mapping can be completed for the Ferris-Haggarty mine, it may best to refer to the host rock as felsic schist or volcaniclastic. The significance of mill rock is important as similar mill rock has been described elsewhere in the district - such as at the Itmay mine, where mill rock was first described in the district by Conoco Minerals in the early 1980s (Hausel, 1997).
|You can find more information about this|
copper and gold deposit in our Gold book
Millrock was initially coined by a geologist in Canada when it was recognized many volcaniclastic breccias and their associated ore deposits were found near or adjacent to an operating mill in districts like the Flin Flon massive sulfide district in Canada. The concept was that where you found mill rock with its massive sulfides, you had potentially had a commercial ore deposit. At the time of deposition of the Ferris-Haggarty deposit, about 2 billion years ago, the earth’s atmosphere was starting to accumulate oxygen from stromatolites and their associated reefs.
|Ore zone in the Ferris-Haggarty mine (mill rock)|
|Uncommon sulfide ore from Ferris-Haggarty ore zone showing|
chalcopyrite, bornite and malachite.
|One of many Precambrian quartz pebble conglomerates found in the|
Medicine Bow and Sierra Madre Mountains of Wyoming.