VULCAN MINE GOLD ORE
Here's a rare, vintage sample of gold ore from
Gunnison County, Colorado's Vulcan Mine (next to the Mammoth Chimney
Mine & Good Hope Mine). The mining area is at the “town” of Vulcan,
north of the Iron Hill Carbonatite Complex and south of the eastern end of the
Blue Mesa Reservoir (= dammed Gunnison River).
Little geologic literature appears to be available on
the geology of the Vulcan Mine. The specimen shown below was the subject
of a short article published in 1898. The grayish & purplish-gray
banded portions of the rock were identified by Lakes (1898) as opalite (opal
rock, composed of hydrous silica - SiO2·nH2O).
Another source of information suggests that the banded areas are
cryptocrystalline quartz (SiO2) - chert. Peripheral to
the banded rock is breccia. Finely-disseminated native gold (and/or gold
telluride?) occurs throughout the rock.
Locality:
Vulcan Mine, southern Gunnison County, southwestern Colorado, USA (~38º 20'
37" North, ~107º 00' 26" West).
Vulcan Mine gold ore (Colorado School of Mines Geology Museum, Golden,
Colorado, USA).
Vulcan Mine gold ore (Colorado School of Mines Geology Museum public
display, Golden, Colorado, USA).
Vulcan Mine gold ore - line drawing of slice from same block of rock shown
above (from Lakes, 1898).
Reference cited:
Lakes, A. 1898. Ores of the Vulcan
Mine. Mines and Minerals 18: 562-563.