The Gladiator Mine, Lake City, Colorado; the mineralogy and paragenesis of an epithermal base- and precious-metal vein system

Abstract

A fissure-filling epithermal vein, which is exposed in the Gladiator mine, Lake City, Colorado, is similar in size and mineralogy to many other veins in the area. The vein mineralogy of this nonproducing mine is dominated by common epithermal base-metal and gangue minerals. Silver, which is the most abundant precious metal in the vein, occurring in concentrations up to 500 ppm in selected samples, is present in tetrahedrite and rare acanthite. Although gold was detectable in trace amounts (1-10 ppm) by analytical techniques, no Au or Au-bearing minerals were observed in hand specimen or petrographically. Three principal stages of mineralization were differentiated in the vein exposed in the Gladiator mine. From oldest to youngest these include: I quartz-sericite-pyrite; Ila sphalerite-galena, lib Cu-sulfide; Ilia quartz-barite-rhodochrosite, and Illb late barite-quartz. In general, each of these assemblages is paragenetically distinct; however, some overlapping of individual minerals within assemblages is common. Six primary fluid inclusions from stage I quartz were measured by R.F. Sanford (unpublished data). Homogenization temperatures ranged from 189.6-224.5 C and averaged 208 C. These temperatures are at the low end of the range for fluid inclusions from the Lake City area.