Geology and Ore Deposits of the Breckenridge Mining District, Colorado |
Common terms and phrases
ankerite belt Benton shale black shale Boreas Pass Breckenridge district Bullhide fault carbonate cerusite chalcopyrite Colorado containing Cretaceous crude ore shipped Dakota quartzite dips Dunkin east enrichment Eocene epidote Fault vein feet thick fissures fold fractures French Gulch Front Range galena geology Gibson Hill gold Golddust gouge gray quartzite gray shale grit high-grade Illinois Gulch intrusive limestone limonite limy shale Little Mountain Main vein Maroon formation masses Massive miles minerals mines Morrison formation Nigger Hill Niobrara formation northeast Northern fault Northern vein occurs Oro shaft orthoclase ounces oxidized phenocrysts Pierre shale plate pre-Cambrian pre-Cambrian rocks premineral probably Puzzle vein pyrite quartz monzonite porphyry Ransome region relation Rocky Point sandstone seam sediments sericite shaly shoot short tons shown sill silver sixth level solutions southeast special area sphalerite stope sulphate sulphide surface Thin-bedded thrust fault U.S. Geol upper Wellington wet assay Willard tunnel writer zinc