Bulletin, Issues 943-944

abundant Alaska altered amounts aplite appears arsenopyrite basalt base-metal batholith beds Belshazzar biotite bismuth minerals bodies Boise Basin Boise Ridge BULLETIN 944 PLATE chalcopyrite coarse commonly contains country rock crosscut crystals deposits depth dikes diorite distribution drifts drusy early Tertiary east exposed fault feet long feet wide fissure zone footwall Fork fracture zones galena Geology Gold Hill gouge grains granitic rock gray Grimes Creek Grimes Pass groundmass Gulch hanging wall Idaho batholith Idaho City intrusion lamprophyric lenses limestone Lindgren locally Mayflower metals miles mill mining Miocene Norquist northeast occurs orthoclase ounces outcrop Payette River percent phenocrysts phosphate rock places plagioclase porphyry porphyry belt production pyrite quartz monzonite quartz monzonite porphyry quartz seams Quartzburg rhyolite seams and stringers sericitized shaft shale shearing shoots siderite silver slope sphalerite stoped strike structural sulfides surface tetrahedrite thrust trend tunnel U. S. Geol valley Whitedelf younger