Economic Geology and the Bulletin of the Society of Economic Geologists, Volume 21

abundant amount anticlines bakelite balsam banding Bighorn Basin bornite Boydell brecciated calcite carbon carborundum cassiterite cement cent chalcocite chalcopyrite Clinton sand Cloth coal containing copper crystals deposits depth dikes ECONOMIC GEOLOGY electrum evidence feet fissures folds formed fractures fragments galena gangue gas fields gas pools geologist Golden Eagle Golden Eagle field grains granite greenstone grinding hematite hypogene Illus intrusion iron formation lateral migration limestone magma magnetite material Meeteetse Mesaverde formation metasomatism microscope miles minerals Mining occur oil and gas origin oxide Petrographic Petroleum plate polishing polybasite pore spaces porous porphyry present pressure production pyrargyrite pyrite pyrrhotite quantities quartz region replacement reservoir beds sandstone schist sericite shale shows siderite silica silver solutions source beds specimen sphalerite strata structure sulphides supergene surface temperature tennantite Tertiary tetrahedrite thickness tion trough U. S. Geol U. S. Geological Survey upper veinlets veins writer zone