Economic Geology, Volume 56

alteration amounts analyses aquifer associated beds bornite breccia Bull calcite carbonate chalcocite chalcopyrite chemical chert Chibougamau Chinle chlorite cobalt composition concentration contain copper deposits crystals diatremes dikes district dolomite EcoN ECONOMIC GEOLOGY elements faults feet feldspar fluids fluorite formation formed fractures galena Geological Survey geologists grains granite ground-water hematite hydrothermal igneous Illus inclusions indicate intrusive iron iron-formation isotopic Lake layers lead lignite limestone lower magma magnetite manganese marcasite metals metamorphic miles minerals mining Neyveli nickel occur orebodies origin oxide pebble percent phyllite Precambrian present pressure pyrite Pyrite Body pyrrhotite quartz quartzite radioactive range reaction replacement samples sandstone schist sedimentary sediments siderite silicate soluble solutions specimens sphalerite stratigraphic structure Sudbury sulfate sulfides sulfur surface Table tbls Temiscamie temperature tephroite Tertiary tetrahedrite texture thick thorite tion U. S. Geol uraninite uranium vapor veinlets veins volcanic zone