Economic Geology

acid Amer amounts analyses anhydrite associated barite basin beds bituminous bodies Bull calcite Calif California Cambrian Canada carbonate Carboniferous cement cent chalcocite chalcopyrite chiefly clay coal color contain copper County Creek Cretaceous crystalline deposits depth dikes district dolomite Econ fault feet feldspar fissures formation galena gangue garnet geologic gneiss gold granite graphite gypsum hematite Ibid igneous rocks important Inst intrusive iron Jour known Lake lime limestone limonite Lindgren lodes magmatic magnetite manganese masses metallic metamorphic mica miles minerals Mines occur Ontario origin oxide pegmatite phosphate placers porphyry pre-Cambrian production pyrite pyrrhotite quarried quartz quartzite region replacement Rept residual rhyolite salt sand sandstone schists sedimentary sediments serpentine shales short tons showing silicates silver slate solutions sphalerite stone sulphate sulphides sulphur surface Surv Tertiary thickness Trans U. S. Bur U. S. Geol United Utah veins Virginia volcanic wall rock zinc zone