Rocks Classified and Described: A Treatise on Lithology

accessory according acid aggregates amygdaloidal appear argillaceous augite basalt become beds belong brown called carbonate causes cavities character chemical chiefly clay clay-slate Cleavage coal colour combined compact composition compound consists contains Crown 8vo crystalline schists crystals deposits diorite distinct distinguished dolomite earthy Edition especially essential felspar formation Fracture frequently geol geological Germ given gives gneiss grains granite granular green grey History hornblende igneous rocks imbedded ingredients instance iron Jahrb kinds labradorite latter less lime limestone Lustre magnetic iron-ore mass matrix mica mica-schist mineral nature occurs oligoclase origin orthoclase period phonolite plutonic porphyritic present principal probably pyrites quantity quartz rarely recent References result sandstone sedimentary separate serpentine shale silica similar sometimes stone strata structure substance surface syenite term texture tion titanite trachyte transition transmutation usually varieties various veins vesicular vitreous volcanic