Arkose—a sand or sandstone formed of disaggregated granite or similar rock in which a notable part of the grains are feldspar or other silicate; sand when undefined, is understood to be quartzose.
Augitite—a rock mainly made up of augite.
Basalt—a dark, compact basic igneous rock consisting of a mass of minute crystals sometimes with more or less glassy base, often containing also visible crystals; composed of plagioclase and pyroxene, with olivine, magnetite, or titaniferous iron as common accessories; a basic lava in which the crystallization has taken place rapidly; usually rich in crystallites or microlites; graduates into dolerite and basic andesite.
Bituminous coal—common soft coal, intermediate between lignite and anthracite; contains much bituminous matter, i.e., hydrocarbons.
Bowlders—rounded masses of rock, particularly those that have been shaped by glaciers.
Breccia—a rock composed of angular fragments, contrasted with pudding-stone or conglomerate, in which the fragments are rounded.
Buhrstone—a compact, flint-like silicious rock full of small cavities, so named from use as millstones.
Calc-sinter (calcareous tufa)—a loose cellular deposit of calcium carbonate made by springs; travertine is the better term, as tufa should be left for volcanic elastics.
Cannel coal—a very fine-grained homogeneous bituminous coal, giving off much gas and burning with a candle-like flame.
Chalk—a fine-grained soft rock composed essentially of calcium carbonate derived from minute marine organisms.