Limestone

Limestone is a sedimentary rock consisting mainly of the mineral calcite (calcium carbonate) with or without dolomite (magnesium carbonate). The color of limestone is altered by the presence of impurities, which broaden the color spectrum of limestone to include white, brown, gray, buff, yellow, red, block, or mixtures of these colors.

Limestone, being of sedimentary origin, is usually quite anisotropic, or "directionally specific" in its behavior. This accounts for a pronounced "rift", or plane of easiest splitting, within most limestone types.