black granite
Rock species known to petrologists as diabase, diorite, gabbro and other varieties quarried as dimension stone. As dimension blocks or slabs, they are valued specifically for their dark grey to black color when polished. Scientifically, they are far removed in composition from true granites though they may be satisfactorily used for some of the purposes to which commercial granites are adapted. They possess an interlocking crystalline texture, but unlike granites, they contain little or no quartz or alkalic feldspar, and are characterized by an abundance of one or more of the common black rock-forming minerals (chiefly pyroxenes, hornblende, and biotite). (Marble Institute, 2011)