August 17, 2023 by Mcnair, B. Basalt is a hard, fine-grained, dark-colored volcanic or extrusive rock. It has primarily calcium-rich plagioclase and augite. Also, it may have minor amounts of other minerals like quartz, olivine, foids, alkali feldspar, biotite, and amphibole. This rock is undoubtedly popular, only rivaled by granite.