This is a rock called Biotite granite. It is a medium-grained, all crystalline rock with pink feldspar, gray quartz, and specks of black biotite - a type of mica found in igneous and metamorphic rocks.
Biotite mica is a composition of annite, phlogopite, siderophyllite, fluorophlogopite, fluorannite, eastonite, and many others.
Biotite is a rock-forming mineral found in a wide range of crystalline igneous rocks such as granite, diorite, gabbro, peridotite, and pegmatite.
Biotite has limited commercial use but may be as a filler in paints and drilling mud or as a non-stick coating on shingles.
