— biotitic /buy'euh tit"ik/ , adj.
/buy"euh tuyt'/ , n.
a very common mineral of the mica group, occurring in black, dark-brown, or dark-green sheets and flakes: an important constituent of igneous and metamorphic rocks.
[ 1860-65; named after J. B. Biot (1774-1862), French mineralogist and mathematician; see -ITE 1 ]