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.
更多biotite例句
Hornblende and biotite are the ferromagnesian constituents and vary much in relative importance.
Biotite, if present, is brown; epidote is yellow or colourless; rutile, apatite and quartz all occur with some frequency.
Minettes contain biotite and orthoclase; kersantites, biotite and plagioclase.
Both in the hand specimens and in microscopic slides of lamprophyric rocks biotite and hornblende are usually conspicuous.
A special group of monchiquites rich in deep brown biotite has been called fourchites (after the Fourche Mountains, Arkansas).