Meaning of BIOTITE in English

or black mica

mica group.

It is abundant in metamorphic rocks, in pegmatites, and in granites and other igneous rocks. Biotite is a layer silicate structure in which aluminum and silicon occur in infinitely extending Si-Al-O sheets that alternate with potassium-rich and magnesium-(and iron-) containing sheets.

Britannica English dictionary.      Английский словарь Британика.