ˈbīəˌtīt noun
( -s )
Etymology: German biotit, from Jean B. Biot died 1862 French mathematician + German -it -ite
: a generally black or dark green form of mica K 2 (Mg,Fe,Al) 6 (Si,Al) 8 O 20 (OH) 4 forming a constituent of crystalline rocks and being a silicate of iron, magnesium, potassium, and aluminum (hardness 2.5-3)
• bi·o·tit·ic |bīə|tid.ik adjective