Biotite /ˈbʌɪətʌɪt/ – mineral KFe2(OH,F)2(AlSi3O10) belonging to the class of iron-rich silicates used in the production of cement, paint, electrical insulators or KMg3(OH, F2)(AlSi3O12)
Ex. The geological sample revealed the presence of biotite, a mineral known for its dark color and sheet-like structure