noun🔗ShareBiotitaA dark brown mica; it is a mixed aluminosilicate and fluoride of potassium, magnesium and iron."The shiny black flecks in the granite countertop are likely grains of biotite, a type of mica. "Las motas negras brillantes en la encimera de granito son probablemente granos de biotita, un tipo de mica.geologymineralsubstancematerialchemistryChat with AIVocabulary GamePractice Reading
