GEOLOGY & PLANETARY SCIENCE A  B  C  D  E  F  G  H  I  J  K  L  M  N  O  P  Q  R  S  T  U  V  W  X  Y  Z                    HOME ABOUT CATEGORIES SITE MAP COPYRIGHT ADVERTISE CONTACT entire Web this site biotite Specimen of biotite from the Adirondack Mountains, New York. Source: Wikipedia / Dave Dyet A range of iron-rich varieties of mica, grading into phlogopite. Biotite is an important rock-forming silicate mineral and a constituent of most igneous and many metamorphic rocks. It has, in common with other micas, a flaky, sheetlike structure. In color, it usually black, dark brown, or green, and has the approximate chemical formula K(Mg,Fe)3AlSi3O10(F,OH)2. Related category    • GEOLOGY AND PLANETARY SCIENCE Also on this site: Encyclopedia of Alternative Energy & Sustainable Living Encyclopedia of History Transport Concepts & Designs (partner site) BACK TO TOP