Biotite mica is a black, platy mineral which forms in sheets, it belongs to the mica group of minerals which also includes muscovite, phlogopite and lepidolite micas. Being a common phyllosilicate mineral, it is also found in many rocks, particularly of igneous and metamorphic origin, such as mica schist, gneisses and granites. The crystal system of mica in general is monoclinic and like other mica minerals, biotite has a perfect basal cleavage and consists of flexible sheets or lamellae, which easily flake off, with tabular to prismatic crystals. When Biotite is found in large masses it's referred to as "books" as it resembles their many pages. These mineral specimens of biotite mica comes from Arendal in Norway and was collected by our own staff, the specimens are supplied in labelled card trays and are available in optional sizes to choose from.