Another member, which is found in granite pegmatites was used by Bunsen and Kirchoff to discover Rubidium.
One ultramafic variety of this mineral class, phlogopite, is known for coming in very large plates also known as "books." Along with Zinnwaldite, it forms a series within this class based on iron content that ends with this class's most notable member. This class of minerals which shows bird's eye extinction patterns is used in Geiger counters. Another member, which is found in granite pegmatites was used by Bunsen and Kirchoff to discover Rubidium. In addition to the Lithium containing Lepidolite, this class of minerals most notable members are the aluminium rich Muscovite and the iron rich biotite. For 10 points, name this phyllosilicate mineral class which is notable for having perfect basal cleavage.
One ultramafic variety of this mineral class, phlogopite, is known for coming in very large plates also known as "books.
mica