Lepidolite is a lilac-gray or rose-colored member of the mica group of minerals with chemical formula K(Li,Al)3(Al,Si,Rb)4O10(F,OH)2. It is the most abundant lithium-bearing mineral and is a secondary source of this metal. It is the major source of the alkali metal rubidium.
Lepidolite
Yellow lepidolite from Itinga, Minas Gerais, Brazil. Size: 6.1 x 4.9 x 3.1 cm
Lavender lepidolite "books" from Himalaya Mine, Mesa Grande District, San Diego County, California, US. Size: 4.8 x 3.9 x 3.5 cm
Lepidolite, Virgem da Lapa, Minas Gerais, Brazil (size 2.4 x 2.1 x 0.7 cm)
Micas are a group of silicate minerals whose outstanding physical characteristic is that individual mica crystals can easily be split into extremely thin elastic plates. This characteristic is described as perfect basal cleavage. Mica is common in igneous and metamorphic rock and is occasionally found as small flakes in sedimentary rock. It is particularly prominent in many granites, pegmatites, and schists, and "books" of mica several feet across have been found in some pegmatites.
Mica
Sheets of mica
Photomicrographs of a thin section containing phlogopite. In cross-polarized light on left, plane-polarized light on right.
Dark mica from eastern Ontario