Pegmatite
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A pegmatite is an igneous rock showing a very coarse texture, with large interlocking crystals usually greater in size than 1 cm and sometimes greater than 1 meter. Most pegmatites are composed of qua
Pegmatite with blue corundum crystals
Pegmatite containing lepidolite, tourmaline, and quartz from the White Elephant Mine in the Black Hills, South Dakota
Proterozoic pegmatite swarm in the headwall of the cirque of a small mountain glacier, northeastern Baffin Island, Nunavut
Rose muscovite from the Harding Pegmatite Mine
Mica
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Micas are a group of silicate minerals whose outstanding physical characteristic is that individual mica crystals can easily be split into fragile elastic plates. This characteristic is described as p
Pegmatite
…crystals usually greater in size than 1 cm (0.4 in) and sometimes greater than 1 meter (3 ft). Most pegmatites are composed of quartz, feldspar, and mica, having a similar silicic composition to granite. However, rarer intermediate composition and mafic pegmatites are known. Many of the world's largest…
Mica
Sheets of mica
Photomicrographs of a thin section containing phlogopite. In cross-polarized light on the left, plane-polarized light on the right.
Dark mica from eastern Ontario