muscovite mica from a pegmatite near Coronel Murta, Minas Gerais, Brazil - display specimen roughly half/half

roughly half/half

were mobilized either by magmatic or metamorphic processes in the underlying crystalline rocks or by the compaction of Triassic platform carbonates

The Allison Member of the Upper Cretaceous Menefee Formation is a cliff-forming yellow brown sandstone

Select a set: You can select a set by telling us what is in the photo with it

which means you can't scratch it with a fingernail

muscovite mica from a pegmatite near Coronel Murta, Minas Gerais, Brazil - display specimen roughly half/halfmuscovite mica KAL3Si3O10(OH)2 Coronel Murta, Minas Gerais, Brazil Muscovite is a common rock forming mineral. In pegmatites, which are essentially giant crystal granitic rocks, muscovite forms large books and can be cleaved into large sheets. It is mined commercially for use as an insulator in transformers and electrical equipment. Scrap muscovite, small flakes, is used as a filler or extender in paints. Transparent in thin sheets, muscovite is