muscovite mica from a pegmatite near Coronel Murta, Minas Gerais, Brazil - hand/display specimen but you can scratch it

but you can scratch it with a penny to confirm the identification

was published by Kernen in 1924

Contributions to Mineralogy and Petrology 164 (3): 477 - 492 [2012]

as revealed by recent infrared fluorescence spectroscopy and is not graphite-rich dolomitic limestone as formerly thought

This peat is silty

muscovite mica from a pegmatite near Coronel Murta, Minas Gerais, Brazil - hand/display specimen but you can scratch itmuscovite 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