Muscovite

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Muscovite

KAl₂[(OH)₂|AlSi₃O₁₀] Monoclinic



Thin sheets of muscovite (showing it's property of flexibility) are commonly available, but good examples of crystals are not particularly common. Almost all of the specimens are from pegmatites, with Brazil being the most prolific. Also sometimes sheets of muscovite with various inclusions are sold.

The earliest use of muscovite was for jewelry. The first major use of muscovite was as a window pane for wood and coal burning stoves. Currently sheet mica is used as an electrical insulator and in electronic capacitors. It is also used as a "glitter" component in cosmetics.

Muscovite is found in all types of rocks. It occurs as a detrital component in sandstones and arkoses, is a major component in metamorphic rocks (mica schists), as an accessory mineral in granites and pegmatites and the variety sericite is common in many hydrothermal deposits. Most commercial production is from large books in pegmatites.


The most common forms are hexagonal crystals, but you can also get star twins, and aggregates forming balls. The largest known crystal of muscovite came from the Purdy mica mine in Ontario Canada. It measured at least 2.4m long and 1.5m in diameter.


Argentina
Catamarca, Papachacra




Australia
Victoria, Lake Boga granite quarry



Austria
Salzburg, Krautgarten Mt.




Brazil
Espírito Santo, Mimoso do Sul Mine



Brazil
Minas Gerais

5 cm	© Safaa Yu

8 cm	© Rob Lavinsky

Fuchsite 6 cm	© JSS

Brazil
Minas Gerais, Divino das Laranjeiras



Brazil
Minas Gerais, Cigana claim



Brazil
Minas Gerais, Zé Pinto prospect



Brazil
Minas Gerais, Virgem da Lapa




Canada
Ontario, Nipissing District



Germany
Rhineland-Palatinate, Wannenköpfe

3 mm	© Fred Kruijen

Germany
Saxony, Neumark, Diabase quarries



Italy
Aosta Valley, Prabornaz Mine




Madagascar
Fianarantsoa Province,Malakialina pegmatites



Pakistan
Baltistan, Shengus



Portugal
Viseu District, Real quarry




USA
California, Pack Rat Mine



USA
Maine, Mt. Apatite, Maine Feldspar Quarry



USA
Maine, Lord Hill Quarry



USA
New Hampshire, Palermo No. 1 Mine



USA
New Mexico, Harding Mine

9 cm	© Rob Lavinsky

USA
North Carolina, Rist Mine



USA
North Carolina, Lincoln Co.



USA
South Dakota, Diamond Mica Mine





Pseudomorphs of Muscovite

Bolivia
Potosí Department, Llallagua



Japan
Kyoto Prefecture, Kameoka City


Variety sakura-ishi "cherry blossom stone" pseudomorphs after cordierite crystals.


USA
Arizona, Willow Spring Ranch



USA
Maine, Noyes Mountain Quarry (Harvard Quarry)



USA
New Hampshire, Atwood Mine




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Edited 8 time(s). Last edit at 03/26/2012 10:46AM by Rock Currier.