Sericite

 ( Phyllosilicates ) 

Sericite is the name given to very fine, ragged grains and aggregates of white (colourless) micas, typically made of muscovite, illite, or paragonite.

Sericite is produced by the alteration of orthoclase or plagioclase in areas that have been subjected to hydrothermal alteration (also see Sericitic alteration) typically associated with copper, tin, or other hydrothermal ore deposits. Sericite also occurs as the fine mica that gives the sheen to phyllite and metamorphic rocks.

The name comes from Latin sericus, meaning "silken" in reference to the location from which silk was first utilized, which in turn refers to the silky sheen of rocks with abundant sericite.

birefringence flakes covering other larger minerals)"> File:Granite pmg ss 2006.jpg|Granite in thin section under cross-polarized light in which feldspar crystals exhibit sericite alteration File:Staurolite garnet schist 3mm xp 2007.jpg|Staurolite-garnet schist in thin section under cross-polarized light with sericite

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External links

• Mindat
• Microscopic image

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