Sericite

Sericite is a common alteration mineral of orthoclase or plagioclase feldspars in areas that have been subjected to hydrothermal 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 schistose metamorphic rocks. Named in 1852 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.

Bibliography

• Cox et al. (1979): The Interpretation of Igneous Rocks, George Allen and Unwin, London.
• Howie, R. A., Zussman, J., & Deer, W. (1992). An introduction to the rock-forming minerals (p. 696). Longman.
• Le Maitre, R. W., Streckeisen, A., Zanettin, B., Le Bas, M. J., Bonin, B., Bateman, P., & Lameyre, J. (2002). Igneous rocks. A classification and glossary of terms, 2. Cambridge University Press.
• Middlemost, E. A. (1986). Magmas and magmatic rocks: an introduction to igneous petrology.
• Shelley, D. (1993). Igneous and metamorphic rocks under the microscope: classification, textures, microstructures and mineral preferred-orientations.
• Vernon, R. H. & Clarke, G. L. (2008): Principles of Metamorphic Petrology. Cambridge University Press.

Photo
Plagioclase altered by sericite. PPL image, 10x (Field of view = 2mm)	Plagioclase altered by sericite. XPL image, 10x (Field of view = 2mm)/td>	Plagioclase altered by sericite. XPL image, 10x (Field of view = 2mm)/td>
Plagioclase altered by sericite. XPL image, 10x (Field of view = 2mm)	Plagioclase altered by sericite. XPL image, 10x (Field of view = 2mm)	Plagioclase altered by sericite. XPL image, 10x (Field of view = 2mm)
Orthoclase altered by sericite. PPL image, 2x (Field of view = 7mm)	Plagioclase crystals altered by sericite in a granite. XPL image, 2x (Field of view = 7mm)	Plagioclase crystal altered by sericite in a granite. XPL image, 10x (Field of view = 2mm)
Plagioclase crystal altered by sericite in a granite. XPL image, 10x (Field of view = 2mm)	Plagioclase crystal altered by sericite in a granite. XPL image, 10x (Field of view = 2mm)	Plagioclase crystal altered by sericite (the brown material) in a Granite. Gipfel des Brocken im Harz (Germany). PPL image, 10x (Field of view = 2mm)
Plagioclase crystal altered by sericite (the brown material) in a Granite. Gipfel des Brocken im Harz (Germany). PPL image, 10x (Field of view = 2mm)	Plagioclase crystal altered by sericite (the brown material) in a Granite. Gipfel des Brocken im Harz (Germany). PPL image, 10x (Field of view = 2mm)	Plagioclase crystal altered by sericite (the brown material) in a Granite. Gipfel des Brocken im Harz (Germany). PPL image, 10x (Field of view = 2mm)
Plagioclase crystals altered by sericite (the brown material) in a Granite. PPL image, 2x (Field of view = 7mm)	Plagioclase crystals altered by sericite (the brown material) in a Granite. PPL image, 2x (Field of view = 7mm)	Plagioclase crystals altered by sericite in a granite. XPL image, 2x (Field of view = 7mm)
Plagioclase crystals altered by sericite (the brown material) in a Granite. PPL image, 2x (Field of view = 7mm)	Plagioclase crystals altered by sericite (the brown material) in a Granite. PPL image, 2x (Field of view = 7mm)	Plagioclase crystals altered by sericite in a granite. XPL image, 2x (Field of view = 7mm)
Plagioclase crystals altered by sericite (the gray material). Note the difference with the colorless-not altered quartz. PPL image, 10x (Field of view = 2mm)	Plagioclase crystals altered by sericite (the gray material). Note the difference with the colorless-not altered quartz. PPL image, 10x (Field of view = 2mm)	Plagioclase crystals altered by sericite. XPL image, 10x (Field of view = 2mm)
Plagioclase crystals altered by sericite (the gray material). Note the difference with the colorless-not altered quartz. PPL image, 10x (Field of view = 2mm)	Plagioclase crystals altered by sericite. XPL image, 10x (Field of view = 2mm)	Plagioclase crystals altered by sericite (the gray material). Note the difference with the colorless-not altered quartz. PPL image, 10x (Field of view = 2mm)
Plagioclase crystal altered by sericite. PPL image, 20x (Field of view = 1mm)	Plagioclase crystal altered by sericite. PPL image, 20x (Field of view = 1mm)