Epidote
A green, pleochroic sorosilicate mineral of metamorphic and hydrothermal origin.
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Epidote is a rock-forming mineral of secondary origin, crystallizing in the monoclinic system with a prismatic habit.[1][2] Its color is usually a characteristic yellowish-green or pistachio-green, and it displays strong pleochroism in green, yellow, and brown.[2]
Key facts and history
Epidote has the chemical formula Ca₂Al₂(Fe³⁺;Al)(SiO₄)(Si₂O₇)O(OH).[1] Many of its characters, including color, optical constants, and specific gravity, vary with the amount of iron present.[2] Well-developed crystals are found at many localities, including Knappenwand in Salzburg, the Ala valley in Piedmont, and Arendal in Norway.[2] Epidosite is the name given to a rock consisting of quartz and epidote.[2]
Gemstones have occasionally been cut from transparent, dark green epidote crystals sourced from the Knappenwand locality and from Brazil.[2] Thomas Allan first described allanite in 1808, based on material found in granite from east Greenland.[2]
References
- Wikipedia, "Epidote" (CC BY-SA 4.0), which cites: "About Epidote" (original not read by us) en.wikipedia.org
- Wikipedia, "Epidote" (CC BY-SA 4.0) en.wikipedia.org
Each numbered sentence above was checked against the source it cites before publication. Sentences citing Wikipedia adapt text from the English Wikipedia article Epidote (contributors), used under CC BY-SA 4.0; this entry is available under the same licence. Other sources were used for facts only; no text or images are copied from them.
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Sources
Compiled from Wikipedia and the sources listed below. Text from Wikipedia is available under CC BY-SA 4.0; this entry is adapted from it.
- Wikipedia: Epidote (CC BY-SA 4.0).
- Word definitions: the , each quoted from its Wikipedia article.
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