Perthite is used to describe an intergrowth of two feldspars: a host grain of potassium-rich alkali feldspar (near K-feldspar, KAlSi3O8, in composition) includes exsolved lamellae or irregular intergrowths of sodic alkali feldspar (near albite, NaAlSi3O8, in composition). Typically the host grain is orthoclase or microcline, and the lamellae are a...
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http://en.wikipedia.org/wiki/Perthite
• (n.) A kind of feldspar consisting of a laminated intertexture of albite and orthoclase, usually of different colors.
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http://thinkexist.com/dictionary/meaning/perthite/
any member of a class of alkali feldspars in which tiny crystals of sodium-rich feldspar (albite; NaAlSi3O8) are intimately intergrown with, but ... [1 related articles]
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http://www.britannica.com/eb/a-z/p/48
Perth'ite noun [ So called from
Perth , in canada.]
(Min.) A kind of feldspar consisting of a laminated intertexture of albite and orthoclase, usually of different colors. --
Per*thit'ic adjective Found on
http://www.encyclo.co.uk/webster/P/63
Perthite is a variety of orthoclase feldspar or microcline in which small veinlets of plagioclase feldspar (albite) are present. It is a common mineral in rocks such as granite and syenite.
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http://www.probertencyclopaedia.com/browse/HP.HTM
an intimate mixture of either microcline or orthoclase and a sodium-rich plagioclase (commonly albite).
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https://www.encyclo.co.uk/local/20132
Describes the intergrowth of two feldspars; potassium-rich alkali feldspar, and lamellae intergrowths of sodic alkali feldspar.
Found on
https://www.encyclo.co.uk/local/22070
No exact match found.
