Saussurite n. : A tough, compact mineral, of a white, greenish, or grayish color. It is near zoisite in composition, and in part, at least, has been produced by the alteration of feldspar.

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Taxonomy
Saussurite, free encyclopedia, simulant, zoisite, jade, true mineral, minerals, search, aggregate, alteration product, grayish-green color, substitute, mixture, sodium, the Swiss, plagioclase feldspar, slopes, silicate mineral.

Defination from the web:
Saussurite is a mineral aggregate which is formed as a hydrothermal alteration product of plagioclase feldspar. ... The use of microscopic refractive index data and X-ray diffraction patterns are needed to distinguish some saussurite simulants from true jade. ...