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Turquoise after Fluorapatite


Turquoise is a hydrous copper aluminum phosphate. Known since ancient times, turquoise derives its name from the French adjective for Turkish, since the original material from Persia came to Europe via Turkey (Pogue, 1915). Turquoise usually forms seams and nuggets admixed with clay. The typical admixture with clay, combined with minute grain size, led to much early confusion about turquoise chemistry (Pogue, 1915). The discovery of free-standing turquoise microcrystals in Virginia allowed resolution of its formula (Schaller, 1912). The first crystal structure determination of turquoise used Schaller's material (Cid-Dresdner, 1965). Modern definitions of turquoise and related species are given in Foord & Taggart (1988).

In the American Southwest and northern Mexico, turquoise forms in the alteration "sericitized" zones of copper porphyry deposits. This particular turquoise likely derived its phosphate content from a fluorapatite crystal, which it replaced while preserving the fluorapatite crystal form. This pseudomorph dates to find circa 2009-2010. Quite sharp for one of these!

Price: $75

Item code: MS1397

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