Faustite

The IMA approved mineral faustite,[1] named after the American mineralogist and petrologist with the U.S. Geological Survey (USGS) Dr. George Tobias Faust,[2] is a member of the triclinic turquoise group of hydrous phosphates with the following chemical composition:

ZnAl6(PO4)4(OH)8·4H2O

Some divalent copper generally replaces the zinc position. Faustite is the zinc rich analogue of turquoise having almost four times as much zinc than copper in its crystal structure.[3] Trivalent (ferric) iron may replace some of the aluminum. Minor amounts of calcium may also be present. It has a hardness of 4.5 - 5.5 on the Mohs scale of mineral hardness and aside from having a slightly lower hardness, it may be difficult to distinguish it from turquoise in hand specimens.

Faustite has a blue-green to apple green color in polished cabochons, and may be presented as a turquoise imitation, and it may also be treated with stabilizers for jewelry making.

References

  1. ↑ "Faustite" (PDF). RRUFF Project. Mineral Data Publishing. Retrieved 8 April 2014.
  2. ↑ "Faustite: Faustite mineral information and data". Mindat.org. Retrieved 2014-04-08.
  3. ↑ "Faustite Mineral Data". Webmineral.com. Retrieved 2014-04-08.
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