Phosphophyllite

Phosphophyllite is a rare mineral composed of hydrated zinc phosphate. Its name derives from its chemical composition (phosphate) and the Greek word for "leaf", phyllon, a reference to its cleavage.[2] It is highly prized by collectors for its rarity and for its delicate bluish green colour. Phosphophyllite is rarely cut because it is fragile and brittle, and large crystals are too valuable to be broken up.[3]

Phosphophyllite
General
CategoryPhosphate minerals
Formula
(repeating unit)		hydrated zinc phosphate Zn2Fe(PO4)2•4H2O
Strunz classification8.CA.40
Crystal systemMonoclinic
Crystal classPrismatic (2/m)
(same H-M symbol)
Space groupP21/c
Identification
Formula mass448.40 g/mol
ColorBlue-green to colourless
Crystal habitPrismatic
TwinningCommon
Cleavage[100] Perfect, [010] Distinct, [102] Distinct
FractureConchoidal
Mohs scale hardness3.5
LusterVitreous
StreakWhite
DiaphaneityTransparent
Specific gravity3.1
Refractive index1.59-1.62
Birefringence0.021
Common impuritiesManganese
References[1]

The finest phosphophyllite crystals come from Potosí, Bolivia, but it is no longer mined there. Other sources include New Hampshire, United States and Hagendorf, Bavaria, Germany. It is often found in association with the minerals chalcopyrite and triphylite.[4]

Twinned Phosphophyllite, Unificada Mine, Cerro de Potosí, Potosí Department, Bolivia. 2.1 x 1.4 x 1 cm.

References
  1. Mineralienatlas
  2. "Phosphophyllite". Retrieved 2006-12-16.
  3. Hall, Cally (1994). Gemstones. Great Britain: Dorling Kindersley. p. 127. ISBN 0-7513-1026-3.
  4. "The mineral phosphophyllite". Amethyst Galleries, Inc. Archived from the original on 2006-10-17. Retrieved 2006-12-16.
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