Phosphophyllite
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| Phosphophyllite | |
|---|---|
 | |
| General | |
| Category | Phosphate minerals |
| Formula | Zn2Fe(PO4)2·4H2O |
| IMA symbol | Pp[1] |
| Strunz classification | 8.CA.40 |
| Crystal system | Monoclinic |
| Crystal class | Prismatic (2/m) (same H-M symbol) |
| Space group | P21/c |
| Identification | |
| Formula mass | 448.40 g/mol |
| Color | Blue-green to colourless |
| Crystal habit | Prismatic |
| Twinning | Common |
| Cleavage | [100] Perfect, [010] Distinct, [102] Distinct |
| Fracture | Conchoidal |
| Mohs scale hardness | 3.5 |
| Luster | Vitreous |
| Streak | White |
| Diaphaneity | Transparent |
| Specific gravity | 3.1 |
| Optical properties | Biaxial (−) |
| Refractive index | nα = 1.595–1.599, nβ = 1.614–1.617, nγ = 1.616–1.620 |
| Birefringence | 0.021 |
| 2V angle | Measured 44°, Calculated 34° |
| Common impurities | Manganese |
| References | [2] |
Phosphophyllite is a rare phosphate mineral with the chemical formula Zn2Fe(PO4)2·4H2O. It is prized among mineral collectors for its delicate bluish green colour, but rarely cut due to its difficult properties.
Phosphophyllite was first described in 1920 by Heinrich Laubmann and Hermann Steinmetz.[3] The name derives from Ancient Greek phyllon 'leaf', and phosphate.[4]
Chemically, phosphophyllite is related to zinc phosphate with some zinc substituted by iron. Phosphophyllite has been synthesized by the addition of diammonium phosphate to a solution of zinc and iron sulfate.[5]
Occurrence
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.[6]
Uses
Phosphophyllite is highly prized by collectors for its rarity and for its delicate bluish green colour but brittleness and fragility as well as the intrinsic value of large crystals make it unsuitable for jewelry.[7]
