PHOSPHOPHYLLITE: Potosi, Bolivia (8.1)
Phosphophyllite possesses a color almost unique in gems, a lovely blue-green shade enhanced by cutting. This is a very rare mineral. Stones are seldom available because of lack of incentive to cut up good crystals. Few large stones exist; the material is quite brittle and fragile and very difficult to cut, with an easily developed cleavage. This is one of the more desirable of the collector gems as well as one of the more expensive ones. Analysis has shown the Bolivian material to be almost Mn-free, unlike the German material that contains Mn.
Phosphophyllite Value
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Phosphophyllite Information
| Data | Value |
| Name | Phosphophyllite |
| Crystallography | Monoclinic. Crystals prismatic to tabular, well developed. |
| Colors | Colorless to blue-green. |
| Luster | Vitreous. |
| Hardness | 3-3.5. |
| Density | 108-3. 13. |
| Birefringence | 0.021—0.033. |
| Cleavage | Perfect 1 direction. Fracture uneven. Brittle. |
| Stone Sizes | Only Bolivian material has been cut, but some crystals have been found that could yield stones of about 75 carats or more. These are superb and very rare crystal specimens and will undoubtedly never be cut. Most stones are in the 1-10 carat range, cut from crystal fragments and broken crystals. Smithsonian Institution (Washington, D.C): 26.9 (Bolivia). Private Collection: 74, flawless (Bolivia). Devonian Group (Calgary, Alberta, Canada): 5.25 (Bolivia). |
| Luminescence | Fluoresces violet in SW. |
| Spectral | Not diagnostic. |
| Formula | Zn2(Fe,Mn)(PO4)2 · 4H2O. |
| Pleochroism | None. |
Optics: a=1.595-1.599; β= 1.614-1.616; γ=1.616-1.621.
Biaxial (-). 2V: 45°.
Occurrence: in massive sulfide deposits (Bolivia) and in granite pegmatites (Germany)
Potosi, Bolivia: magnificent single crystals up to about 3×2 inches; refractive indices of this material 1.597—1 .621, density 3.08, fine blue-green color, transparent.
Hagendarf, Germany: small crystals associated with secondary phosphate minerals.
Comments: Phosphophyllite possesses a color almost unique in gems, a lovely blue-green shade enhanced by cutting. This is a very rare mineral. Stones are seldom available because of lack of incentive to cut up good crystals. Few large stones exist; the material is quite brittle and fragile and very difficult to cut, with an easily developed cleavage. This is one of the more desirable of the collector gems as well as one of the more expensive ones. Analysis has shown the Bolivian material to be almost Mn-free, unlike the German material that contains Mn.
Name: After Greek words for phosphorus-bearing and cleavable.
