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Purpurite

Purpurite
Purpurite 3341.jpg
General
Category Phosphate minerals
Formula
(repeating unit)
Mn3+PO4
Strunz classification 8.AB.10
Crystal system Orthorhombic
Crystal class Dipyramidal (mmm)
H-M symbol: (2/m 2/m 2/m)
Space group Pnmb
Identification
Formula mass 149.91 g/mol
Color Brownish black, violet, dark pink, dark red, reddish purple
Crystal habit Massive to granular
Cleavage [100] [001] perfect
Fracture Brittle - uneven
Mohs scale hardness 4-5
Luster Earthy
Streak red
Specific gravity 3.2 - 3.4
Optical properties Biaxial (+) 2V 38°
Refractive index nα = 1.850(2) nβ = 1.860(2) nγ = 1.920(2)
Birefringence δ = 0.070
Other characteristics non-radioactive, non-magnetic, non-fluorescent.
References

Purpurite is a mineral, manganese phosphate, MnPO4 with varying amounts of iron depending upon its source. Like many manganese-containing minerals, it is a striking pink purple color.

Purpurite forms a series with the iron-bearing endmember heterosite, FePO4.




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