Purpurite

Purpurite
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General
Category	Phosphate minerals
Formula (repeating unit)	Mn3+PO4
Strunz classification	08.AB.10
Identification
Formula mass	149.91
Color	Brownish black, violet, dark pink, dark red, reddish purple
Crystal habit	Massive to granular
Crystal system	Orthorhombic (2/m 2/m 2/m) Space Group: P nmb
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, basically manganese phosphate, MnPO₄ although with varying amounts of iron depending upon the source of the mineral. It is a striking pink purple color as might be expected of a manganese-containing mineral.

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