Purpurite

Purpurite
Purpurite from Namibia
General
CategoryPhosphate minerals
Formula
(repeating unit)
Mn3+PO4
IMA symbolPur[1]
Strunz classification8.AB.10
Crystal systemOrthorhombic
Crystal classDipyramidal (mmm)
H-M symbol: (2/m 2/m 2/m)
Space groupPnmb
Identification
Formula mass149.91 g/mol
ColorBrownish black, violet, dark pink, dark red, reddish purple
Crystal habitMassive to granular
Cleavage[100] [001] perfect
FractureUneven
TenacityBrittle
Mohs scale hardness4–5
LusterEarthy
Streakred
Specific gravity3.2 – 3.4
Optical propertiesBiaxial (+)
Refractive indexnα = 1.850(2) nβ = 1.860(2) nγ = 1.920(2)
Birefringenceδ = 0.070
2V angle38°
References[2][3][4]

Purpurite is a manganese phosphate mineral with the formula MnPO4, with varying amounts of iron depending upon its source. It occurs in color ranges from brownish black via purple and violet to dark red.[3]

Purpurite forms a series with the iron-bearing endmember heterosite, FePO4.[4]

  1. ^ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.
  2. ^ Mineralienatlas
  3. ^ a b "Purpurite". Webminerals. Retrieved 2009-06-06.
  4. ^ a b Mindat