Purpurite - Collected from Southwest Africa by Robert Herod. Mineral collection of Brigham Young University Department of Geology, Provo, Utah - BYU index 9-3106, (Mn 3+ ,Fe 3+ )PO 4 — Photo: Andrew Silver · Public domain
Purpurite
A manganese phosphate ranging from violet to dark red — the oxidized product of lithiophilite in pegmatites.
Intro adapted from Wikipedia (CC BY-SA).
Purpurite is an IMA-recognized mineral species in the phosphate class, with the chemical formula Mn³⁺(PO₄).
It crystallizes in the orthorhombic crystal system (space group Pbnm). It is a member of the Olivine structural group.
Key properties: Mohs hardness 4–4.5; specific gravity 3.2–3.4; Pale purple to pale red streak; Satiny on fresh fractures luster; refractive index 1.939; optically biaxial.
IMA symbol Pur, grandfathered status — known before the IMA’s founding, named in 1905.
Derived from oxidation and leaching of primary Mn–Fe phosphates, particularly lithiophilite, in complex granite pegmatites; rarely, formed by reaction between bat guano and Fe–Mn deposits resulting from seawater ingress.
It is found associated with Lithiophilite, sicklerite, many secondary Fe–Mn phosphates.
The name comes from the Latin for purple, in allusion to its typical color.