Purpurite

Purpurite is a manganese-iron phosphate mineral ((Mn³⁺,Fe³⁺)PO₄), distinguished by its deep violet-purple color. Purpurite forms through the oxidation and weathering of lithiophilite, a lithium-manganese-iron phosphate found in granitic pegmatites. When lithiophilite is exposed to weathering, lithium is leached out and the remaining manganese oxidizes from Mn²⁺ to Mn³⁺, creating the deep purple color.

The transformation can be written as a chemical weathering sequence: lithiophilite (gray-brown) weathers to purpurite (purple) as lithium departs and manganese oxidizes. If the original mineral was triphylite (the iron-dominant end member), the weathering product is heterosite (dark purple to black).

Purpurite's rich violet-purple color is among the most saturated natural purples in the mineral kingdom. The manganese(III) chromophore produces a deep, warm purple distinct from the cooler violet of amethyst or the blue-purple of charoite.

Purpurite is identified by its deep violet-purple color, purple streak (unusual among minerals), matte to satiny luster, and association with weathered pegmatite phosphates. Hardness around 4.5 and the distinctive purple streak are diagnostic.

Distinguish from sugilite (harder, different association), charoite (harder, swirling patterns), and dyed howlite or magnesite (check hardness and streak). Purpurite's purple streak on unglazed porcelain is its most reliable identifier.