Fosforipinnoite

Fosforipinnoite is a phosphate mineral in the apatite group. Its ideal formula is Ca5(PO4)3X, where X stands for fluorine, hydroxide, or chlorine. The mineral crystallizes in the hexagonal system and often forms prismatic to tabular crystals. In pure form it is colorless; impurities and solid solution with halogens or carbonate components can produce pale greens, yellows, browns, or pinkish hues. It has a vitreous to resinous luster and a white streak. The Mohs hardness is about 5 and the density around 3.1–3.2.

Fosforipinnoite occurs in igneous and metamorphic rocks, especially in late-stage crystallization environments such as pegmatites and carbonatites, and in hydrothermal veins. It is commonly associated with calcite, fluorite, quartz, and other phosphate minerals.

Economically, fosforipinnoite is of interest as a potential phosphorus source for fertilizer production, requiring processing to extract phosphate for phosphoric acid manufacture. The mineral is also valued by collectors for its associations with other phosphate-bearing phases and its occurrence in diverse rock types.

Etymology: The name reflects the phosphate-rich composition and follows conventional mineral-naming practices that reference its chemical characteristics.