Triphylite from Minas Gerais, Brazil, exhibition at the Sorbonne University mineral collection (20 January 2026–2 January 2027). — Photo: Marie-Lan Taÿ Pamart · CC BY 4.0
Triphylite
Lithium iron phosphate — the LiFePO₄ mineral, now famous as a battery cathode material.
Intro adapted from Wikipedia (CC BY-SA).
Triphylite is an IMA-recognized mineral species in the phosphate class, with the chemical formula LiFe²⁺(PO₄).
It crystallizes in the orthorhombic crystal system (space group Pbnm). It is a member of the Olivine structural group.
Key properties: Mohs hardness 4–5; specific gravity 3.5–3.58; typically green or gray or brown; White to grayish white streak; Vitreous to subresinous luster; refractive index 1.689; optically biaxial.
IMA symbol Trp, grandfathered status — known before the IMA’s founding, named in 1834.
The most abundant primary phosphate in complex zoned granite pegmatites.
It is found associated with Ferrisicklerite, heterosite, alluaudite, many other Fe–Mn phosphates and oxides.
Its name comes from the Greek for threefold and family, as it contains three cations.
Collections: Collector Favorites.