Triphylite: Gemstones Information
Triphylite is Li(Fe2,Mn2)PO4 and forms transparent to translucent bluish grey to greenish grey to brown or black compact masses of the orthorhombic system with a perfect cleavage in one direction, hardness 4–5, SG 3.50–3.58. The RI for the alpha, beta and gamma rays is 1.675–1.694, 1.684–1.695 and 1.685–1.700, biaxial positive with birefringence 0.006–0.008. Triphylite occurs in complex-zoned granite pegmatites in which it is the most abundant primary phosphate. Large crystals are found at the G.E. Smith quarry, Newport, Sullivan County and the Palermo mine, North Groton, New Hampshire, USA.