Triphylite is a lithium iron(II) phosphate mineral with the chemical formula LiFePO<sub>4</sub>. It is a member of the triphylite group and forms a complete solid solution series with the lithium manganese(II) phosphate, lithiophilite. Triphylite crystallizes in the orthorhombic crystal system. It rarely forms prismatic crystals and is more frequently found in hypidiomorphic rock. It is bluish- to greenish-gray in color, but upon alteration becomes brown to black.
Etymology and history
The mineral was first discovered and examined in 1834 by German mineralogist Johann Nepomuk von Fuchs at Hennenkobel Mine in the Bavarian Forest. The name derives from the Greek words tri ("three") and phulon ("family"), referring to the three cations found in natural samples of triphylite (Li<sup>+</sup>, Fe<sup>2+</sup>, Mn<sup>2+</sup>).
Properties
Triphylite is soluble in hydrochloric and sulfuric acid. Under a blowpipe, it melts to form a dark gray, magnetic ball.