Triphylite

Triphylite crystal in matrix, collected from Smith Quarry (Chandler Mills Quarry), Newport, New Hampshire 43°21′28″N 72°15′8″W / 43.35778°N 72.25222°W[1]
General
Category	Phosphate minerals
Formula (repeating unit)	LiFe^2+PO4
Strunz classification	8.AB.10
Crystal system	Orthorhombic
Identification
Color	Green–blue gray, brown–black
Crystal habit	Massive, granular, prismatic
Crystal symmetry	Orthorhombic - dipyramidal H-M symbol: (2/m 2/m 2/m) Space group: Pmnb
Cleavage	{100} perfect, {010} imperfect, {011} poor
Fracture	Uneven–subconchoidal
Mohs scale hardness	4–5
Luster	Vitreous–subresinous
Streak	White–grayish white
Diaphaneity	Transparent–translucent
Optical properties	Biaxial (+), 2V = 0°–65°
Refractive index	nα=1.675–1.694, nβ=1.684–1.695, nγ=1.685–1.700
Birefringence	δ =0.0060–0.0080
References	[2][3][4]

Triphylite is a lithium iron(II) phosphate mineral with the chemical formula LiFe²⁺PO₄.^[5] It is a member of the triphylite group, and forms a complete solid solution series with the lithium manganese(II) phosphate, lithiophilite.

References

1. "Chandlers Mill Quarry, Newport, Sullivan Co., New Hampshire, USA". MinDat.org.
2. "Triphylite". WebMineral.com. Retrieved July 15, 2015.
3. "Triphylite". Mindat.org.
4. Anthony, John W.; Bideaux, Richard A.; Bladh, Kenneth W.; Nichols, Monte C. (eds.). "Triphylite" (PDF). Handbook of Mineralogy. Chantilly, VA: Mineralogical Society of America.
5. IMA-CNMNC List of Mineral Names (May 2015), International Mineralogical Association