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
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| General | |
|---|---|
| Category | Phosphate minerals |
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Formula (repeating unit) |
LiFe2+PO4 |
| Strunz classification | 8.AB.10 |
| Crystal system | Orthorhombic |
| Crystal class | Dipyramidal (mmm) H-M symbol: (2/m 2/m 2/m) |
| Space group | Pmnb |
| Identification | |
| Color | Green–blue gray, brown–black |
| Crystal habit | Massive, granular, prismatic |
| 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 | |
Triphylite is a lithium iron(II) phosphate mineral with the chemical formula LiFe2+PO4. It is a member of the triphylite group, and forms a complete solid solution series with the lithium manganese(II) phosphate, lithiophilite.
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