Lithiophilite

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Lithiophilite
Lithiophilite with pyrolusite and quartz Lithium manganese phosphate Midnight Owl Mine, White Picacho District, near Wickenburg, Arizona 2793.jpg
Lithiophilite from the White Picacho District, Arizona
General
Category Phosphate minerals
Formula
(repeating unit)
LiMnPO4
Strunz classification 08.AB.10
Identification
Color Clove-brown, yellowish brown, honey-yellow, salmon-pink, blue-gray, gray
Crystal habit Prismatic – crystals shaped like slender prisms
Crystal system Orthorhombic (2/m 2/m 2/m) Space Group: Pmnb
Twinning Rare contact twins on {130}
Cleavage [100] perfect, [110] and [011] poor
Fracture uneven to conchoidal
Mohs scale hardness 4–5
Luster Vitreous to subresinous
Streak White to grayish white
Diaphaneity Transparent to translucent
Specific gravity 3.445–3.50
Optical properties Biaxial (+), 2V = 65°
Refractive index nα=1.669, nβ=1.673, nγ=1.682
Birefringence δ =0.0130
Pleochroism None to weak
References [1][2][3]

Lithiophilite is a mineral containing the element lithium. It is lithium manganese(II) phosphate with formula: LiMnPO4. It occurs in pegmatites often associated with triphylite, the iron end member in a solid solution series. The mineral with intermediate composition is known as sicklerite (Li(Mn,Fe)PO4). The name lithiophilite is derived from the Greek philos (φιλός) "friend," as lithiophilite is usually found with lithium.[2]

Lithiophylite is a resinous reddish to yellowish brown mineral crystallizing in the orthorhombic system often as slender prisms. It is usually associated with lepidolite, beryl, quartz, albite, amblygonite, and spodumene of pegmatitic origin. It rather readily weathers to a variety of secondary manganese phosphates and oxides. It is a late-stage mineral in some complex granite pegmatites.[3] Members of the triphylite-lithiophilite series readily alter to secondary minerals.

The type locality is the Branchville Quarry, Branchville, Fairfield County, Connecticut where it was first reported in 1878.[2] The largest documented single crystal of lithiophilite was found in New Hampshire, US, measured 2.44×1.83×1.22 m3 and weighed ~20 tonnes.[4]

The synthetic form of triphylite, lithium iron phosphate, is a promising material for the production of lithium-ion batteries.

References[edit]

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Lithiophilite, well-defined crystals to 3 cm, stacked en echelon in matrix. Locality: Emmons Quarry, Uncle Tom Mtn. Greenwood, Maine, USA