Triplite

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Triplite
Triplite-t5105a.jpg
Triplite from Alchuri, Shigar Valley, Baltistan, Pakistan (1.2 x 1 x 0.9 cm)
General
Category Phosphate minerals
Formula
(repeating unit)
(Mn,Fe)2(PO4)(F,OH)
Strunz classification 08.BB.10
Crystal symmetry Monoclinic 2/m
Unit cell a = 11.97 Å, b = 6.52 Å, c = 10.09 Å; β = 105.62°; Z = 8
Identification
Color Chestnut to reddish brown, flesh-red, salmon-pink
Crystal habit Prismatic, massive to nodular
Crystal system Monoclinic
Cleavage Good on {001}, fair on {010}, poor on {100}
Fracture Uneven to subconchoidal
Mohs scale hardness 5 to 5.5
Luster Vitreous to resinous
Streak White to brown
Diaphaneity Translucent to opaque
Specific gravity 3.5 - 3.9
Optical properties Biaxial (+)
Refractive index nα=1.643–1.684, nβ=1.647–1.693, nγ=1.668–1.703
Pleochroism Distinct; yellow-brown to reddish brown
2V angle 25 - 76°
Dispersion r > v, moderate to strong
Alters to Alters to brownish black
References [1][2][3]

Triplite is a rare phosphate mineral with formula: (Mn,Fe)2PO4(F,OH). It occurs in phosphate-rich granitic pegmatites typically as irregular brown opaque masses. Triplite was first described in 1813 for an occurrence in Chanteloube, Limousin, France.[4] The name is from the Greek triplos for triple, in reference to the three cleavage directions.[2] In color and appearance, it is very similar to rhodocrosite, another manganese bearing mineral. Chemically, it is also quite similar to triploidite the difference being that triplite is fluorine dominant while triploidite is hydroxide dominant.

Occurrence[edit]

Triplite from Colorado

Triplite is a rare fluoro-hydroxide phosphate mineral that forms in phosphate rich granite pegmatites and high temperature hydrothermal veins. It has been found in the United States in California, Nevada, Arizona, Colorado, South Dakota, Virginia, Connecticut, and Maine. Other occurrences include the Shigar Valley, Pakistan; China; Bavaria, Germany; Kimito, Finland and Karibib, Namibia.[2]

References[edit]

  1. ^ Handbook of Mineralogy
  2. ^ a b c Mindat.org
  3. ^ Webmineral data
  4. ^ Triplite Crystals from Colorado, C. W. Wolf and E. Wm. Heinrich, American Mineralogist, Volume 32, pages 518-526, 1947

External links[edit]

Media related to Triplite at Wikimedia Commons