Triphylite

Source: Wikipedia, the free encyclopedia.
Mohs scale hardness
4–5
LusterVitreous–subresinous
StreakWhite–grayish white
DiaphaneityTransparent–translucent
Optical propertiesBiaxial (+), 2V = 0°–65°
Refractive indexnα=1.675–1.694, nβ=1.684–1.695, nγ=1.685–1.700
Birefringenceδ =0.0060–0.0080
References[3][4][5]

Triphylite is a lithium iron(II)

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.[7][8] The name derives from the Greek words tri ("three") and phulon ("family"), referring to the three cations found in natural samples of triphylite (Li+, Fe2+, Mn2+).[5]

Crystal structure

Crystal structure of triphylite

Triphylite crystallizes in an orthorhombic crystal system. The lithium coordinates to six oxygen atoms in a distorted octahedron. Likewise, the iron centers are octahedrally coordinated. The structure contains isolated phosphate tetrahedra.[9]

Properties

Triphylite is soluble in

hydrochloric and sulfuric acid. Under a blowpipe, it melts to form a dark gray, magnetic ball.[7] Over time, the mineral undergoes alteration by oxidation, increasing the oxidation state of iron from +2 to +3 and allowing the lithium to escape, forming heterosite, FePO4.[8]

Triphylite forms a complex solution series with lithiophilite, LiMnPO4, so that natural sources of triphylite usually contain manganese. The structures of members within this series are similar to olivine-type silicates.[10]

References

  1. ^ "Chandlers Mill Quarry, Newport, Sullivan Co., New Hampshire, USA". MinDat.org.
  2. S2CID 235729616
    .
  3. ^ "Triphylite". WebMineral.com. Retrieved July 15, 2015.
  4. ^ "Triphylite". Mindat.org.
  5. ^ a b Anthony, John W.; Bideaux, Richard A.; Bladh, Kenneth W.; Nichols, Monte C. (eds.). "Triphylite" (PDF). Handbook of Mineralogy. Chantilly, VA: Mineralogical Society of America.
  6. ^ IMA-CNMNC List of Mineral Names (May 2015), International Mineralogical Association
  7. ^ ..
  8. ^ ..
  9. ^ "Triphylin". Römpp Online. Retrieved 2020-06-13.
  10. ^ "Lithiophite-Triphylite Series". Mindat.org.