.mw-parser-output .hidden-begin{box-sizing:border-box;width:100%;padding:5px;border:none;font-size:95%}.mw-parser-output .hidden-title{font-weight:bold;line-height:1.6;text-align:left}.mw-parser-output .hidden-content{text-align:left}@media all and (max-width:500px){.mw-parser-output .hidden-begin{width:auto!important;clear:none!important;float:none!important))You can help expand this article with text translated from the corresponding article in German. (July 2015) Click [show] for important translation instructions. View a machine-translated version of the German article. Machine translation, like DeepL or Google Translate, is a useful starting point for translations, but translators must revise errors as necessary and confirm that the translation is accurate, rather than simply copy-pasting machine-translated text into the English Wikipedia. Consider adding a topic to this template: there are already 1,897 articles in the main category, and specifying|topic= will aid in categorization. Do not translate text that appears unreliable or low-quality. If possible, verify the text with references provided in the foreign-language article. You must provide copyright attribution in the edit summary accompanying your translation by providing an interlanguage link to the source of your translation. A model attribution edit summary is Content in this edit is translated from the existing German Wikipedia article at [[:de:Triphylin]]; see its history for attribution. You may also add the template ((Translated|de|Triphylin)) to the talk page. For more guidance, see Wikipedia:Translation.
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 / 43.35778; -72.25222[1]
CategoryPhosphate minerals
(repeating unit)
IMA symbolTrp[2]
Strunz classification8.AB.10
Crystal systemOrthorhombic
Crystal classDipyramidal (mmm)
H-M symbol: (2/m 2/m 2/m)
Space groupPmnb
Unit cella = 6.0285(6) Å, b = 10.3586(9) Å, c = 4.7031(3) Å, Z = 4
ColorGreen–blue gray, brown–black
Crystal habitMassive, granular, prismatic
Cleavage{100} perfect, {010} imperfect, {011} poor
Mohs scale hardness4–5
StreakWhite–grayish white
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

Triphylite is a lithium iron(II) phosphate mineral with the chemical formula LiFePO4.[6] It is a member of the triphylite group and forms a complete solid solution series with the lithium manganese(II) phosphate, lithiophilite. Triphylite crystallizes in the orthorhombic crystal system. It rarely forms prismatic crystals and is more frequently found in 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]


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]


  1. ^ "Chandlers Mill Quarry, Newport, Sullivan Co., New Hampshire, USA". MinDat.org.
  2. ^ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. 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. ^ a b von Fuchs, Johann Nepomuk (1834). "Ueber ein neues Mineral (Triphylin)". Journal für Praktische Chemie. 3: 98–104. doi:10.1002/prac.18340030120..
  8. ^ a b von Fuchs, Johann Nepomuk (1835). "Vermischte Notizen, 3. Triphylin". Journal für Praktische Chemie. 5: 319. doi:10.1002/prac.18350050138..
  9. ^ "Triphylin". Römpp Online. Retrieved 2020-06-13.
  10. ^ "Lithiophite-Triphylite Series". Mindat.org.