Vesuvianite

Silicate mineral
(repeating unit)Ca10(Mg, Fe)2Al4(SiO4)5(Si2O7)2(OH,F)4IMA symbolVes[1]Strunz classification9.BG.35Crystal systemTetragonalCrystal classDitetragonal dipyramidal (4/mmm)
H-M symbol: (4/m 2/m 2/m)Space groupP4/nncUnit cella = 15.52 Å, c = 11.82 Å
Z = 2IdentificationColorYellow, green, brown; colorless to white, brown-black, light green, emerald green, violet, blue-green to blue, pink, purple, red, black, commonly zonedCrystal habitShort pyramidal to long prismatic crystals common, massive to columnarTwinningFine twin domains observedCleavagePoor on {110} and {100} very poor on {001}FractureSub conchoidal to irregularTenacityBrittleMohs scale hardness6–7LusterVitreous to resinousStreakWhiteDiaphaneitySubtransparent to translucentSpecific gravity3.32–3.43Optical propertiesUniaxial (−)Refractive indexnω = 1.703–1.752
nε = 1.700–1.746Birefringence0.004–0.006Pleochroismslight in colored varietiesSolubilityVesuvianite is virtually insoluble in acidsOther characteristicsstriated lengthwiseReferences[2][3][4]

Vesuvianite, also known as idocrase, is a green, brown, yellow, or blue silicate mineral. Vesuvianite occurs as tetragonal crystals in skarn deposits and limestones that have been subjected to contact metamorphism.[3] It was first discovered within included blocks or adjacent to lavas on Mount Vesuvius, hence its name. Attractive-looking crystals are sometimes cut as gemstones. Localities which have yielded fine crystallized specimens include Mount Vesuvius and the Ala Valley near Turin, Piedmont.[5]

The specific gravity is 3.4 and the Mohs hardness is 6+1⁄2. The name "vesuvianite" was given by Abraham Gottlob Werner in 1795, because fine crystals of the mineral are found at Vesuvius; these are brown in color and occur in the ejected limestone blocks of Monte Somma. Several other names were applied to this species, one of which, "idocrase" by René Just Haüy in 1796, is now in common use.[5]

A sky bluish variety known as cyprine has been reported from Franklin, New Jersey and other locations; the blue is due to impurities of copper in a complex calcium aluminum sorosilicate. Californite is a name sometimes used for jade-like vesuvianite, also known as California jade, American jade or Vesuvianite jade. Xanthite is a manganese rich variety. Wiluite is an optically positive variety from Wilui, Siberia. Idocrase is an older synonym sometimes used for gemstone-quality vesuvianite. Also, Vessonite and Vassolite are variant spellings commonly encountered in the gem trade.

References

  1. ^ 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.
  2. ^ Mindat with location data
  3. ^ a b Handbook of Mineralogy
  4. ^ https://www.mineralienatlas.de/lexikon/index.php/MineralData?mineral=Vesuvianite Mineralienatlas
  5. ^ a b  One or more of the preceding sentences incorporates text from a publication now in the public domain: Spencer, Leonard James (1911). "Vesuvianite". In Chisholm, Hugh (ed.). Encyclopædia Britannica. Vol. 27 (11th ed.). Cambridge University Press. p. 1063.

Additional sources

  • Deere, W. A.; et al. (1962). Rock Forming Minerals. Vol. 1. pp. 113–120.
  • Webmineral data
  • Vesuvianite at Franklin-Sterling
  • Mindat - Cyprine variants with location data
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