Acuminite

Rare halide mineral
(repeating unit)SrAlF4OH·(H2O)IMA symbolAcu[1]Strunz classification3.CC.10Crystal systemMonoclinicCrystal classPrismatic (2/m)
(same H-M symbol)Space groupC2/cUnit cella = 13.223, b = 5.175
c = 14.251 [Å]; β = 11.61°; Z = 8IdentificationColorWhiteCrystal habitClusters of acute dipyramidal Spearhead shaped crystalsTwinningContact on {100}CleavagePerfect on {001}Mohs scale hardness3.5LusterVitreousDiaphaneityTransparentSpecific gravity3.295Optical propertiesBiaxial (+)Refractive indexnα = 1.451 nβ = 1.453 nγ = 1.462 - 1.463References[2][3][4]

Acuminite is a rare halide mineral with chemical formula: SrAlF4(OH)·(H2O). Its name comes from the Latin word acumen, meaning "spear point". Its Mohs scale rating is 3.5.

Acumenite has only been described from its type locality of the cryolite deposit in Ivigtut, Greenland.[2]

See also

References

Look up acuminite in Wiktionary, the free dictionary.
  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. ^ a b Handbook of Mineralogy
  3. ^ Mindat.org
  4. ^ Webmineral data


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