Arfvedsonite

Sodium amphibole mineral
(repeating unit)[Na][Na2][(Fe2+)4Fe3+][(OH)2|Si8O22]IMA symbolArf[1]Strunz classification9.DE.25 (10 ed)
VIII/F.08-100 (8 ed)Dana classification66.1.3c.9Crystal systemMonoclinicCrystal classPrismatic (2/m)
(same H-M symbol)Space groupC2/mIdentificationColorBlack, deep green on thin edgesCrystal habitFibrous, radial prismatic aggregatesTwinningSimple or lamellar parallel to [100]CleavagePerfect on [110]FractureUnevenTenacityBrittleMohs scale hardness5–6LusterVitreousStreakDeep bluish gray, gray-greenDiaphaneityTranslucent to opaqueSpecific gravity3.3–3.5Optical propertiesBiaxial (−)Refractive indexnα = 1.652–1.699
nβ = 1.660–1.705
nγ = 1.666–1.708Birefringenceδ = 0.014PleochroismStrong: Blue-greens, yellow-browns, gray-violetsDispersionr > v strongReferences[2][3][4][5]

Arfvedsonite (/ˈɑːrvɛdsənaɪt/[6]) or soda hornblende (partiellement obsolète) is a sodium amphibole mineral with composition: [Na][Na2][(Fe2+)4Fe3+][(OH)2|Si8O22]. It crystallizes in the monoclinic prismatic crystal system and typically occurs as greenish black to bluish grey fibrous to radiating or stellate prisms.

It is a rather rare mineral occurring in nepheline syenite intrusions and agpaitic (peralkaline) pegmatites and granites as the Golden Horn batholith in Okanogan County, Washington (type locality for zektzerite). Occurrences include Mont Saint-Hilaire, Quebec, Canada; the Ilímaussaq complex in Southern Greenland; and in pegmatites of the Kola Peninsula, Russia. Its mineral association includes nepheline, albite, aegirine, riebeckite, katophorite and quartz.[2]

Arfvedsonite was discovered in 1823 and named for the Swedish chemist Johan August Arfwedson (1792–1841).[4]

See also

Arfvedsonite, Poudrette quarry, Mont Saint-Hilaire, Montérégie, Quebec

References

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  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 Arfvedsonite. Handbook of Mineralogy
  3. ^ Arfvedsonite. Mindat.org
  4. ^ a b Arfvedsonite. Webmineral
  5. ^ "IMA Master List". Archived from the original on 2015-01-05. Retrieved 2014-05-12.
  6. ^ "arfvedsonite". The Chambers Dictionary (9th ed.). Chambers. 2003. ISBN 0-550-10105-5.
  • Deer, W.A., R.A. Howie, and J. Zussman (1963) Rock-forming Minerals, v. 2, Chain Silicates, p. 364–374
  • Mineral Galleries