Kaersutite

Calcic titanium bearing amphibole mineral
(repeating unit)NaCa2(Mg3Ti4+Al)(Si6Al2)O22(O)2IMA symbolKrs[1]Strunz classification9.DE.10Dana classification66.01.03a.18Crystal systemMonoclinicCrystal classPrismatic (2/m)
(same H-M symbol)Space groupC2/mIdentificationColorDark brown to black, yellow-brown, green-brown, or red-brown in thin sectionCrystal habitPrismatic phenocrysts, granular aggregatesTwinningSimple or multiple twinning parallel to {100}CleavagePerfect on {110}, intersecting at 56° and 124°TenacityBrittleMohs scale hardness5–6LusterVitreousStreakPale brownish-greyDiaphaneitySemitransparentSpecific gravity3.20 - 3.28Optical propertiesBiaxial (−)Refractive indexnα = 1.670 – 1.689 nβ = 1.690 – 1.741 nγ = 1.700 – 1.772Birefringenceδ = 0.030 – 0.083PleochroismStrong; X = yellow, yellow-brown; Y = red, red-brown; Z = deep brown, dark red-brown.2V angle66–82°References[2][3][4][5]

Kaersutite is a dark brown to black double chain calcic titanium bearing amphibole mineral with formula: NaCa2(Mg3Ti4+Al)(Si6Al2)O22(O)2.[6]

Ferro-kaersutite is the divalent iron rich endmember of the kaersutite group, with the iron replacing magnesium in the structure.[7]

It occurs as phenocrysts in alkalic volcanic rocks; in nodules of peridotite and gabbro in alkalic basalts; in syenites, monzonites and carbonatite tuffs. Mineral association includes titanian augite, rhoenite, olivine, ilmenite, spinel, plagioclase and titanian pargasite.[2]

It was first described in 1884 and is named for Qaersut (formerly Kaersut), Umanq district in northern Greenland.[3]

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. ^ a b "Kaersutite" (PDF). Handbook of Mineralogy. Retrieved 2024-03-21.
  3. ^ a b http://www.mindat.org/min-2129.html Mindat: Kaersutite
  4. ^ http://www.webmineral.com/data/Kaersutite.shtml Webmineral data
  5. ^ "IMA Master List". Archived from the original on 2015-01-05. Retrieved 2014-05-12.
  6. ^ http://www.minsocam.org/msa/ammin/toc/Abstracts/2012_Abstracts/ND12_Abstracts/Hawthorne_p2031_12.pdf
  7. ^ Ferro-kaersutite on Mindat


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