Kaersutite
| Kaersutite | |
|---|---|
| General | |
| Category | Inosilicate |
| Formula (repeating unit) | NaCa2(Mg3Ti4+Al)(Si6Al2)O22(OH)2 |
| Strunz classification | 09.DE.10 |
| Dana classification | 66.01.03a.18 |
| Crystal system | Monoclinic - prismatic (2/m) |
| Identification | |
| Color | Dark brown to black - yellow-brown, green-brown, or red-brown in thin section |
| Crystal habit | Prismatic phenocrysts, granular aggregates |
| Twinning | Simple or multiple twinning parallel to {100} |
| Cleavage | Perfect on {110}, intersecting at 56° and 124° |
| Tenacity | Brittle |
| Mohs scale hardness | 5 - 6 |
| Luster | Vitreous |
| Streak | Pale brownish-grey |
| Diaphaneity | Semitransparent |
| Specific gravity | 3.20 - 3.28 |
| Optical properties | Biaxial (-) |
| Refractive index | nα = 1.670 - 1.689 nβ = 1.690 - 1.741 nγ = 1.700 - 1.772 |
| Birefringence | δ = 0.030 - 0.083 |
| Pleochroism | Strong; X = yellow, yellow-brown; Y = red, red-brown; Z = deep brown, dark red-brown. |
| 2V angle | 66 - 82° |
| References | [1][2][3][4] |
Kaersutite is a dark brown to black double chain calcic titanium bearing amphibole mineral with formula: NaCa2(Mg3Ti4+Al)(Si6Al2)O22(OH)2.
Ferro-kaersutite is the divalent iron rich endmember of the kaersutite group, with the iron replacing magnesium in the structure.[5]
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.[1]
It was first described in 1884 and is named for Qaersut (formerly Kaersut), Umanq district in northern Greenland.[2]
References
- ^ a b http://rruff.geo.arizona.edu/doclib/hom/kaersutite.pdf Handbook of Mineralogy
- ^ a b http://www.mindat.org/min-2129.html Mindat: Kaersutite
- ^ http://www.webmineral.com/data/Kaersutite.shtml Webmineral data
- ^ IMA Master List
- ^ Ferro-kaersutite on Mindat
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