Kaersutite
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Kaersutite was named by Johannes Theodor Lorenzen (1855-1884), Danish mineralogist interested in Greenland minerals, for the locality at Qaersut (Kaersut), Uummannaq, northern Greenland where it was discovered in 1884.

Discovered in 1884. IMA status: Valid (pre-IMA; Grandfathered)

Chemistry

Chemical Formula:

NaCa₂[(Mg;Fe²⁺)₄Ti](Si₆Al₁₂)O₂₂(OH)₂  

Sodium Calcium Magnesium Titanium Aluminum Silicate Hydroxide

Molecular Weight:

872.72 gm

Composition:

Sodium

2.63 %

Na

3.55 %

Na₂O

Calcium

9.18 %

Ca

12.85 %

CaO

Magnesium

11.14 %

Mg

18.47 %

MgO

Titanium

5.49 %

Ti

9.15 %

TiO₂

Aluminum

6.18 %

Al

11.68 %

Al₂O₃

Silicon

19.31 %

Si

41.31 %

SiO₂

Hydrogen

0.23 %

H

2.06 %

H₂O

Oxygen

45.83 %

O

100.00 %

98.08 %

= TOTAL OXIDE

Classification

Mineral Classification:

Silicates (Germanates)

Strunz 8th Ed. ID:

8/F.10-150

Nickel-Strunz 10th Ed. ID:

9.DE.15

9 : SILICATES (Germanates)
D : Inosilicates
E : Inosilicates with 2-periodic double chains, Si₄O₁₁; Clinoamphiboles

Related to:

Kaersutite Root Name Group. w(O)-dominant Amphibole Group. Amphibole Supergroup. Ferrokaersutite-Kaersutite Series.

Varieties:

Linosite

Synonyms:

ICSD 67049, Oxykaersutite, PDF 44-1450

Crystal Data

Crystallography:

Monoclinic - Prismatic

Crystal Habit:

Commonly as well-formed phenocrysts with rhombic basal sections; prismatic, to 10 cm; as granular aggregates.

Twinning:

Simple or multiple twinning || {100}.

Physical Properties

Cleavage:

Perfect on {110}, intersecting at 56° and 124°; partings on {100}, {001}.

Fracture:

Conchoidal

Tenacity:

Brittle

Moh's Hardness:

5.0 - 6.0

Density:

3.20 - 3.28 (g/cm³)

Luminescence:

None

Radioactivity:

Not Radioactive

Optical Properties

Color:

Dark Brown to Black, typically zoned; Yellow-Brown, Green-Brown, or Red-Brown in thin section.

Transparency:

Translucent to Subopaque

Luster:

Vitreous, Resinous

Refractive Index:

1.670 - 1.772  Biaxial  ( - )

Birefringence:

0.030 - 0.083

Dispersion:

Strong; r > v

Pleochroism:

Strong; X = yellow, yellow-brown; Y = red, red-brown; Z = deep brown, dark red-brown.

Occurances

Geological Setting:

Common as phenocrysts in alkalic volcanic rocks; in gabbroic and peridotitic nodules in alkalic basalts; in syenites, monzonites, carbonatite tuffs, and alkalic gabbros.

Common Associations:

Ilmenite, Olivine, Plagioclase, Rhönite, Spinel, Titanian Augite, Titanian Pargasite

Common Impurities:

Fe, Mn, K, F, H₂O

Type Locality:

Qaersut (Kaersut), Uummannaq (Umanak) Firth, Kitaa (West Greenland) Province, Greenland

Year Discovered:

1884

View mineral photos:

Kaersutite Mineral Photos and Locations

More Information

Mindat.org
Webmineral.com

Kaersutite is a rare titanium bearing member of the Calcic Clino-Amphibole Subgroup of the Amphibole Group of minerals that includes Actinolite, Ferro-edenite, Kaersutite, Pargasite, Richterite and Tremolite. The Amphibole Group is an extensive and complex group of minerals currently divided into several sub-groups. Kaersutite occurs in intermediate alkali igneous rocks and is one of the rock-forming amphiboles typically found in nepheline syenite. Crystals are commonly very dark brown to black, well-formed, prismatic phenocrysts to about 10 cm with vitreous luster.

Kaersutite was named for the locality at Qaersut (Kaersut), Uummannaq, northern Greenland where it was discovered in 1884. It was named by Johannes Theodor Lorenzen (1855-1884), Danish mineralogist interested in Greenland minerals. Lorenzen died at age 29 while on an expedition to Greenland in 1884. The mineral Lorenzenite was named in his honor.

Kaersutite is found In Greenland, from Østerfjeld, near Qaersut, at Nûgssuaq, and elsewhere in the Kangerdlugssuaq Fjord and Skaergaard areas; on Linosa, Pelagian Islands, south of Sicily, Italy; from Vlcí Hora (Wolf Hill) , Cernošín, Czech Republic; near Boulder Dam, Mohave County, and near San Carlos, Gila County, Arizona, USA; Mont Saint-Hilaire, Quebec, Canada; Chikaishi, Oki Island, Shimane Prefecture, and at Mushozu and Numazu, Iki Island, Nagasaki Prefecture, Japan; at Kakanui, New Zealand. A number of other localities are known.
 

  
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