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Narsarsukite  
Current inventory:  0 gems
 

  
Narsarsukite is named for the Greenland locality at Narssârssuk (Narsarsuk).

Discovered in 1900;   IMA status: Valid (IMA approved 1990)

Chemistry

Chemical Formula:

Na₂(Ti,Fe)Si₄(O,F)₁₁

Sodium Titanium Iron Silicate Fluoride

Molecular Weight:

387.19 gm

Composition:

Sodium

11.88 %

Na

16.01 %

Na₂O

Titanium

9.27 %

Ti

15.47 %

TiO₂

Iron

3.61 %

Fe

5.16 %

Fe₂O₃

Silicon

29.02 %

Si

62.07 %

SiO₂

Oxygen

41.32 %

O

Fluorine

4.91 %

F

4.91 %

F

  —   %

F

—2.07 %

—O=F₂

100.00 %

100.00 %

= TOTAL OXIDE

Classification

Mineral Classification:

Silicates (Germanates)

Strunz 8th Ed. ID:

8/F.34-10

Nickel-Strunz 10th Ed. ID:

9.DJ.05

9 : SILICATES (Germanates)
D : Inosilicates
J : Inosilicates with 4-periodic double and triple chains

Synonyms:

Goureite, Unnamed (MSH UK-2)

Crystal Data

Crystallography:

Tetragonal - Dipyramidal

Crystal Habit:

Crystals, commonly flat tabular to equant, rarely prismatic, striated || [001], to 3 cm. In divergent, radiating groups; as fine-grained segregations, massive.

Twinning:

None

Physical Properties

Cleavage:

{100} and {110}, Good

Fracture:

Uneven to Sub-Conchoidal

Tenacity:

Brittle

Moh's Hardness:

7.0

Density:

2.64 - 2.83 (g/cm³)

Luminescence:

None

Radioactivity:

Not Radioactive

Optical Properties

Color:

Honey-Yellow to Lemon-Yellow, Reddish Brown, Brownish Gray, Tan, Pink, may be zoned; Green from inclusions

Transparency:

Transparent to Translucent

Luster:

Vitreous, Pearly on {110}

Refractive Index:

1.601 - 1.655  Uniaxial ( + )

Birefringence:

0.0210

Dispersion:

Very high

Pleochroism:

Weak; O = colorless to yellow; E = colorless to honey-yellow

Occurances

Geological Setting:

In pegmatite (Narssârssuk, Greenland); in quartz veins in syenite intruding limestone (Sweetgrass Hills, Montana, USA); in hornfels, igneous breccia, and marble xenoliths in an intrusive alkalic gabbro-syenite complex (Mont Saint-Hilaire, Canada).

Common Associations:

Aegirine, microcline, albite, elpidite, epididymite, taeniolite, quartz (Narssârssuk, Greenland); aegirine, pectolite, calcite, feldspar, galena, quartz (Sweetgrass Hills, Montana, USA).

Type Locality:

Narssârssuk pegmatite (Narsarsuk pegmatite), Narssârssuk (Narsarsuk), Igaliku (Igaliko), Narsaq, Kitaa (West Greenland) Province, Greenland

Year Discovered:

1900 (IMA approved 1990)

View mineral photos:

Narsarsukite Mineral Photos and Locations

More Information

Mindat.org
Webmineral.com

Narsarsukite is a rare silicate mineral and gem that was described in 1900 from the locality at Narsarsuk, Greenland but not approved by the IMA until 1990. Narsarsuk is the result of agpaitic pegmatite intrusions, an unusual igneous rock that is high in alkaline metals such as sodium and poor in silica. These intrusions also contain a large number of unusual elements such as titanium, fluorine and rare earth metals. Narsarsukite is also found at Mont Saint-Hilaire (MSH), Quebec, Canada which is another agpaitic pegmatite location. MSH is probably the best location for fine Narsarsukite specimens with relatively large and well formed crystals. Narsarsukite may also include yttrium, calcium and potassium, but they are usually not significant enough to be included in the general formula.

Narsarsukite can be found at these locations: Narssârssuk; on the Island of Igdlutalik, in the Ilímaussaq intrusion; and in the Werner Berge complex, Greenland. On Mt. Flora, Lovozero massif, Kola Peninsula; in the Murun massif, southwest of Olekminsk, Yakutia; and other less-well-defined localities in Russia. In the Oslofjord, Norway. At the Bellerberg volcano, two km north of Mayen, Eifel district, Germany. From near Whitlash, Sweetgrass Hills, Sweetgrass County, Montana; in the Diamond Jo quarry, Magnet Cove, Hot Spring County, and from Granite Mountain, near Little Rock, Pulaski County, Arkansas, USA. At Mont Saint-Hilaire, Quebec, Canada. From Gouré, Damagaram, Niger. In the Sirwa massif, north of Ouarzazate, Morocco.
 

  
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