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| Narsarsukite
is named for the Greenland locality at Narssârssuk (Narsarsuk).
| Discovered
in 1900;
IMA
status: Valid (IMA approved
1990) |
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Chemistry
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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 |
|
|
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Fluorine |
4.91 % |
F |
4.91 % |
F |
|
|
—
% |
F |
—2.07
% |
—O=F2 |
|
|
100.00 % |
|
100.00 % |
= TOTAL OXIDE |
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Classification
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Mineral
Classification: |
Silicates
(Germanates)
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Strunz 8th
Ed. ID:
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8/F.34-10
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Nickel-Strunz 10th
Ed. ID:
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9.DJ.05
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9 : SILICATES (Germanates) D : Inosilicates J : Inosilicates with 4-periodic double and triple chains
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Synonyms: |
Goureite,
Unnamed (MSH UK-2)
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Crystal
Data
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Crystallography:
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Tetragonal
- Dipyramidal
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Crystal
Habit:
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Crystals,
commonly flat tabular to equant, rarely prismatic, striated
|| [001], to 3 cm. In divergent, radiating groups;
as fine-grained segregations, massive.
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Twinning:
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None
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Physical
Properties
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Cleavage: |
{100}
and {110}, Good
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Fracture: |
Uneven
to Sub-Conchoidal
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Tenacity:
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Brittle
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Moh's
Hardness: |
7.0
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Density:
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2.64
- 2.83 (g/cm3)
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Luminescence:
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None
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Radioactivity:
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Not
Radioactive
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Optical
Properties
|
|
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Color: |
Honey-Yellow
to Lemon-Yellow, Reddish Brown, Brownish Gray, Tan,
Pink, may be zoned; Green from inclusions
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Transparency: |
Transparent
to Translucent
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Luster: |
Vitreous,
Pearly on {110}
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Refractive
Index: |
1.601
- 1.655 Uniaxial ( + )
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Birefringence: |
0.0210
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Dispersion: |
Very
high
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Pleochroism: |
Weak;
O
= colorless to yellow; E
= colorless to honey-yellow
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Occurances
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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 |
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More
Information
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|
Mindat.org
Webmineral.com
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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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