Classification
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Mineral
Classification: |
Oxides
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Strunz 8th
Ed. ID:
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4/D.15-20
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Nickel-Strunz 10th
Ed. ID:
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4.DB.25
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4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites,
bismuthites, sulfites, selenites, tellurites, iodates) D : Metal: Oxygen =
1:2 and similar B : With medium-sized cations; chains of edge-sharing
octahedra
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Related
to: |
Samarskite
Group. Brookite - Kuranakhite Series
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Members
of Group: |
Samarskite
Group: Calciosamarskite,
Ishikawaite, Samarskite-(Y), Samarskite-(Yb), Srilankite
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Varieties: |
None
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Synonyms: |
ICSD 69619,
IMA1982-056, PDF 46-1265
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Crystal
Data
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Crystallography:
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Orthorhombic - Dipyramidal
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Crystal
Habit:
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Tabular crystals, often twinned.
As idiomorphic inclusions, less than 1 mm, intergrown
with associated minerals.
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Twinning:
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Interpenetration and contact twins.
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Physical
Properties
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Cleavage: |
Poor/indistinct
in one direction
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Fracture: |
Conchoidal
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Tenacity:
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Brittle
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Moh's
Hardness: |
~6.5; Vickers: VHN100=900-1000 kg/mm2
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Density:
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~4.60 (g/cm3)
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Luminescence:
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None
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Radioactivity:
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Generally
not
radioactive but may be anomalously radioactive.
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Optical
Properties
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Color: |
Black,
brownish black; dark blue in transmitted light; gray-white
in reflected light.
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Transparency: |
Opaque,
translucent in thin fragments. |
Luster: |
Sub-metallic
to adamantine
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Refractive
Index: |
2.380
Biaxial ( - )
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Birefringence: |
0.000
(Isotropic)
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Dispersion: |
n/a |
Pleochroism: |
None |
Anisotropism: |
Observed;
internal reflections:
brown, dark blue
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Occurances
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Geological
Setting: |
In
pebbles found in concentrates from a placer gemstone
mine. |
Common
Associations: |
Zirconolite,
Baddeleyite, Geikielite, Spinel, Perovskite |
Common
Impurities: |
n/a
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Type
Locality: |
Rakwana, Sabaragamuwa Province, Sri Lanka
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Year
Discovered: |
1982;
IMA approved 1983 |
View
mineral photos: |
n/a
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More
Information
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Mindat.org
Webmineral.com
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Srilankite
is a very rare titanium
zirconium oxide mineral. It
is a member of the Samarskite
Group of minerals that also includes Samarskite-(Y).
Srilankite is usually found as minute inclusions (less than
1 mm) in other associated minerals. Independent crystals
do exist but are extremely rare so gems are even rarer.
Crystals are typically opaque, black to dark brownish
black with sub-metallic to adamantine luster.
Srilankite was
named in 1983 by Alexander Willgallis, Eveline Siegmann, and Theja
Hettiaratchi after its discovery locality at Rakwana, Sabaragamuwa
Province, Sri Lanka. This is also the only locality in
the world where Srilankite has been found.
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