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| Chemistry:
KNa2(Fe3+Mn3+Al)2Li3Si12O30 [Potassium Sodium Lithium Iron Manganese Aluminum Silicate] | Discovered
in 1944;
IMA
status: Valid (IMA approved 1976). Sugilite
is named after Ken-ichi Sugi (1901-1948), Japanese petrologist
who discovered it. |
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Classification
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Mineral
Classification: |
Silicates |
Strunz 8th
Ed. ID:
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8/E.22-110
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Nickel-Strunz 10th
Ed. ID:
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9.CM.05 |
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9 : SILICATES (Germanates) C : Cyclosilicates M :
[Si6O18]12- 6-membered double rings
(sechser-Doppelringe)
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Related
to: |
Osumilite
Group. Millarite - Osumilite Series.
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Crystal
Data
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Crystallography:
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Hexagonal
- Dihexagonal Dipyramidal
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Crystal
Habit:
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Crystals
prismatic, to 2 cm, rare. Commonly in interlocking aggregates
of subhedral grains, compact to massive.
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Twinning:
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None
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Physical
Properties
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Cleavage: |
[0001]
Indistinct/Poor
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Fracture: |
Irregular/Uneven
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Tenacity:
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Brittle
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Hardness
(Mohs): |
6.0 -
6.5
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Density:
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2.74
- 2.79 (g/cm3)
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Luminescence:
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None |
Radioactivity:
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Barely
Detectable;
GRapi = 54.07 (Gamma Ray American Petroleum Institute Units)
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Optical
Properties
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Color: |
Light
Brownish Yellow, Lavender, intense Reddish Violet, bright
Magenta, Purplish, dark Rose Red
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Transparency: |
Translucent
to Transparent |
Luster: |
Vitreous |
Refractive
Index: |
1.595
- 1.611 Uniaxial ( - )
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Birefringence: |
0.0030
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Dispersion: |
n/a |
Pleochroism: |
Weak |
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Occurances
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Geological
Setting: |
In
an aegirine-bearing syenite stock in biotite granite
(Iwagi Islet, Japan); in bedded manganese deposits (near
Kuruman, South Africa). |
Common
Associations: |
Aegirine,
Albite, Allanite, Andradite, Apatite, Pectolite, Titanite,
Zircon, (Iwagi Islet, Japan) |
Common
Impurities: |
Ti,
H2O |
Type
Locality: |
Iwagi Island, Inland Sea (Setonaikai), Ehime Prefecture,
Japan |
Year
Discovered: |
1944;
IMA approved 1976
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View
mineral photos: |
Sugilite
Mineral Photos and Locations |
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More
Information
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Mindat.org Webmineral.com |
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Sugilite
was originally discovered in 1944 by Japanese geologist
Ken-ichi Sugi on Iwagi Island, Japan as very tiny yellowish
crystals. It wasn't until 1975, when a thin seam of
purplish Sugilite was found in a core sample in the
Kuruman manganese fields of South Africa. In 1979 a
huge mass, as much as 10-12 tons, of Sugilite was discovered
at a depth of 3,200 feet at this location. Only half of this material
had the fine grape jelly color that is highly desired.
Of this, a tiny percentage (maybe 0.1%) is translucent.
Some transparent Sugilite has been cut into gems, but
these are very rare. Sugilite has become very popular
in the jewelry trade as cabochons and carvings. It has
been described as a purple Turquoise
although
there is no relation between the two minerals.
Sugilite
is found in just a few locations worldwide including
Liguria, and Tuscany Italy; Iwagi Island, Japan (Type
Location); Wessels Mine, Hotazel, Kalahari
manganese fields, Northern Cape Province, South Africa.
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Sugilite
gems for sale:
We
have not photographed our Sugilite
gems. Please
check back soon.
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