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| Melanite
is named from the Greek word "melan", meaning
black. Andradite is named for José Bonifácio de Andrada e Silva (1763-1838), Brazilian mineralogist.
| Discovery
year unknown;
IMA
status:
Not Valid (a variety of Andradite Garnet) |
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Chemistry
|
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Chemical
Formula: |
Ca3Fe3+2(SiO4)3
+
Ti |
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Calcium
Iron Titanium Silicate |
Molecular
Weight: |
508.18 gm
(Andradite) |
Composition: |
Calcium |
23.66 % |
Ca |
33.11 % |
CaO |
(based
on Andradite): |
Iron |
21.98 % |
Fe |
28.28 % |
FeO |
|
Silicon |
16.58 % |
Si |
35.47 % |
SiO2 |
|
Titanium |
?? % |
Ti |
?? % |
TiO2 |
|
Oxygen |
37.78 % |
O |
|
|
|
|
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/A.08-110
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Nickel-Strunz 10th
Ed. ID:
|
9.AD.25 |
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9 : SILICATES (Germanates) A : Nesosilicates D : Nesosilicates without additional anions; cations in [6] and/or greater coordination
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Related
to: |
Variety
of Andradite. Garnet Group. Andradite-Grossular Series.
Andradite-Schorlomite Series.
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Varieties: |
None
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Synonyms: |
Titanian
Adradite
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Crystal
Data
|
|
|
Crystallography:
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Isometric
- Hexoctahedral
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Crystal
Habit:
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Commonly well-crystallized dodecahedra, trapezohedra, or combinations, to 5 cm. Also granular to massive.
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Twinning:
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None
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Physical
Properties
|
|
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Cleavage: |
None
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Fracture: |
Irregular/Uneven,
Conchoidal
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Tenacity:
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Brittle
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Moh's
Hardness: |
6.5
- 7.0
|
Density:
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3.80 - 3.90 (g/cm3)
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Luminescence:
|
None
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Radioactivity:
|
Not
Radioactive
|
|
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Optical
Properties
|
|
|
Color: |
Black
|
Transparency: |
Opaque
|
Luster: |
Adamantine,
Resinous, Dull
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Refractive
Index: |
1.887 Isotropic
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Birefringence: |
0.000
(Isotropic)
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Dispersion: |
Andradite:
0.057
|
Pleochroism: |
None
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Anisotrophism: |
Typically
Weak
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Occurances
|
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Geological
Setting: |
In skarns from contact metamorphosed impure limestones or calcic igneous
rocks; in chlorite schists and serpentinites; in alkalic igneous rocks,
then typically titaniferous. |
Common
Associations: |
Chlorite Group,
Vesuvianite, Epidote, Spinel, Calcite, Dolomite, Magnetite
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Common
Impurities: |
Ti,
Cr, Al, Mg |
Type
Locality: |
Unknown.
Andradite: Drammen, Buskerud, Norway
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Year
Discovered: |
Unknown.
Andradite: 1868 |
View
mineral photos: |
Melanite
Mineral Photos and Locations |
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More
Information
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|
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Mindat.org
(Melanite) Mindat.org
(Andradite) Webmineral.com
(Andradite)
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Melanite
is a black, titanium-rich, variety of Andradite Garnet.
The Andradite variety of the Garnet Group of minerals
includes Melanite (black), Demantoid (green) and Topazolite
(yellow). Melanite's black color is due to its high
titanium content and is occassionally referred to as
"titanian adradite".
Although
there are many localities for Melanite, there are three
that are known for crystals large enough for faceting:
Nioro du Sahel Circle, Kayes Region, Mali; Chihuahua, Mexico;
Dallas Gem Mine (Benitoite
Mine), Diablo Range, San Benito County,
California, USA.
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Melanite
gems for sale:
We
have not photographed our Melanite gems. Please
check back soon.
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