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| Bementite
is named for Clarence Sweet Bement [1843-1923] by George Augustus Koenig
in 1887. Bement had a keen interest in Franklin,
New Jersey minerals from whence his namesake was discovered.
| Discovered
in 1887;
IMA
status: Valid (IMA approved 1963) |
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Chemistry
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Chemical
Formula: |
Mn5Si4O10(OH)6
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Manganese
Silicate Hydroxide |
Molecular
Weight: |
1,018.08 gm
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Composition: |
Manganese |
43.17 % |
Mn |
55.74 % |
MnO |
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Silicon |
16.55 % |
Si |
35.41 % |
SiO2 |
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Hydrogen |
0.99 % |
H |
8.85 % |
H2O |
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Oxygen |
39.29 % |
O |
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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/H.28-90
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Nickel-Strunz 10th
Ed. ID:
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9.EE.05
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9 : SILICATES (Germanates)
E : Phyllosilicates E : Single tetrahedral nets of 6-membered rings connected by octahedral nets or octahedral bands
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Related
to: |
Compare to
the similar Friedelite
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Varieties: |
None
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Synonyms: |
Bementite
(of Koenig)
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Crystal
Data
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Crystallography:
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Monoclinic
- Prismatic
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Crystal
Habit:
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Radiated
or stellate with minute foliated structure; compact,
hornlike forms; massive granular; in intricate intergrowths
with other minerals.
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Twinning:
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None
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Physical
Properties
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Cleavage: |
Perfect
on {001}, very Good on {100} and {010}
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Fracture: |
Conchoidal
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Tenacity:
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Flexible
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Moh's
Hardness: |
6.0;
Sometimes given as variable 4-6, softer mineral due to alteration.
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Density:
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2.90
- 3.10 (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: |
Brown, dark Drown, Golden Brown, Grayish-Yellow
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Transparency: |
Translucent
to Sub-Translucent
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Luster: |
Sub-Vitreous,
Resinous, Greasy, Pearly on perfect cleavage
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Refractive
Index: |
1.602
- 1.650 Biaxial ( - )
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Birefringence: |
0.026
- 0.030
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Dispersion: |
Weak
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Pleochroism: |
Weak;
colorless, pale yellow |
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Occurances
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Geological
Setting: |
Layered
parallel to the walls of secondary veins of calcite
in a metamorphosed stratiform zinc orebody (Franklin,
New Jersey, USA); intimately intergrown with other manganese
minerals (Olympic Peninsula, Washington, USA). |
Common
Associations: |
Calcite,
Willemite (Franklin, New Jersey, USA); Alleghanyite,
Barite, Braunite, Calcite, Grossular, Hausmannite, Jacobsite,
Johannsenite, (Olympic Peninsula, Washington, USA);
Hausmannite, Inesite, Rhodochrosite (Hale Creek, California,
USA). |
Common
Impurities: |
Al,
Fe, Zn, Mg, Ca |
Type
Locality: |
Trotter Mine (Lehigh Mine), Franklin, Franklin Mining District, Sussex Co., New Jersey, USA
|
Year
Discovered: |
1887
(IMA approved 1963) |
View
mineral photos: |
Bementite
Mineral Photos and Locations |
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More
Information
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|
Mindat.org
Webmineral.com
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Bementite
is a rare Manganese Silicate mineral that is found as
radiated or stellate crystals to massive granular forms
and often found in intricate intergrowths with other
minerals.
Bementite
localities are in the USA, at Franklin, Sussex County,
New Jersey; in Washington, on the Olympic Peninsula,
an ore mineral at a number of small deposits in Clallan,
Jefferson, and Mason Counties; from Ray, Pinal County,
Arizona; at Hale Creek, Trinity County, California;
and from the Black Diablo mine, Black Diablo district,
Pershing County, Nevada. In the Treburland mine, Altarnun,
Cornwall, and near Chillaten, Devon, England. From Langbån,
Värmland, Sweden. In Russia, at a number of poorly-defined
localities. In the Tokuzawa mine, Fukushima Prefecture;
the Ichinomata mine, Kumamoto Prefecture; and at Kunimiyama,
Kochi Prefecture, Japan. In the Wessels mine, near Kuruman,
Cape Province, South Africa.
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