Sep 26 2013
Topics Covered
Introduction to Asisite
Properties of Asisite
How to Identify Asisite
Global Distribution
Occurrence of Asisite and Useful Mineral Association
References
Introduction to Asisite
Chemical Formula - Pb7SiO8Cl2
Asisite was named after the Asis farm located at the Kombat mine, Namibia.
Properties of Asisite
The following are the key properties of asisite:
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Cell Data
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Space group: I 4/ mmm
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a = 3.897(2)
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c = 22.81(2)
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Z = 1
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Crystal Data
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Tetragonal
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Point group: 4/m 2/m 2/m
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Platy, to about 0.5 mm
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X-ray powder pattern: 2.957 (100), 2.752 (60), 1.627 (60), 1.602 (50), 3.46 (40), 1.984 (40), 1.747 (40)
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Chemical Composition
|
Elements |
Content 1 |
|
PbO |
93.7 |
|
Cl |
4.4 |
|
SiO2 |
2.0 |
|
-O = Cl2 |
1.0 |
|
Total |
99.1 |
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Optical Properties
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Optical class: Uniaxial (-)
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ω = 2.39
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ε = 2.32
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Anisotropism: Weak in oil, gray; not noticeable in air
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R1-R2: (400) 20.6-20.7, (420) 19.8-19.8, (440) 19.0-19.15, (460) 18.5-18.65, (480) 18.1-18.2, (500) 17.7-17.9, (520) 17.4-17.55, (540) 17.15-17.3, (560) 16.9-17.0, (580) 16.7-16.8, (600) 16.6-16.7, (620) 16.5-16.5, (640) 16.3-16.4, (660) 16.2-16.3, (680) 16.1-16.2, (700) 16.0-16.1
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Estimated Properties
|
Electron density |
Bulk density (electron density) = 6.47 g/cm3
note: Specific gravity of asisite = 7.94 g/cm3 |
|
Photoelectric |
PEAsisite = 1,653.44 barns/electron
U=PEAsisite x ρ electron density= 10701.44 barns/cm3 |
|
Fermion index |
Fermion index = 0.19
Boson index = 0.81 |
|
Radioactivity |
Asisite is not radioactive |
How to Identify Asisite
Asisite can be identified in the field by its green-yellow and yellow color variations. Its transparent form has {001} perfect cleavage.
This mineral has an adamantine luster with yellow white streak. The hardness of asisite is 3.5- approximate to a copper penny.
Global Distribution
Asisite is distributed mainly in Namibia in the Kombat mine, 49 km south of Tsumeb.
Occurrence of Asisite and Useful Mineral Association
Asisite occurs in manganese silicate lenses nearby a sulfide ore body. It is often associated with minerals such hematophanite, chlorite, barite, hematite, molybdophyllite, jacobsite, and copper,
References