ගිනිබොකු තෝර |
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Andalusite |
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Category | Nesosilicates |
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රසායනික සූත්රය | Al2SiO5 |
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Strunz classification | 09.AF.10 |
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Crystal symmetry | 2/m 2/m 2/m - Dipyramidal |
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Unit cell | a = 7.7980 Å b = 7.9031 Å c = 5.5566 Å; Z = 4 |
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පාට / පැහැය | Pink, violet, yellow, green, white, gray; in thin section, colorless to pink or green |
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Crystal habit | As euhedral crystals or columnar aggregates having nearly square cross sections; fibrous compact to massive |
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Crystal system | orthorhombic |
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Twinning | On {101}, rare |
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Cleavage | Good on {110}, poor on {100} |
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Fracture | uneven to subconchoidal |
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Mohs scale hardness | 6.5 - 7.5 |
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Luster | Vitreous |
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Streak | White |
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Diaphaneity | Transparent to nearly opaque with inclusions |
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Specific gravity | 3.17 (+/- .04) |
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Optical properties | double refractive, biaxial negative; chiastolite has anomalous aggregate reaction.[1] |
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Refractive index | nα = 1.629 - 1.640 nβ = 1.633 - 1.644 nγ = 1.638 - 1.650 |
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Birefringence | δ = 0.009 - 0.010 |
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Pleochroism | Weak |
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2V angle | 71 - 86° |
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Dispersion | r < v strong |
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Ultraviolet fluorescence | non-fluorescent |
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References | [1][2][3][4] |
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