Adular
(K,Na)(S7iAl)4O8
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Chemical name
Adular |
|
Chemical formula
(K,Na)(S7iAl)4O8 |
|
Crystal system
monoklin |
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Crystal Class
Prismatic (2/m) |
|
Space Group
C2/m |
|
Unit cell
a [Å]:8.56 b [Å]:12.96 c [Å]:7.21 |
|
Formula units
Z=4 |
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Mohs hardness
6 - 6.5 |
|
Density [g/cm3]
2.55 - 2.63 |
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Cleavage
(001) perfect, (010) good |
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Luster
Vitreous, pearly on cleavage surfaces |
|
Refractive Index
nα = 1.518-1.520, nβ = 1.522-1.524, nγ = 1.522-1.525 |
|
Birefringence δ
0.004 - 0.005 |
