Potassium Calcium Silicate Aluminate
[Na9-1,Ca0-4(Si27Al9)O72]*28(H2O)
![Potassium Calcium Silicate Aluminate - [Na9-1,Ca0-4(Si27Al9)O72]*28(H2O)](../bilder/kristalle/stilbite-3473.jpg "Potassium Calcium Silicate Aluminate - [Na9-1,Ca0-4(Si27Al9)O72]*28(H2O)")
![Potassium Calcium Silicate Aluminate - [Na9-1,Ca0-4(Si27Al9)O72]*28(H2O)](../bilder/kristalle/stilbite-3482.jpg "Potassium Calcium Silicate Aluminate - [Na9-1,Ca0-4(Si27Al9)O72]*28(H2O)")
![Potassium Calcium Silicate Aluminate - [Na9-1,Ca0-4(Si27Al9)O72]*28(H2O)](../bilder/kristalle/stilbite-3494.jpg "Potassium Calcium Silicate Aluminate - [Na9-1,Ca0-4(Si27Al9)O72]*28(H2O)")
![Potassium Calcium Silicate Aluminate - [Na9-1,Ca0-4(Si27Al9)O72]*28(H2O)](../bilder/kristalle/stilbite-3505.jpg "Potassium Calcium Silicate Aluminate - [Na9-1,Ca0-4(Si27Al9)O72]*28(H2O)")
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Chemical name
Potassium Calcium Silicate Aluminate |
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Mineral name
Stilbite |
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Chemical formula
[Na9-1,Ca0-4(Si27Al9)O72]*28(H2O) |
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Crystal system
monoclinic |
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Crystal Class
monoclinic-prismatic (2/m) |
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Space Group
C2/m |
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Unit cell
a [Å]:13.63 b [Å]:18.17 c [Å]:11.31 |
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Formula units
Z=4 |
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Twinning
common on {001} (penetration twinning) |
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Mohs hardness
3.5 - 4 |
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Density [g/cm3]
2.1 - 2.2 |
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Cleavage
perfect on {010} |
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Fracture / Tenacity
uneven to conchoidal |
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Color
colorless (usually), white, pink |
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Streak
white |
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Transparency
transparent to translucent |
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Luster
vitreous, pearly on cleavage surfaces |
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Optical character
biaxial (-) |
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Refractive Index
nα=1.484-1.500; nβ=1.492-1.507; nΥ=1.494-1.513 |
