Sepiolite
| Sepiolite | |
|---|---|
A sample of sepiolite
|
|
| General | |
| Category | Phyllosilicates |
|
Formula (repeating unit) |
Mg4Si6O15(OH)2·6H2O |
| Strunz classification | 9.EE.25 |
| Dana classification | 74.03.01b.01 Palygorskite-sepiolite group |
| Crystal system | Orthorhombic |
| Crystal class | Dipyramidal (mmm) H-M symbol: (2/m 2/m 2/m) |
| Space group | Pnna |
| Unit cell | a = 5.21 Å, b = 26.73 Å c = 13.5 Å; Z = 4 |
| Identification | |
| Color | Grayish white, white, white with a yellowish or reddish tinge; bluish green |
| Crystal habit | Compact nodular, earthy, clayey, massive; rarely fine fibrous along [001] |
| Mohs scale hardness | 2 |
| Luster | Dull, earthy |
| Streak | White |
| Diaphaneity | Opaque |
| Specific gravity | 2; dry porous masses float on water |
| Optical properties | Biaxial (-) |
| Refractive index | nα = 1.520 nβ = 1.520 nγ = 1.530 |
| Birefringence | δ = 0.010 |
| 2V angle | Measured: 20° to 70°, Calculated: 18° |
| References | |
Sepiolite, also known as meerschaum (
i/ˈmɪərʃɔːm/ MEER-shawm or /ˈmɪərʃəm/ MEER-shəm, German for foam of the sea) is a soft white clay mineral, often used to make tobacco pipes (known as meerschaum pipes). A complex magnesium silicate, a typical chemical formula for which is Mg4Si6O15(OH)2·6H2O, it can be present in fibrous, fine-particulate, and solid forms.
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