Sepiolite
| Sepiolite | |
|---|---|
|
A sample of sepiolite | |
| General | |
| Category | Phyllosilicates |
| Formula (repeating unit) | Mg4Si6O15(OH)2·6H2O |
| Strunz classification | 09.EE.25 Single tetrahedral nets of 6-membered rings |
| Dana classification | 74.03.01b.01 Palygorskite-sepiolite group |
| Crystal symmetry | Orthorhombic 2/m2/m2/m |
| 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] |
| Crystal system | Orthorhombic - Dipyramidal |
| 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 | [1][2][3] |
Sepiolite is a clay mineral, a complex magnesium silicate, a typical formula for which is Mg4Si6O15(OH)2·6H2O. It can be present in fibrous, fine-particulate, and solid forms.
It was first described in 1847 for an occurrence in Bettolino, Baldissero Canavese, Torino Province, Piedmont, Italy. The name comes from a perceived resemblance of the material to the porous bones of the cuttlefish from the Greek, "sepion".[2] Because of its low specific gravity and its high porosity it may float upon water, hence its German name meerschaum ("sea foam").
Sepiolite occurs as a secondary mineral associated with serpentine. It can occur as a precipitate in arid environments. It may be associated with dolomite and opal.[1][3]
Owing to its fibrous mineral nature, sepiolite veins may contain the hazardous material, asbestos; even where asbestos is not present, sepiolite is often mistaken for it. Careful analytical techniques may be required to distinguish the two.
Applications
Sepiolite is used in oil drilling, for cat litter and in a solid form for carving of items, where it is known as Meerschaum. In construction, sepiolite can be used in lime mortars as water reservoir.[4][5]
References
- ↑ 1.0 1.1 Handbook of Mineralogy
- ↑ 2.0 2.1 Mindat.org
- ↑ 3.0 3.1 Webmineral data
- ↑ ANDREJKOVIČOVÁ et al., (2011) Fine sepiolite addition to air lime-metakaolin mortars. Clay Minerals, 46 (4): 624-635. DOI: 10.1180/claymin.2011.046.4.621
- ↑ ANDREJKOVIČOVÁ et al., (2012) Air lime mortars with incorporation of sepiolite and synthetic zeolite pellets. Acta Geodynamica et Geomaterialia, 9 (1): 79-91
 |
Wikimedia Commons has media related to Sepiolite. |
| ||||||||||||||||||||||