Bentorite
Bentorite is a mineral with the chemical formula Ca6(Cr,Al)2(SO4)3(OH)12·26H2O. It is colored violet to light violet. Its crystals are hexagonal to dihexagonal dipyramidal. It is transparent and has vitreous luster. It has perfect cleavage. It is not radioactive. Bentorite is rated 2 on the Mohs scale.
| Bentorite | |
|---|---|
Bentorite found in Israel | |
| General | |
| Category | Mineral |
| Formula (repeating unit) | Ca6(Cr,Al)2(SO4)3(OH)12· 26H2O |
| IMA symbol | Bto |
| Strunz classification | 7.DG.15 (9th Ed) |
| Dana classification | 31.10.2.2 |
| Unit cell | 2,355.60 ų |
| Identification | |
| Colour | Violet to rose-purple |
| Twinning | (1010) |
| Cleavage | Perfect |
| Fracture | Sub-conchoidal |
| Mohs scale hardness | 2 |
| Luster | Resinous, waxy, earthy |
| Streak | Very pale purple |
| Specific gravity | 2.025 |
| Density | 2.025 g/cm3 (measured) |
| Birefringence | 0.006 |
| Pleochroism | Visible |
| Extinction | Parallel |
| Ultraviolet fluorescence | Not fluorescent |
| Absorption spectra | E > O |
The mineral was first described in 1980 by Shulamit Gross for an occurrence in the Hatrurim Formation of Danian age along the western margin of the Dead Sea, Israel. It was named by its discoverer, Shulamit Gross, for Yaakov Ben-Tor (1910–2002), Professor at the Hebrew University of Jerusalem and the University of California, San Diego, California, US, for his contributions to geology and mineralogy in Israel.
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