Name | CORUNDUM | Variety | SAPPHIRE | Origin | Ratnapura (Sri Lanka) | Hardness | 9 | Composition | Al2O3 | Crystaline sys. | TRIGONAL
| Size | 6,5 x 3 cm | Weight | 54,5 gr |
Description:
Corundum was chosen by the geologist Friedrich Mohs to represent grade 9 in his famous scale first published in 1825 and which is still valid today. It is second hardest material on Earth. Corundum crystals usually appear alone. True crystal twins (except for synthetic ones) are extremely rare, as are groupings of crystals. This specimen not only shows a polysynthetic twinning, but is also formed by various interpenetrated crystals. |
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CORUNDUM
VARIETY SAPPHIRE
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