Name CORUNDUM
Variety CORUNDUM (TWIN)
Origin Ratnapura (Sri Lanka)
Hardness 9
Composition Al2O3
Crystaline sys. TRIGONAL
Size   3,9x3,3x1,5 cm
Weight 21,3 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. Real crystal twins, like this, are extremely rare except the polisynthetic tipe.


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CORUNDUM



VARIETY CORUNDUM (TWIN)