Name CORUNDUM
Variety SAPPHYRE (SEVERAL)
Origin Ratnapura (Sri Lanka)
Hardness 9
Composition Al2O3
Crystaline sys. TRIGONAL
Size   VARIAS/SEVERAL
Weight VARIOS/SEVERAL




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. There are more than thirty corundum crystals in our collection. Here we show four of them of different colours.


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CORUNDUM



VARIETY SAPPHYRE (SEVERAL)