Corundum is a very hard mineral used as an abrasive in industry.
Corundum.
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Corundum ( (Al_2O_3) ) is hexagonal in crystal structure.
Corundum is in the trigonal crystal system.
Corundum is used for jewlery
Red corundum is called ruby.
Corundum is aluminium oxide, Al2O3.
Une facture.
Diamond is the hardest mineral and is the only one that can scratch corundum. but in my opinion corundum will scratch corundum any mineral of the same hardness will scratch the other !
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Red corundum is called ruby.