The value of the mineral corundum will vary according to its appearance. Gem quality corundum is highly valued. Non gem quality corundum has many industrial uses and is much less highly valued.
Corundum.
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.
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 !
Red corundum is called ruby.
100% of rubies are corundum. "Ruby" is a name made up by the gem trade for the mineral known as corundum, when it is red.
According to the Mohs scale of mineral hardness, quartz (7) will not scratch any mineral with a higher number on the scale. Corundum is listed at 9. Therefore quartz will not scratch corundum, but corundum can scratch quartz.
Corundum is a mineral, therefore it could not be the hardest rock.
Corundum is used as an abrasive powder to polish lenses.