The earth alumina, as found native in a crystalline state, including sapphire, which is the fine blue variety; the oriental ruby, or red sapphire; the oriental amethyst, or purple sapphire; and adamantine spar, the hair-brown variety. It is the hardest substance found native, next to the diamond.
Corundum, also known as aluminum oxide, is not magnetic. It is a diamagnetic material, meaning it does not have any magnetic properties and is very weakly repelled by magnetic fields.
Corundum has a basal cleavage, meaning it cleaves parallel to its basal plane. This cleavage is often poor and can be difficult to observe.
Corundum.
Corundum ( (Al_2O_3) ) is hexagonal in crystal structure.
Corundum is in the trigonal crystal system.
Corundum is used for jewlery
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.
Corundum is aluminium oxide, Al2O3.
Sapphire is a gemstone variety of the mineral corundum, an aluminium oxide. Trace amounts of other elements such as iron, titanium, chromium, copper, or magnesium can give corundum blue, yellow, purple, orange, or a greenish color.
Red corundum is called ruby.
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.