To polish diamonds they make use of the powder of adamantine spar, or the corundum stone.
Pliny says, corundum was used in the form of a splinter fixed in an iron style.
The stones have been rubbed into shape apparently by corundum.
The color of corundum is usually brown, but it varies greatly.
There are indications of sapphires and other forms of corundum.
Corundum is the hardest substance known, next to the diamond.
The proportion of corundum in this emery is said to vary from 37 to 57%.
The corundum burr in McTeague's engine hummed in a prolonged monotone.
Well, the sapphire in all its beautiful tints is only a variety of corundum, colored by metallic oxide.
Quartz ought to exist in a state of hydrate, and Wavellite, not Corundum, ought to be the state of alumina in granite.
