Corundums [noun]

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.

This is true whether it has reference to a grindstone, emery, corundum wheel, or a plain oil stone.

Corundum and pure emery are ores that are very rich in aluminum, containing about fifty-four per cent.

Corundum is the hardest substance known, next to the diamond.

Corundum is characterised by a high specific gravity (4.0) and extreme hardness.

In composition it differs entirely from sapphire, or the rhombohedral corundum.

Spinelle Ruby, called Dodecahedral corundum by some mineralogists, and Balas ruby by lapidaries.

Its name was derived from carbon and corundum (a form of alumina), from a mistaken view as to its composition.

Copper ore is found in many tracts throughout India, plumbago in Madras, and corundum in southern India.