Corundum
a rhombohedral transparent or translucent mineral, very tough when compact. Its hardness is 9, its sp. gr. 3.9-4.16. Its luster is generally erally vitreous; vitreous; its colors blue, red, yellow, brown, gray, or nearly white; its streak in all cases colorless. It consists of pure alumina. Chemically viewed, it is aluminum-oxide, Al₂Os. There are three varieties of it-sapphire, corundum proper, and emery. It includes the species of the genus which are dark in color and only translucent; but its hues may be light blue, gray, brown, or black.
The United States imports corundum to the value of $100,000 every year, principally from Canada. CORUNNA (Spanish Coruña), a seaport of Spain, in the province of the the bay of Betanzos. It consists of an upper and a lower town, the former built on the E. side of a small peninsula, and the latter on the isthmus connecting the peninsula with the mainland. The harbor, which is well protected, is deep, spacious and safe. Cattle form the chief export. There is a government tobacco factory employing thousands of women and girls. There is a lighthouse, 92 feet high, called the Tower of Hercules, and supposed to be of Roman construction. Corunna was the port of departure of the Spanish Armada (1588), and the scene of the repulse of the French and the death of Sir John Moore (1809). Pop. about 60,000.
CORVÉE, an obligation on the tenants form certain services for their lord, such or of certain districts to per-