Corundum is found in a large number of localities in North Carolina. The most important occurrences of corundum are in or near peridotite masses, also in schists, and in alluvial deposits. Active mining work was first begun in 1871 and continued until about 1906, when North Carolina corundum was driven from the market by the competition of Canadian corundum and artificial abrasives. Corundum mining was revived in 1915, and the three properties worked in 1917 made an output of 820 tons. There is unquestionably a very large reserve of corundum in this region, but transportation is difficult and efficient labor is scarce; so that there is little immediate prospect of a large development.
The only commercially important deposits of abrasive corundum west of the Appalachian Mountains are in the central part of Gallatin County near Salesville, Montana, where corundum occurs in syenite and syenite pegmatite. The deposits have been worked by three companies, and up to 1903, when operations ceased, had produced several hundred tons of corundum.
The sources in Canada of abrasive corundum of commercial importance are limited to the corundum syenites and anorthosites in central Ontario. These deposits have been developed and mined only at the Burgess mines and at Craigmont. Corundum mining as an industry in Canada began in 1900. The production reached a maximum in 1906 and was smaller and fairly uniform from 1907 to 1913, in which year operations were practically suspended.
The reported occurrences of corundum in Mexico and Central and South America are chiefly of the gem variety. Emery is reported from Musco, Colombia, and common corundum is reported as especially abundant at localities in the State of Sao Paulo, Brazil.
The only occurrence of emery and corundum of commercial importance in Europe is in the islands of the Grecian Archipelago, particularly the Island of Naxos. The deposits occur there as lenses and masses in limestones and in the vicinity of granites. Exploration and development work has been superficial, but reserves or future supplies there are probably enormous. Annual exports during the years 1897 to 1914 averaged 6,800 metric tons.
In Asia there are commercial corundum deposits in Asiatic Turkey and in India.
The emery deposits of Asiatic Turkey are near Smyrna. The Turkish emery is similar in origin and general character to the Greek emery, except that none is found in Asia Minor of quite the superior quality of that of Naxos. The main source of supply seems so far to have been from the detrital deposits. It seems almost certain that supplies are large. The emery mines of Asia Minor are very old and have annually contributed large quantities to the world’s supply, their output having been larger than from any other region in the world. Statistics for recent years are lacking. The recorded output in official reports of the Turkish government was about 62,000 metric tons in 1908 and about 25,000 in 1909.
The corundum deposits of India are numerous and include not only the common abrasive varieties but also the most highly prized gem varieties. Commercially important deposits of the abrasive variety occur in the presidency of Madras. The following provinces and native states also contain the mineral in more or less abundance: Afghanistan, Bengal, Burma, Central Provinces, Punjab, and Travancore.
Available data on the production of corundum in India indicate an output between 100 and 500 long tons a year, up to and including 1915. In 1916 the production was approximately 2,000 long tons and since then it has probably equaled or exceeded that figure. Nothing definite is known as to the corundum resources of India, except that they are undoubtedly large.
The only recorded deposits of abrasive corundum in commercial quantities on the continent of Africa are in the vicinity of Pretoria, in the Transvaal, where corundum, probably occurring originally in schists, is concentrated from residual material on the land surface. Little information concerning these corundum deposits is available, but it is probable that large reserves may be developed. The production, which had been slight or negligible prior to 1912, expanded greatly in 1917 to about 3,000 long tons.