Other important abrasives are emery and corundum, garnet, pumice,
diamond dust and bort, and feldspar.

Imports of abrasive materials into the United States have about
one-third of the value of those locally produced. While all of the
various abrasives are represented in these imports, the United States is
dependent on foreign sources for important parts of its needs only of
emery and corundum, garnet, pumice, diamond dust and bort, and grinding
pebbles.

Emery and corundum are used in various forms for the grinding and
polishing of hard materials--steel, glass, stone, etc. The principal
foreign sources of emery have been Turkey (Smyrna) and Greece (Naxos)
where reserves are large and production cheap. Production of corundum
has come from Canada, South Africa, Madagascar, and India. The domestic
production of emery is mainly from New York and Virginia, and corundum
comes from North Carolina. Domestic supplies are insufficient to meet
requirements, and cannot be substituted for the foreign material for the
polishing of fine glass and other special purposes. Curtailment of
imports during the war greatly stimulated the development of artificial
abrasives and their substitution for emery and corundum.

Garnet is used chiefly in the form of garnet paper for working leather,
wood, and brass. Garnet is produced mainly in the United States and
Spain. The United States is the only country using large amounts of this
mineral and imports most of the Spanish output. The domestic supply
comes mainly from New York, New Hampshire, and North Carolina.

Pumice is used in fine finishing and polishing of varnished and enameled
surfaces, and in cleaning powders. The world's principal source for
pumice is the Lipari Islands, Italy. There is a large domestic supply of
somewhat lower-grade material (volcanic ash) in the Great Plains region,
and there are high-grade materials in California and Arizona. Under war
conditions these supplies were drawn on, but normally the high-quality
Italian pumice can be placed in American markets more cheaply.

Diamond dust is used for cutting gem stones and other very hard
materials, and borts or carbonadoes (black diamonds) for
diamond-drilling in exploration. Most of the black diamonds come from
Brazil, and diamond dust comes from South Africa, Brazil, Borneo, and
India.

Chert or flint pebbles for tube-mills are supplied mainly from the
extensive deposits on the French and Danish coasts. The domestic