Talc

a common, non-metallic mineral. It is composed chiefly of magnesia, silica, and water. It is allied to mica. Like mica, it occurs in sheets readily separated into thin plates, and also in masses. Talc has a greasy, soapy feeling. Its color varies from a silvery white to apple green. In Moore's scale of hardness as applied to minerals, a scale of ten, talc is called type one, the diamond at the other extreme, type ten. Talc is cut readily, but it is surprisingly tough. Certain forms of talc are known as steatite or soapstone. A whitish variety is known as French chalk.

There are enormous beds of talc in the United States. The chief sources of supply are North Carolina, Virginia, and St. Lawrence County, New York. The American product for 1903 is estimated by the United States geological survey at 26,671 tons, valued at $418,460. Talc has many uses in the arts. It is acid-proof, and withstands a high degree of heat. Flour talc is extensively employed in fireproofing. It is used to absorb nitroglycerin in the manufacture of dynamite. Talc has value also in the manufacture of soaps, in dressing leather, and in making axle grease. It is an ingredient in the manufacture of paper; talc sizing increases the weight, and gives smoothness and additional strength. Soapstone, that is to say talc, griddles may be used without grease. The Chinese and Japanese carve many ornaments, miniature idols, etc., out of talc. Talcum powder is a well known article of the toilet. Steatite, sawed into slate pencils and blackboard crayons of a greenish color, is used in many schools. The tailor's crayon with which he marks his cloth before cutting is made of steatite.

Soapstone is about the only stone that may be heated hot and sprinkled with water or even plunged into water without cracking. The North American Indians were aware of this peculiar quality. The Eskimos made soapstone lamps in which, by means of moss wicks, they burned blubber for light and heat. Soapstone lamps, griddles, kettles, and pans are still found in Indian villages up and down the Pacific coast. The Indian women of southern California were skillful in making a pot called by the Spanish priests an olla. It was a foot or more in diameter and was almost spherical in form. It was scraped smooth inside and out with a piece of flint or bone. The mouth was barely large enough to admit the hand. Utensils made of this potstone material appear to have been the forerunners of the native pottery for which the Indians of the Southwest are noted.

See Pottery