Touchstone

Description

A hard, black, fine-grain stone that is composed of flint, Lydian stone, or basanite. Touchstone are used for evaluating the purity of gold and silver. The gold or silver piece is rubbed against the touchstone, then the color of the streak is compared to reference streaks of known composition in order to determine the quality of the precious metal.

Synonyms and Related Terms

basanite

Authority

• Henry Hodges, Henry Hodges, Artifacts: An Introduction to Early Materials and Technology, Ronald P. Frye, Kingston, Canada, 1988

• Encyclopedia Britannica, http://www.britannica.com Comment: "Touchstone." Encyclopdia Britannica. 2004. Encyclopdia Britannica Premium Service. 9 May 2004 .

• Thomas Gregory, Thomas Gregory, The Condensed Chemical Dictionary, Reinhold Publishing, New York, 3rd ed., 1942

• G.S.Brady, G.S.Brady, Materials Handbook, McGraw-Hill Book Co., New York, 1971 Comment: p. 334

• Random House, Random House, Webster's Encyclopedic Unabridged Dictionary of the English Language, Grammercy Book, New York, 1997

• The American Heritage Dictionary or Encarta, via Microsoft Bookshelf 98, Microsoft Corp., 1998

• George Savage, George Savage, Art and Antique Restorer's Handbook, Rockliff Publishing Corp, London, 1954