tuch’stone.

A stone by which metals are examined; a black, smooth, glossy stone. The touchstone of the ancients was called lapis Lydius, from Lydia in Asia Minor, where it was found.

Any test or criterion by which the qualities of a thing are tried; as money, the touchstone of I§common honesty. Irish touchstone, is the basalt, the stone which composes the Giants causey. This is said also to be an excellent touchstone.