basanite Min.
(ˈbæsənaɪt)
[ad. L. basanītes (lapis), in Pliny, f. Gr. βάσανος touchstone, test.]
A velvet-black siliceous variety of quartz, used on account of its blackness and hardness for testing the purity of precious metals, by means of the mark left after rubbing the metal upon it.
| [1753 Chambers Cycl. Supp., Basanites..the touchstone used for trying gold.] 1794 Kirwan Min. I. 307 Basanite. Lydian stone of Werner. Black Jasper of some. 1850 Müller's Anc. Art §403 Statue of the Nile..of basanite. |