society > occupation and work > materials > raw material > mineral material > [noun] > basanite (3)
a black variety of jasper (basanite) used by jewellers as a touchstone for testing gold.
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…
= Lydian-stone n. at Lydian, adj. 3.