DIALLAGE, noun [Gr., difference, alluding to the difference of luster between its natural joints.] A mineral, the smaragdite of Saussure, of a lamellar or foliated structure. Its subspecies are green diallage metalloidal diallage and bronzite. The metalloidal subspecies is called schillersteing, or shiller spar.
Source: Webster's 1828 American Dictionary ↗ · public-domain · returned verbatim, no AI