'Castorite' definitions:

Definition of 'Castorite'

From: GCIDE

Castor \Cas"tor\, Castorite \Cas"tor*ite\, n. [The minerals castor and pollux were so named because found together on the island of Elba. See Castor and Pollux.] (Min.) A variety of the mineral called petalite, from Elba. [1913 Webster]