ˈkastəˌrīt, -ˈaa-, -ˈai-, -ˈȧ- noun
or cas·tor -tə(r)
( -s )
Etymology: castorite from German kastor (from Kastor mythological personage, from Latin Castor ) + English -ite; castor from German kastor; from its appearance with pollucite (previously called pollux )
: a mineral consisting of a variety of petalite occurring in transparent crystal