nephelite,
n. [Gr.
nefe`lh cloud: cf. F.
néphéline. Cf.
Nebula.].
A mineral occuring at Vesuvius, in glassy hexagonal crystals; also elsewhere, in grayish or greenish masses having a greasy luster, as the variety elæolite. It is a silicate of aluminia, soda, and potash. [1913 Webster]