{ Neph"e*line (?), Neph"e*lite (?) }, n. [gr. &?; cloud: cf. F. néphéline. Cf. Nebula.] (Min.) 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.

• A feldspathoid mineral of silica-poor igneous, plutonic and volcanic rocks. Chemically, Nepheline is a plagioclase feldspar with insufficient silica to satisfy the chemical bonds. Because of the unfilled bonds, Nepheline weathers rapidly and can only be seen as inclusions in freshly broken rock.