A colourless, greenish, or brownish mineral consisting of an aluminosilicate of sodium (often with potassium) and occurring as crystals and grains in igneous rocks.‘All basalt chemical compositions can be plotted in the basalt tetrahedron, which has normative quartz, olivine, nepheline and augite at the apices.’
- ‘The three commonest feldspathoids are leucite, nepheline, and sodalite.’
- ‘The other is a small lazurite deposit at the southern end of Baffin Island, Nunavut, Canada, where it is found as rounded, isolated grains in nepheline and is associated with diopside.’
- ‘The groundmass of these leucocratic segregations is heterogeneous, consisting of centimeter-scale regions dominated by nepheline, natrolite, alkali feldspar, or wollastonite.’
- ‘Additionally, lamproites may contain leucite, richterite, sanidine, and occasionally nepheline, whereas kimberlites do not.’
Early 19th century from French néphéline, from Greek nephelē ‘cloud’ (because its fragments are made cloudy on immersion in nitric acid) + -ine.