[mass noun] A colourless, greenish, or brownish mineral consisting of an aluminosilicate of sodium (often with potassium) and occurring as crystals and grains in igneous rocks.
- ‘The groundmass of these leucocratic segregations is heterogeneous, consisting of centimeter-scale regions dominated by nepheline, natrolite, alkali feldspar, or wollastonite.’
- ‘All basalt chemical compositions can be plotted in the basalt tetrahedron, which has normative quartz, olivine, nepheline and augite at the apices.’
- ‘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 three commonest feldspathoids are leucite, nepheline, and sodalite.’
- ‘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.