Definition of feldspathoid in English:

feldspathoid

noun

Geology
  • Any of a group of minerals chemically similar to feldspar but containing less silica, such as nepheline and leucite.

    • ‘The change from incompatible to compatible behavior heralds the onset of significant plagioclase (or feldspathoid) precipitation/removal.’
    • ‘Afghanite occurs as small, typically colorless transparent crystals associated with a wide variety of feldspathoids in volcanic ejecta collected in the general Mount Vesuvius area, Italy.’
    • ‘The three commonest feldspathoids are leucite, nepheline, and sodalite.’

Pronunciation:

feldspathoid

/ˈfɛl(d)spəˌθɔɪd/