nepheline
noun
neph·e·line ˈne-fə-ˌlēn 
variants or less commonly nephelite
ˈne-fə-ˌlīt
: a hexagonal mineral that is a usually glassy crystalline silicate of sodium, potassium, and aluminum common in igneous rocks
nephelinic
ˌne-fə-ˈli-nik
adjective 
Word History
Etymology
French néphéline, from Greek nephelē cloud — more at nebula
First Known Use
circa 1814, in the meaning defined above