nepheline

nepheline

English Noun

Definition

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.

Etymology

From Ancient Greek νεφέλη (nephélē, “cloud”), because crystals become cloudy when exposed to acid, + -ine.