What is the composition of nepheline?

What is the composition of nepheline?

Nepheline Mineral Data

Is nepheline a mineral or rock?

Nepheline, also called nephelite (from Ancient Greek νεφέλη (nephélē) ‘cloud’), is a rock-forming mineral in the feldspathoid group – a silica-undersaturated aluminosilicate, Na3KAl4Si4O16, that occurs in intrusive and volcanic rocks with low silica, and in their associated pegmatites.

Is nepheline a silicate?

Nepheline Syenite is an anhydrous sodium potassium alumino silicate. Although feldspar-like in its chemistry, mineralogically it is an igneous rock combination of nepheline, microcline, albite and minor minerals like mica, hornblende and magnetite.

What is the meaning of nepheline?

Definition of nepheline : a hexagonal mineral that is a usually glassy crystalline silicate of sodium, potassium, and aluminum common in igneous rocks.

Is nepheline mafic or felsic?

Nepheline syenite is characterized by high ratio of (Na2O+K2O)/SiO2 and (Na2O+K2O)/Al2O3, which are represented respectively by the existence of nepheline and alkaline mafic minerals. Therefore, it is classified geochemically as alkaline rock.

How can you identify a nepheline in a thin section?

Nepheline is colorless under plane polarized light in thin section. Click on the image to see the crystal under crossed polars. This hexagonal crystal is oriented with its optic axis vertical.

What type of rock is nepheline?

nepheline syenite, medium- to coarse-grained intrusive igneous rock, a member of the alkali-syenite group (see syenite) that consists largely of feldspar and nepheline. It is always considerably poorer in silica and richer in alkalies than granite.