nepheline definition by Wordo

Noun

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

.