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albite

Albite is a mineral in the feldspar group, with the chemical formula NaAlSi3O8. It represents the sodium endmember of the plagioclase solid solution series, the calcium endmember being anorthite (CaAl2Si2O8). Albite crystallizes in the triclinic system and commonly occurs as colorless to white crystals or pale gray to pinkish masses. It has a vitreous luster, a Mohs hardness of 6–6.5, and a specific gravity around 2.62–2.66. Like other plagioclase feldspars, it exhibits two good cleavages at or near 90 degrees and often shows characteristic twinning.

Occurrence and formation: Albite is widely found in felsic igneous rocks such as granites, granodiorites, and

Name and use: The name albite derives from Latin albus, meaning white, in reference to its typical

rhyolites,
and
can
also
occur
in
low-grade
metamorphic
rocks.
In
rocks,
it
commonly
coexists
with
quartz
and
other
feldspars,
and
its
proportion
relative
to
calcium
endmembers
helps
define
the
rock’s
plagioclase
composition.
The
distribution
of
albite
within
a
rock
reflects
its
crystallization
history
and
the
overall
chemical
composition
of
the
magma
or
metamorphic
grade.
color.
As
a
major
feldspar
mineral,
albite
is
mined
as
a
source
of
sodium
feldspar
for
glassmaking
and
ceramics,
and
it
serves
as
a
useful
diagnostic
mineral
in
geological
studies
for
identifying
igneous
and
metamorphic
rocks
and
assessing
plagioclase
composition
in
samples.