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calciet

Calciet, or calcite in English, is a widespread carbonate mineral with the chemical formula CaCO3. It is the most stable polymorph of calcium carbonate at Earth's surface conditions and is a principal component of sedimentary rocks such as limestone and metamorphic rocks such as marble. Calciet occurs in a variety of crystal habits and can form large, well-shaped crystals or massive, granular aggregates.

Calciet crystallizes in the trigonal crystal system and most commonly forms rhombohedral crystals. It has perfect

Formation and occurrence: Calciet forms through chemical and biological precipitation in marine and freshwater environments and

Uses: The mineral is a major source of lime and cement and is used as an aggregate

See also: Aragonite, Limestone, Dolomite, Marble, Cement.

cleavage
in
three
directions
and
a
Mohs
hardness
of
3.
The
mineral
is
usually
colorless
or
white,
but
impurities
can
impart
a
wide
range
of
colors,
including
yellows,
reds,
greens,
and
browns.
It
displays
a
vitreous
to
sugary
luster
and,
in
transparent
varieties,
exhibits
characteristic
double
refraction
and
birefringence.
Calciet
is
relatively
dense,
with
a
typical
specific
gravity
around
2.71
g/cm3.
A
well-known
transparent
variety
is
Iceland
spar,
valued
for
its
optical
properties
in
polarized
light
experiments.
as
a
primary
constituent
of
limestone
and
marble
formed
by
diagenesis
and
metamorphism.
It
is
abundant
in
sedimentary
basins,
and
also
occurs
in
hydrothermal
veins
and
caverns,
where
speleothems
such
as
stalactites
and
stalagmites
can
be
composed
largely
of
calciet.
and
filler
in
construction
materials,
plastics,
and
paper.
It
also
serves
as
a
decorative
stone
and
is
used
in
some
optical
and
polishing
applications,
and
as
a
standard
reference
in
petrographic
microscopy.