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Mg3Al2Si3O12

Mg3Al2Si3O12 is the chemical formula for pyrope, a magnesium aluminum silicate that is a end-member of the garnet group. In the general garnet structure, the formula is X3Y2(SiO4)3, with X and Y occupying distinct lattice sites; for pyrope, X is Mg2+ and Y is Al3+. This composition gives rise to the characteristic cubic garnet structure.

Pyrope forms in high-temperature, high-pressure metamorphic rocks such as granulites and eclogites, as well as in

In terms of properties, pyrope crystallizes in the isometric (cubic) crystal system and typically forms euhedral,

As a gemstone, pyrope garnet is valued for its red hues and clarity, though gem-quality material is

ultramafic
igneous
rocks
derived
from
the
mantle.
It
is
a
common
constituent
of
mantle
xenoliths
carried
to
the
surface
by
kimberlites
and
is
often
found
with
other
garnet
end-members
like
almandine
and
grossular.
The
mineral
is
widely
used
by
geologists
as
a
geothermobarometric
indicator
due
to
its
stable
Fe–Mg
exchange
with
other
garnet-bearing
minerals
under
metamorphic
conditions.
dodecahedral
crystals.
Its
color
ranges
from
pinkish
to
deep
red,
and
it
is
generally
hard
(about
7
to
7.5
on
the
Mohs
scale).
Garnets
are
isotropic,
showing
no
pleochroism,
and
have
a
specific
gravity
roughly
in
the
range
of
3.57
to
3.98,
depending
on
trace
elements.
less
common
than
some
other
garnets.
It
is
marketed
simply
as
pyrope
garnet,
and
mixtures
with
other
garnet
components
(such
as
in
rhodolite)
can
influence
color
and
price.