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gypsos

Gypsos is the ancient Greek word for gypsum, the sulfate mineral commonly known in English as gypsum. In mineralogical terms, gypsum has the chemical formula CaSO4·2H2O, is soft with a Mohs hardness of about 2, and shows perfect cleavage in three directions. It is typically white or colorless, though impurities can impart gray, yellow, brown, or red hues. Gypsum forms mainly in sedimentary environments as evaporite deposits from the evaporation of sulfate-rich waters, and it can also occur as diagenetic infillings in sedimentary rocks; the anhydrous form, anhydrite (CaSO4), can dehydrate to gypsum under suitable conditions.

Common varieties include selenite, a transparent to translucent crystalline form; satin spar, which is fibrous and

Historically, gypsum has been used since ancient times in plastering and sculpture. The name gypsos reflects

silky
in
appearance;
and
alabaster,
a
fine-grained,
massive
variety
used
for
sculpture
and
ornament.
The
mineral
is
widely
mined
for
industrial
uses.
The
hydrated
calcium
sulfate
is
the
basis
of
plaster
of
Paris
and
many
construction
plasters,
as
well
as
plasterboard
and
molds
used
in
art
and
medicine.
Gypsum
is
also
used
as
a
soil
conditioner
and
as
a
set-regulator
in
Portland
cement.
its
long
recognition
in
the
Greek
world,
and
the
term
appears
in
archaeological
and
geological
literature.
Today,
gypsum
remains
a
common,
inexpensive
mineral
with
diverse
industrial
applications,
valued
for
its
workability,
abundance,
and
versatility.