Gypsum

gypsiferouscalcium sulfate dihydrategypseousgypseous soilsGypsum Fibrosumalabastercalcined gypsumcalcium sulphatedesulpho-gypsumG'''ypsum
Gypsum is a soft sulfate mineral composed of calcium sulfate dihydrate, with the chemical formula CaSO 4 ·2H 2 O.wikipedia
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Calcium sulfate

calcium sulphateCaSO 4 Drierite
Gypsum is a soft sulfate mineral composed of calcium sulfate dihydrate, with the chemical formula CaSO 4 ·2H 2 O. It is widely mined and is used as a fertilizer and as the main constituent in many forms of plaster, blackboard/sidewalk chalk, and drywall.
One particular hydrate is better known as plaster of Paris, and another occurs naturally as the mineral gypsum.

Drywall

plasterboardwallboardsheetrock
Gypsum is a soft sulfate mineral composed of calcium sulfate dihydrate, with the chemical formula CaSO 4 ·2H 2 O. It is widely mined and is used as a fertilizer and as the main constituent in many forms of plaster, blackboard/sidewalk chalk, and drywall. However, the unique conditions of the White Sands National Monument in the US state of New Mexico have created a 710 km2 expanse of white gypsum sand, enough to supply the US construction industry with drywall for 1,000 years.
Drywall (also known as plasterboard, wallboard, sheet rock, gypsum board, buster board, custard board, rusted sword, or gypsum panel) is a panel made of calcium sulfate dihydrate (gypsum), with or without additives, typically extruded between thick sheets of facer and backer paper, used in the construction of interior walls and ceilings.

Alabaster

Alabaster gypsumabovealabastar
A massive fine-grained white or lightly tinted variety of gypsum, called alabaster, has been used for sculpture by many cultures including Ancient Egypt, Mesopotamia, Ancient Rome, the Byzantine Empire, and the Nottingham alabasters of Medieval England.
The former use is in a wider sense that includes varieties of two different minerals: the fine-grained massive type of gypsum and the fine-grained banded type of calcite.

Selenite (mineral)

selenitesatin spargypsum flowers
Gypsum also crystallizes as translucent crystals of selenite. Gypsum occurs in nature as flattened and often twinned crystals, and transparent, cleavable masses called selenite.
Selenite, also known as satin spar, desert rose, or gypsum flower are four crystal structure varieties of the mineral gypsum.

Nottingham alabaster

Alabasteralabaster reliefsalabaster-carved tomb
A massive fine-grained white or lightly tinted variety of gypsum, called alabaster, has been used for sculpture by many cultures including Ancient Egypt, Mesopotamia, Ancient Rome, the Byzantine Empire, and the Nottingham alabasters of Medieval England.
Alabaster is a mineral composed of gypsum and various impurities, is much softer and easier to work than marble and a good material for mass production, though not suitable for outdoors use.

Evaporite

evaporitesevaporiticevaporite deposits
It also forms as an evaporite mineral and as a hydration product of anhydrite. Gypsum is a common mineral, with thick and extensive evaporite beds in association with sedimentary rocks.
At this point, the mineral gypsum begins to form, which is then followed by halite at 10%, excluding carbonate minerals that tend not to be evaporites.

Sculpture

sculptorsculpturessculpting
A massive fine-grained white or lightly tinted variety of gypsum, called alabaster, has been used for sculpture by many cultures including Ancient Egypt, Mesopotamia, Ancient Rome, the Byzantine Empire, and the Nottingham alabasters of Medieval England.
Alabaster or mineral gypsum is a soft mineral that is easy to carve for smaller works and still relatively durable.

Plaster

plaster of Parisgypsum plasterplaster-of-Paris
Gypsum is a soft sulfate mineral composed of calcium sulfate dihydrate, with the chemical formula CaSO 4 ·2H 2 O. It is widely mined and is used as a fertilizer and as the main constituent in many forms of plaster, blackboard/sidewalk chalk, and drywall. Because the quarries of the Montmartre district of Paris have long furnished burnt gypsum (calcined gypsum) used for various purposes, this dehydrated gypsum became known as plaster of Paris.
The most common types of plaster mainly contain either gypsum, lime, or cement, but all work in a similar way.

Mohs scale of mineral hardness

Mohs hardnessMohs scalehardness
The Mohs scale of mineral hardness defines hardness value 2 as gypsum based on scratch hardness comparison.

Blackboard

chalkboardchalkboardschalk board
Gypsum is a soft sulfate mineral composed of calcium sulfate dihydrate, with the chemical formula CaSO 4 ·2H 2 O. It is widely mined and is used as a fertilizer and as the main constituent in many forms of plaster, blackboard/sidewalk chalk, and drywall.
White chalk sticks are made mainly from calcium carbonate derived from mineral chalk rock or limestone, while colored or pastel chalks are made from calcium sulfate in its dihydrate form, CaSO 4 ·2H 2 O, derived from gypsum.

Desert rose (crystal)

desert roseRose rockdesert roses
In arid areas, gypsum can occur in a flower-like form, typically opaque, with embedded sand grains called desert rose.
Desert rose is the colloquial name given to rose-like formations of crystal clusters of gypsum or baryte which include abundant sand grains.

Montmartre

Montmartre QuarterMontmarteButte Montmartre
Because the quarries of the Montmartre district of Paris have long furnished burnt gypsum (calcined gypsum) used for various purposes, this dehydrated gypsum became known as plaster of Paris.
The abbey was destroyed in 1790 during the French Revolution, and the convent demolished to make place for gypsum mines.

Anhydrite

Gypsum karstanhydrideanhydrite stone
It also forms as an evaporite mineral and as a hydration product of anhydrite. As for anhydrite, its solubility in saline solutions and in brines is also strongly dependent on NaCl (common table salt) concentration.
When exposed to water, anhydrite readily transforms to the more commonly occurring gypsum, (CaSO 4 ·2H 2 O) by the absorption of water.

Spar (mineralogy)

sparfluorsparMicrosparry
The various spar minerals were a historical term among miners and alchemists for any nonmetallic mineral akin to gypsum, known in Old English as spærstān, spear stone, referring to its crystalline projections.

Brine

salt watersalt brinebrine water
As for anhydrite, its solubility in saline solutions and in brines is also strongly dependent on NaCl (common table salt) concentration.
Modification of seawater via evaporation results in the concentration of salts in the residual fluid, a characteristic geologic deposit called an evaporite is formed as different dissolved ions reach the saturation states of minerals, typically gypsum and halite.

Quarry

quarriesquarryingquarried
Because the quarries of the Montmartre district of Paris have long furnished burnt gypsum (calcined gypsum) used for various purposes, this dehydrated gypsum became known as plaster of Paris.

White Sands National Monument

White SandsNew Mexico's White Sands
However, the unique conditions of the White Sands National Monument in the US state of New Mexico have created a 710 km2 expanse of white gypsum sand, enough to supply the US construction industry with drywall for 1,000 years.
The monument is situated at an elevation of 4235 ft in the mountain-ringed Tularosa Basin and comprises the southern part of a 275 mi2 field of white sand dunes composed of gypsum crystals.

Scratch hardness

hardnessscratch
The Mohs scale of mineral hardness defines hardness value 2 as gypsum based on scratch hardness comparison.

Calcination

calcinedcalciningcalcine
Because the quarries of the Montmartre district of Paris have long furnished burnt gypsum (calcined gypsum) used for various purposes, this dehydrated gypsum became known as plaster of Paris.

Ancient Egypt

EgyptEgyptianAncient Egyptian
A massive fine-grained white or lightly tinted variety of gypsum, called alabaster, has been used for sculpture by many cultures including Ancient Egypt, Mesopotamia, Ancient Rome, the Byzantine Empire, and the Nottingham alabasters of Medieval England.
Embalmers used salts from the Wadi Natrun for mummification, which also provided the gypsum needed to make plaster.

Crystal twinning

twinningtwinnedtwins
Gypsum occurs in nature as flattened and often twinned crystals, and transparent, cleavable masses called selenite.
In the monoclinic system, twin occur most often on the planes {100} and {001} by the Manebach Law {001}, Carlsbad Law [001], Braveno Law {021} in orthoclase, and the Swallow Tail Twins {001} in gypsum.

Sedimentary rock

sedimentarysedimentary rockssediments
Gypsum is a common mineral, with thick and extensive evaporite beds in association with sedimentary rocks.
Common chemical sedimentary rocks include oolitic limestone and rocks composed of evaporite minerals, such as halite (rock salt), sylvite, baryte and gypsum.

Johann Friedrich Mayer (agriculturist)

Johann Friedrich MayerJohann F. MayerJohann Friderich Mayer
In this work he promoted the use of crushed gypsum as fertilization of fields, which he had found in the nearby Waldenburg Hills.

Fort Dodge, Iowa

Fort DodgeFort Dodge, IADodge
Large open pit quarries are located in many places including Fort Dodge, Iowa, which sits on one of the largest deposits of gypsum in the world, and Plaster City, California, United States, and East Kutai, Kalimantan, Indonesia.
In 1872 the long and continuing history of gypsum production in Iowa started when George Ringland, Webb Vincent, and Stillman T. Meservey formed the Fort Dodge Plaster Mills to mine, grind, and prepare gypsum for commercial use.

Sulfur

sulphurSbrimstone
It is often associated with the minerals halite and sulfur.
Native sulfur is synthesised by anaerobic bacteria acting on sulfate minerals such as gypsum in salt domes.