How to describe gypsum?

Medical plaster and plaster bandages have played a significant role in the history of treating bone fractures and other orthopedic conditions. They provide support and immobilization, promoting proper bone healing and restoration of limb function after various injuries. Modern medical plaster is usually made from plaster of Paris (calcium sulfate semi-aqueous), which is applied to a special fabric or paper base. Upon contact with water, the plaster hardens, which makes it possible to create a strong and stable structure that provides immobilization of the injured limb.

Types of plaster bandages and their use

• Traditional Plaster Bandage: A conventional bandage impregnated with plaster of Paris, which is simple and low cost.
• Synthetic plaster casts: Made from fiberglass or other synthetic materials, making them lighter and more comfortable, as well as waterproof.
• Semi-rigid cast: Used for protection for minor injuries and in cases where partial mobility is necessary.

Application methods

A plaster cast is applied to the affected area after comparing and fixing the bone fragments. Before applying the cast, the limb is wrapped with cotton wool or a special pad to protect the skin and prevent pressure.

The length of application depends on the type and severity of the fracture, the age of the patient, and, as a rule, can vary from several weeks to several months.

Efficiency control

The effectiveness of plaster application is assessed by x-ray examination at various periods of time after fixation of the fracture. Visual assessment and palpation are also performed to identify symptoms of complications such as swelling, discomfort or changes in skin color that indicate tissue compression.

Development of technologies for the production and use of gypsum

• Waterproof Pads: The development of waterproof pads makes it possible to shower or bathe while wearing a cast, which greatly improves patient comfort.
• Modern synthetic materials: Fiberglass and other synthetic materials make plaster casts lighter, stronger and more comfortable to wear, and also allow the skin to “breathe”.
• 3D Printing Technologies: Using 3D printing to create custom plaster casts provides a precise and comfortable fit.
• Colored and Patterned Plasters: The variety of colors and patterns has made plaster more aesthetically appealing, especially for children.
• Improved Rehabilitation: The development of casts with adjustable stiffness helps in faster and more effective rehabilitation after cast removal.

Manufacturers and medical researchers continue to look for ways to improve medical casts and their application techniques, which in the future could lead to an even more effective way to treat fractures and musculoskeletal injuries.

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The history of the appearance of plaster bandages

1. Tree bark and branches: Often used to create splints and immobilization, wrapping tree bark around a limb or attaching branches to stabilize bone.
2. Fabrics and leather: Damaged limbs were wrapped in strips of linen cloth or pieces of leather, which provided some degree of stiffness when dried.
3. Metal Plates: Metals were sometimes used to make tires, especially in later historical periods.
4. Clay and gypsum plaster: Some civilizations used clay and gypsum plaster to provide immobilization, which when set created a hard shell around the limb.
5. Impregnated Wool: There are records on cuneiform tablets indicating the use of wool splints impregnated with medicinal substances.
6. Papyrus and reeds: In Egypt, strips of papyrus, reeds, or other available plant materials may have been used for immobilization.

These methods, although effective to some extent, did not provide the same level of stabilization made possible by medical plaster. The use of gypsum in medicine began in 1852 thanks to the Dutch doctor Antonius Mathischen. He was the first to use plaster casts to provide permanent fixation for fractures.

Гипс – mineral, hydrous calcium sulfate. The fibrous variety of gypsum is called selenite, and the granular variety is called alabaster. One of the most common minerals; the term is also used to designate the rocks it consists of. Gypsum is also commonly called a building material obtained by partial dehydration and grinding of the mineral. The name comes from the Greek. gypsos, which in ancient times meant both plaster itself and chalk. A dense snow-white, cream or pink fine-grained variety of gypsum known as alabaster

1. Structure
2. Materials
3. Morphology
4. Origin
5. Application
6. Classification
7. physical properties
8. Optical properties
9. Crystallographic properties

STRUCTURE

Chemical composition – Ca[SO₄]×2H₂O. Monoclinic system. The crystal structure is layered; two sheets of anionic groups [SO₄] 2- , closely associated with Ca 2+ ions, form double layers oriented along the (010) plane. Molecules H₂O occupy spaces between these double layers. This easily explains the very perfect cleavage characteristic of gypsum. Each calcium ion is surrounded by six oxygen ions belonging to SO groups₄, and two water molecules. Each water molecule binds a Ca ion to one oxygen ion in the same bilayer and to another oxygen ion in the adjacent layer.

PROPERTIES

The color varies, but usually white, gray, yellow, pink, etc. Pure transparent crystals are colorless. Impurities can be painted in different colors. The color of the dash is white. The luster of the crystals is glassy, ​​sometimes with a pearlescent tint due to microcracks of perfect cleavage; in selenite it is silky. Hardness 2 (Mohs scale standard). The cleavage is very perfect in one direction. Thin crystals and fusion plates are flexible. Density 2,31 – 2,33 g/cm3.
It has noticeable solubility in water. A remarkable feature of gypsum is the fact that its solubility with increasing temperature reaches a maximum at 37-38°, and then drops quite quickly. The greatest decrease in solubility occurs at temperatures above 107° due to the formation of “hemihydrate” – CaSO₄ × 1/2H₂O.
At 107°C it partially loses water, turning into white alabaster powder (2CaSO₄ × H₂O), which is noticeably soluble in water. Due to the smaller number of hydration molecules, alabaster does not shrink during polymerization (increases in volume by approximately 1%). Under item tr. loses water, splits and fuses into white enamel. On coal in a reducing flame it produces CaS. In water acidified with H₂SO₄, dissolves much better than in pure. However, at the concentration of H₂SO₄ over 75 g/l. solubility drops sharply. Very slightly soluble in HCl.

MORPHOLOGY

Crystals, due to the predominant development of their faces, have a tabular, rarely columnar or prismatic appearance. Of the prisms, the most common are and, sometimes others. The faces and often have vertical shading. Fusion twins are common and come in two types: 1) Gallic by (100) and 2) Parisian by (101). It is not always easy to distinguish them from each other. Both of them resemble a dovetail. Gallic twins are characterized by the fact that the edges of the prism m are located parallel to the twin plane, and the edges of the prism l form an incoming angle, while in Parisian twins the edges of the prism I are parallel to the twin seam.
It occurs in the form of colorless or white crystals and their intergrowths, sometimes colored by inclusions and impurities captured by them during growth in brown, blue, yellow or red tones. Characteristic are intergrowths in the form of a “rose” and twins – the so-called. “swallowtails”). It forms veinlets of a parallel-fibrous structure (selenite) in clayey sedimentary rocks, as well as dense, continuous fine-grained aggregates resembling marble (alabaster). Sometimes in the form of earthy aggregates and cryptocrystalline masses. Also makes up the cement of sandstones.
Pseudomorphoses of calcite, aragonite, malachite, quartz, etc. on gypsum are common, as are pseudomorphs of gypsum on other minerals.

ORIGIN

A widespread mineral, it is formed in natural conditions in various ways. The origin is sedimentary (typical marine chemogenic sediment), low-temperature hydrothermal, found in karst caves and solfataras. Precipitates from sulfate-rich aqueous solutions during the drying out of sea lagoons and salt lakes. Forms layers, layers and lenses among sedimentary rocks, often in association with anhydrite, halite, celestine, native sulfur, sometimes with bitumen and oil. It is deposited in significant quantities by sedimentation in lake and sea salt-bearing dying pools. In this case, gypsum, along with NaCl, can be released only in the initial stages of evaporation, when the concentration of other dissolved salts is not yet high. When a certain value of salt concentration is reached, in particular NaCl and especially MgCl₂, instead of gypsum, anhydrite will crystallize and then other, more soluble salts, i.e. The gypsum in these basins must belong to earlier chemical sediments. Indeed, in many salt deposits, layers of gypsum (as well as anhydrite), interbedded with layers of rock salt, are located in the lower parts of the deposits and in some cases are underlain only by chemically precipitated limestones.

In Russia, thick gypsum-bearing strata of Permian age are distributed throughout the Western Urals, in Bashkiria and Tatarstan, in Arkhangelsk, Vologda, Gorky and other regions. Numerous deposits of Upper Jurassic age are established in the North. Caucasus, Dagestan. Remarkable collection samples with gypsum crystals are known from the Gaurdak deposit (Turkmenistan) and other deposits in Central Asia (in Tajikistan and Uzbekistan), in the Middle Volga region, in the Jurassic clays of the Kaluga region. In the thermal caves of Naica Mine, (Mexico), druses of uniquely sized gypsum crystals up to 11 m long were found.

APPLICATION

Today, the mineral “gypsum” is mainly a raw material for the production of α-gypsum and β-gypsum. β-gypsum (CaSO₄· 0,5H₂O) – powdered binder material obtained by heat treatment of natural dihydrate gypsum CaSO₄· 2H₂O at a temperature of 150-180 degrees in devices communicating with the atmosphere. The product of grinding β-modification gypsum into a fine powder is called building gypsum or alabaster; with finer grinding, molding gypsum is obtained or, when using high-purity raw materials, medical gypsum.

During low-temperature (95-100 °C) heat treatment in hermetically sealed apparatus, α-modification gypsum is formed, the grinding product of which is called high-strength gypsum.

When mixed with water, α and β-gypsum hardens, turning back into gypsum dihydrate, with the release of heat and a slight increase in volume (by approximately 1%), however, such secondary gypsum stone already has a uniform fine-crystalline structure, the color of various shades of white (depending on raw materials), opaque and microporous. These properties of gypsum are used in various fields of human activity.

Molecular weight	172.17 g / mol
Origin of the name	From the Greek γύψος (gyps) meaning “chalk” or “plaster”, “burned” mineral.
IMA status	valid

CLASSIFICATION

Strunz (8th edition)	6/C.22-20
Nickel-Strunz (10th edition)	7.CD.40
Dana (7th edition)	29.6.3.1
Dana (8th edition)	29.6.3.1
Hey’s CIM Ref.	25.4.3

PHYSICAL PROPERTIES

Mineral color	colorless turning to white, often colored by impurity minerals yellow, pink, red, brown, etc.; sometimes sectorial-zonal coloring or distribution of inclusions across growth zones inside crystals is observed; colorless in internal reflexes and at random.
Line color	white
Transparency	transparent, translucent, opaque
Brilliance	glassy, ​​close to glassy, ​​silky, pearlescent, dull
Cleavage	very perfect, easily obtained, almost mica-like in some samples; clear, turning into a conchoidal fracture; by, gives a splintered fracture
Hardness (Mohs scale)	2
Kink	smooth, conchoidal
Strength	flexible
Density (measured)	2.312 – 2.322 g/cm 3
Radioactivity (GRapi)	0

OPTICAL PROPERTIES

Type	biaxial(+)
Refractive indices	nα = 1.519 – 1.521 nβ = 1.522 – 1.523 nγ = 1.529 – 1.530
Maximum birefringence	d = 0.010
Optical relief	low
Pleochroism	does not pleochroate
Diffusion	strong r > v oblique
Luminescence in ultraviolet radiation	fluorescent, orange-yellow

CRYSTALLOGRAPHIC PROPERTIES

Point group	2/m – Monoclinic-prismatic
Space group	A2/a
Syngonia	monoclinic
Cell Options	a = 5.679(5) Å, b = 15.202(14) Å, c = 6.522(6) Å, β = 118.43°
Morphology	from thin to thick flat crystals, with and ; crystals may be distorted, bent or twisted
Twinning	(“dovetail”), very often, with an incoming angle, usually formed by ; by as contact twins (“butterfly” or “heart-shaped”), as well as by ; like cruciform penetrating twins