Gypsum stone - its properties and applications. Physical properties, varieties and photos of gypsum

Gypsum

Gypsum (eng. G ypsum) - a mineral, aqueous calcium sulfate. The chemical composition is Ca × 2H 2 O. The syngony is monoclinic. The crystal structure is layered; two sheets of 2- anionic groups closely associated with Ca 2+ ions form double layers oriented along the (010) plane. Molecules of H 2 O occupy places 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 the SO 4 groups and two water molecules. Each water molecule binds a Ca ion to one oxygen ion in the same double layer and to another oxygen ion in the adjacent layer.

Properties

The color is very different, but usually white, gray, yellow, pink, etc. Pure transparent crystals are colorless. Impurities can be dyed in different colors. The dash color is white. The luster of the crystals is glassy, ​​sometimes with a mother-of-pearl tint due to microcracks of perfect cleavage; selenite is silky. Hardness 2 (standard Mohs scale). Cleavage is very perfect in one direction. Thin crystals and cleavage plates are flexible. Density 2.31 - 2.33 g / cm 3.
It has significant solubility in water. A remarkable feature of gypsum is the fact that its solubility reaches a maximum at 37-38°C with increasing temperature, and then drops rather quickly. The greatest decrease in solubility is established at temperatures above 107 ° due to the formation of a "hemihydrate" - CaSO 4 × 1/2H 2 O.
At 107 o C, it partially loses water, turning into a white alabaster powder, (2CaSO 4 × H 2 O), which is noticeably soluble in water. Due to the smaller number of hydrate molecules, alabaster does not shrink during polymerization (increases in volume by approx. 1%). Under p. tr. loses water, splits and fuses into white enamel. On charcoal in a reducing flame it gives CaS. It dissolves much better in water acidified with H 2 SO 4 than in pure water. However, at a concentration of H 2 SO 4 over 75 g/l. solubility drops sharply. Very slightly soluble in HCl.

Location forms

Due to the predominant development of (010) faces, crystals have a tabular, rarely columnar, or prismatic appearance. Of the prisms, (110) and (111) are the most common, sometimes (120) and others. Faces (110) and (010) often have vertical shading. Intergrowth twins are frequent and are of two types: 1) Gallic according to (100) and 2) Parisian according to (101). It is not always easy to tell them apart. Both of them resemble a dovetail. Gallic twins are characterized by the fact that the edges of the prism m (110) are parallel to the twin plane, and the edges of the prism l (111) form a reentrant angle, while in the Parisian twins the edges of the prism Ι (111) 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. Intergrowths in the form of a "rose" and twins are characteristic - the so-called. "dovetails"). It forms veinlets of a parallel fibrous structure ( selenite) in clay sedimentary rocks, as well as dense solid fine-grained aggregates resembling marble ( alabaster). Sometimes in the form of earthy aggregates and cryptocrystalline masses. It also forms the cement of sandstones.

Common are pseudomorphs after gypsum of calcite, aragonite, malachite, quartz, etc., as well as pseudomorphs of gypsum after other minerals.

Origin

A widely distributed mineral, it is formed in natural conditions in various ways. Sedimentary origin (typical marine chemogenic sediment), low-temperature hydrothermal, found in karst caves and solfataras. It precipitates from sulfate-rich aqueous solutions during the drying of sea lagoons and salt lakes. Forms layers, interlayers and lenses among sedimentary rocks, often in association with anhydrite, halite, celestine, native sulfur, sometimes with bitumen and oil. In significant masses, it is deposited by sedimentation in lacustrine and marine salt-bearing dying basins. 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. Upon reaching a certain value of salt concentration, in particular NaCl and especially MgCl 2 , anhydrite will crystallize instead of gypsum and then other, more soluble salts, i.e. the gypsum in these basins must belong to the 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.
Significant masses of gypsum in sedimentary rocks are formed primarily as a result of the hydration of anhydrite, which in turn precipitated during the evaporation of sea water; often, during its evaporation, gypsum is deposited directly. Gypsum results from the hydration of anhydrite in sediments under the influence of surface water under conditions of low external pressure (on average, to a depth of 100-150m.) According to the reaction: CaSO 4 + 2H 2 O = CaSO 4 × 2H 2 O. In this case, strong an increase in volume (up to 30%) and, in connection with this, numerous and complex local disturbances in the conditions of occurrence of gypsum-bearing strata. Most of the large deposits of gypsum on the globe arose in this way. Nests of large, often transparent crystals are sometimes found in voids among solid gypsum masses.
Can serve as cement in sedimentary rocks. Gypsum vein is usually the product of the reaction of sulfate solutions (formed by the oxidation of sulfide ores) with carbonate rocks. It is formed in sedimentary rocks during the weathering of sulfides, under the influence of sulfuric acid formed during the decomposition of pyrite on marls and calcareous clays. In semi-desert and desert areas, gypsum is very often found in the form of veins and nodules in the weathering crust of rocks of various compositions. In the soils of the arid zone, new formations of redeposited gypsum are formed: single crystals, twins (“dovetails”), druses, “gypsum roses”, etc.
Gypsum is fairly well soluble in water (up to 2.2 g/L), and with an increase in temperature, its solubility first increases, and falls above 24°C. Due to this, gypsum, when deposited from sea water, is separated from halite and forms independent layers. In semi-deserts and deserts, with their dry air, sharp daily temperature drops, saline and gypsum soils, in the morning, with an increase in temperature, gypsum begins to dissolve and, rising in solution by capillary forces, is deposited on the surface when water evaporates. By evening, with a decrease in temperature, crystallization stops, but due to lack of moisture, the crystals do not dissolve - in areas with such conditions, gypsum crystals are found in especially large quantities.

Location

In Russia, thick gypsum-bearing strata of Permian age are distributed in the Western Urals, in Bashkiria and Tatarstan, in Arkhangelsk, Vologda, Gorky and other regions. Numerous deposits of the Upper Jurassic age are established in the North. Caucasus, Dagestan. Remarkable collection specimens 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), druze of gypsum crystals of unique size up to 11 m long were found.

Application

Fibrous gypsum (selenite) is used as an ornamental stone for inexpensive jewelry. Since ancient times, large jewelry items have been carved from alabaster - interior items (vases, countertops, inkwells, etc.). Calcined gypsum is used for castings and casts (bas-reliefs, cornices, etc.), as a binder in the construction industry, in medicine.
It is used to obtain building gypsum, high-strength gypsum, gypsum-cement-pozzolanic binder.

• Gypsum is also called sedimentary rock, composed mainly of this mineral. Its origin is evaporite.

Gypsum (eng. GYPSUM) - CaSO 4 2H 2 O

Other names, varieties

silky spar,
Ural eolinit,
gypsum spar,
girlish or marino glass.

• English - Gypsum
• Arabic - جص
• Bulgarian - Gypsum
• Hungarian - Gipsz
• Dutch - Gips
• Greek - Γύψος
• Danish - Gips
• Hebrew - גבס
• Spanish - Yeso; Gypsita; Oulopholita
• Italian - Gesso;Acidovitriolosaturata;Geso
• Catalan - Guix
• Korean - 석고
• Latvian - Ģipsis
• Latin - Gypsum
• Lithuanian - Gipsas
• German - Gips;Atlasgips;Gipsrose;Gyps;Gypsit;Oulopholit
• Polish - Gips
• Portuguese - Gipsita
• Romanian - Gips
• Russian - Gypsum
• Slovak - Sadrovec
• Slovenian - Sadra
• French - Gypse;Chaux sulfatee
• Croatian - Gips
• Czech - Sadrovec
• Swedish - Gips
• Esperanto
• Estonian - Kips
• Japanese - 石膏

Name: Gypsum

Color: colorless turning into white, often colored by minerals-impurities in yellow, pink, red, brown, etc.; sometimes there is a sectorial-zonal color or distribution of inclusions over growth zones inside the crystals; colorless in internal reflexes and translucent..

"Gypsum" - has an old Greek origin and was used to refer to fired gypsum or alabaster

Gypsum is a widespread rock-forming miner of sedimentary rocks.

Chemical composition

CaO - 32.57%, SO3 - 46.50%, H2O - 20.93%. Usually clean. In the form of mechanical impurities, the following are established: clay substance, organic substances (odorous gypsum), inclusions of grains of sand, sometimes sulfides, etc.

Varieties
1. Selenite - fibrous gypsum with a silky sheen. It is used to designate translucent gypsum, showing peculiar moon-like light reflections.

Crystallographic characteristic

Syngony monoclinic

Prismatic class c. With. L2PC. Etc. gr. A2/n (C 6 2h). a0 = 10.47; b0 = 15.12; c0 = 6.28; β = 98°58′. Z = 4.

Crystal structure

According to X-ray data, the layered structure of this mineral is clearly visible. Two sheets of anionic groups 2–, closely associated with Ca2+ ions, form double layers oriented along the (010) plane. H2O molecules occupy spaces between these double layers. This easily explains the very perfect cleavage, so characteristic of gypsum. Each calcium ion is surrounded by six oxygen ions belonging to the SO4 groups and two water molecules. Each water molecule binds a Ca ion to one oxygen ion in the same double layer and to another oxygen ion in the adjacent layer.

Primary Forms: Crystal Form. Crystals, due to the predominant development of faces (010), have a tabular, rarely columnar or prismatic appearance. Of the prisms, (110) and (111) are the most common, sometimes (120) and others. Faces (110) and (010) often have vertical shading.

The form of finding gypsum in nature

Shape of crystals. Forms thick and thin tabular crystals

Often doubles are characteristic in appearance - the so-called "dovetails".

Fusion twins are common and come in three types:

1. Gallic contact twins by (100),
2. Parisian contact doubles by (101)
3. cruciform twins of germination according to (209) are less common. It is not always easy to tell them apart.

The first two types resemble a dovetail.
Gallic twins are characterized by the fact that the edges of the prism m(110) are parallel to the twin plane, and the edges of the prism l(111) form a reentrant angle, while in the Parisian twins the edges of the prism l(111) are parallel to the twin seam.

Physical properties of gypsum

Aggregates. It occurs in the form of dense (alabaster), granular, earthy, foliar and fibrous aggregates (satin spar), twisted crystals, concretions and pulverized masses.

In voids it occurs in the form of drusen crystals.

In the cracks, asbestos-like parallel-fibrous masses of gypsum with a silky sheen and the location of the fibers perpendicular to the walls of the cracks are sometimes observed. In the Urals gypsum called selenite. In those cases when gypsum crystallizes in loose sandy masses, it contains many trapped sand grains in its environment, clearly visible on the cleavage planes of large crystalline individuals (the so-called Repetek gypsum).

Optical

• Gypsum color is white. Individual crystals are often water-clear and colorless. It is also colored in gray, honey-yellow, red, brown and black colors (depending on the color of impurities captured during crystallization).
• The line is white.
• Glass luster.
• The ebb on the cleavage planes is mother-of-pearl; dull, in fibrous varieties - silky.
• Transparent or translucent.
• The refractive indices Ng = 1.530, Nm = 1.528 and Np = 1.520. Nm = b; (+)2V = 58°, s: Ng = 52°. Strong dispersion r > u (001).

Mechanical

• Hardness 2 (scratched with a fingernail). Very fragile.
• Density 2.32.
• Cleavage according to (010) is very perfect, according to (100), corresponding to layers of H2O molecules; and (011) clear; solder pins have a rhombic shape with angles of 66 and 114°.
• The fracture is stepped, granular, splintery.
• Slip planes (010)

Chemical properties

It has significant solubility in water. A remarkable feature of gypsum is the fact that its solubility reaches a maximum at 37–38 °C with increasing temperature, and then drops rather quickly. The greatest decrease in solubility is established at temperatures above 107 ° C due to the formation of "hemihydrate" - Ca. 1/2 H2O.

It dissolves much better in water acidified with H2SO4 than in pure water. However, at H2SO4 concentrations above 75 g/l, the solubility drops sharply. Very slightly soluble in HCl.

Diagnostic signs

Similar minerals

It is well diagnosed by low hardness (scratched with a fingernail) and very perfect cleavage. By cleavage, thin leaves can be split off. Leaves are flexible. Similar to anhydrite, but softer and unlike it is scratched with a fingernail.

Crystalline gypsum is characterized by a very perfect cleavage along (010) and low hardness (it is scratched with a fingernail). Dense marbled aggregates and fibrous masses are also recognizable by their low hardness and the absence of CO2 bubbles when wetted with HCl.

Associated minerals. Halite, anhydrite, sulfur, calcite.

Origin and location

Gypsum under natural conditions is formed in various ways.

• In significant masses, it is deposited by sedimentation in lacustrine marine salt-bearing dying basins. 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 still low. Upon reaching a certain value of the concentration of salts, in particular NaCl and especially MgCl2, anhydrite will crystallize instead of gypsum, followed by other, more soluble salts. Consequently, the gypsum in these basins must belong to the 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.
• Quite significant masses of gypsum arise as a result of anhydrite hydration in sedimentary deposits under the influence of surface waters under conditions of low external pressure (on average, to a depth of 100–150 m) according to the reaction: CaSO4 + 2H2O = CaSO4 . 2H2O

In this case, there is a strong increase in volume (up to 30%) and, in connection with this, numerous and complex local disturbances in the conditions of occurrence of gypsum-bearing strata. Most of the large deposits of gypsum on the globe arose in this way. In voids among solid gypsum masses, sometimes there are nests of coarse-grained, often transparent crystals (“feldspar gypsum”).

• In semi-desert and desert areas, gypsum is very often found in the form of veins and nodules in the weathering crust of rocks of various compositions. It is also often formed on limestones under the action of waters enriched with sulfuric acid or dissolved sulfates. It occurs, finally, in the zones of oxidation of sulfide deposits, but not in such large quantities as one might expect. The fact is that in the vast majority of cases pyrite or pyrrhotite are present in sulfide ores in one amount or another, the oxidation of which (especially the first one) significantly increases the content of sulfuric acid in surface waters. Water acidified with sulfuric acid significantly increases the solubility of gypsum. Therefore, in a number of deposits, gypsum is more common in the upper parts of primary ore zones, where it occurs in cracks together with other sulfates.
• Relatively rarely, gypsum is observed as a typical hydrothermal mineral in sulfide deposits formed under conditions of low pressures and temperatures. In these deposits, it is sometimes observed as large crystals in voids and contains inclusions of chalcopyrite, pyrite, sphalerite, and other minerals. Pseudomorphoses on gypsum of calcite, aragonite, malachite, quartz and other minerals, as well as pseudomorphoses of gypsum on other minerals, have been repeatedly established.

A rare example of endogenous (hydrothermal) gypsum is transparent single-crystal masses that have grown over the brushes of zeolite crystals in the cavities of gabbroids of the Talnakh deposit (Norilsk group, Krasnoyarsk Territory).

A typical marine chemical sediment. By origin and presence in nature, it is closely related to anhydrite. It can be formed during the dehydration of anhydrite. It is also formed in the zone of weathering of sulfides and native sulfur (the so-called gypsum hats). Like anhydrite, gypsum can sometimes be of hydrothermal origin, occurring in products of fumarole activity.

Place of Birth

Sedimentary deposits of gypsum are distributed throughout the globe and are associated with deposits of various ages. We will not stop at listing them. Let us only point out that on the territory of Russia, thick gypsum-bearing strata of Permian age are distributed in the Western Urals, in Bashkiria and Tataria, Arkhangelsk, Vologda, Nizhny Novgorod and other regions. Numerous Late Jurassic deposits are established in the North Caucasus, Dagestan, Turkmenistan, Tajikistan, Uzbekistan, etc.

Its deposits are well known in the Girgenti region, Sicily; in the Paris Basin, France; in Northern Germany; near Krakow, Poland; in Salzburg, Austria; in Chihuahua, Mexico; in the states of New York and Michigan, USA; in the provinces of Ontario and New Brunswick (Hillsborough), Canada, and elsewhere.

Practical use

The practical value of gypsum is great, especially in the construction business.

1. Model or stucco (semi-baked) gypsum is used to obtain castings, gypsum casts, moldings for cornices, plaster ceilings and walls, in surgery, paper production when making thick white grades of paper, etc. In the construction industry, it is used as cement in brick and masonry , for printed floors, making bricks, slabs for window sills, stairs, etc.
2. Raw (natural) gypsum finds application mainly in the cement industry as an additive to Portland cement, stone material for sculpting statues, various handicrafts (especially Ural selenite), in the production of paints, enamel, glaze, in the metallurgical processing of oxidized nickel ores, etc.

It is used in the production of binding building minerals (building gypsum, alabaster - semi-fired gypsum, cement), in medicine, in the paper industry, as a fertilizer. Selenite is used as an inexpensive ornamental stone.

Physical research methods

Differential thermal analysis. Losing water turns into anhydrite (dehydration).

Gypsum dehydration occurs gradually; first it turns into Ca hemihydrate * 0.5H2O, then into soluble anhydrite y-Ca, then into insoluble anhydrite (i-Ca and, finally, at a temperature above 1500 ° into a probable modification

When heated under conditions of atmospheric external pressure, as thermograms show, gypsum begins to lose water at 80–90 ° C, and at temperatures of 120–140 ° C it completely turns into a hemihydrate, the so-called model, or plaster, gypsum (alabaster). This hemihydrate, mixed with water into a semi-liquid dough, soon hardens, expanding and releasing heat.

Gypsum has been known since antiquity, but still has not lost its popularity, even many modern materials cannot compete with it. It is used in the construction, porcelain, ceramics, oil and medicine industries.

Description of building material

Gypsum is made from gypsum stone. To obtain gypsum powder, the stone is fired in rotary kilns and then ground to form a powder. Most of all, gypsum is used in construction.

Walls plastered with gypsum mortar are able to absorb excess moisture and release it when the air is too dry.

Gypsum formula

The name gypsum comes from the Greek word gipsos. This material belongs to the class of sulfates. Its chemical formula is CaSO4?2H2O.

There are two types of gypsum:

1. Fibrous - selenite;
2. Grainy - alabaster.

Photo varieties of gypsum

Selenite Alabaster

Specifications and properties

For all gypsum mixtures, the technical characteristics are very similar, let's dwell on the properties and features of building gypsum.

These include:

• Density. Gypsum has a dense fine-grained structure. The true density is 2.60-2.76 g / cm?. In a loosely poured form, it has a density of 850-1150 kg / m?, and in a compacted form, the density is 1245-1455 kg / m?.
• How much to dry. The advantages of gypsum include fast setting and hardening. Gypsum seizes in the fourth minute after mixing the solution, and after half an hour it completely hardens. Therefore, the finished gypsum mortar must be used up immediately. To slow down the setting, water-soluble animal glue is added to the plaster.
• Specific gravity. The specific gravity of gypsum is measured in kg/m? in the ICSC system. Since the ratio of mass is equal to the volume it occupies, the specific, volumetric and bulk density of gypsum is approximately the same.
• What temperature can it withstand melting temperature). Gypsum can be heated to t 600-700°C without destruction. The fire resistance of gypsum products is high. Their destruction occurs only six to eight hours after exposure to high temperature.
• Strength. Building gypsum in compression has a strength of 4-6 MPa, high-strength - from 15 to 40 MPa or more. In well-dried samples, the strength is two to three times higher.
• GOST. State standard for gypsum 125-79 (ST SEV 826-77).
• Thermal conductivity. Gypsum is a poor conductor of heat. Its thermal conductivity is 0.259 kcal/m deg/h in the range from 15 to 45°C.
• Solubility in water. R dissolves in small quantities: 2.256 g dissolves in 1 liter of water at 0 °, 2.534 g at 15 °, 2.684 g at 35 °; further heating decreases the solubility again.

The video tells about building gypsum, how you can improve its properties, giving additional strength:

Varieties of gypsum

Gypsum has the greatest variety of objects of application among other binders. It allows you to save on other materials. There are many varieties of gypsum.

Building

It is used for the production of gypsum parts, partition boards for plastering. Work with gypsum mortar must be carried out in a very short time - from 8 to 25 minutes, it depends on the type of gypsum. During this time, it must be completely used up. At the beginning of hardening, gypsum is already gaining about 40% of its final strength.

Since cracks do not form on gypsum during hardening, when mixing the mortar with lime mortar, which gives it plasticity, various aggregates can be omitted. Due to the short setting time, hardening retarders are added to the gypsum. Building gypsum reduces labor intensity and construction costs.

At deposits by undermining gypsum-containing rocks. Further, the ore is transported to the factories in the form of gypsum stones.

high strength

In terms of chemical composition, high-strength gypsum is similar to building gypsum. But building gypsum has smaller crystals, while high-strength gypsum has large ones, so it has less porosity and very high strength.

High-strength gypsum is made by heat treatment in a sealed apparatus, where a gypsum stone is placed.

The scope of high-strength gypsum is extensive. Various building mixtures are prepared from it, fireproof partitions are built. It is also used to make various forms for the production of porcelain and faience sanitary ware. High-strength gypsum is used in traumatology and dentistry.

Polymeric

Orthopedists and traumatologists are more familiar with synthetic polymeric gypsum; gypsum bandages are produced on its basis for applying bandages for fractures.

Advantages of polymer plaster bandages:

1. three times lighter than conventional gypsum;
2. easy to apply;
3. allow the skin to breathe, as they have good permeability;
4. resistant to moisture;
5. allow you to control the fusion of bones, as they are permeable to x-rays.

cellacast

Bandages are also made from this plaster, their structure allows the bandage to stretch in all directions, so very complex bandages can be made from it. Cellacast has all the properties of a polymer bandage.

Sculptural or molding

This is the most high-strength gypsum, it does not contain any impurities, it has a high natural whiteness. It is used for making molds for sculptures, plaster figurines, molding souvenirs, in the porcelain and faience, aviation and automotive industries.

This is the main component of dry putty mixtures. Molding gypsum is obtained from building gypsum, for this it is additionally sifted and ground.

Known for several centuries, in our time it is still relevant. The most common rosettes of their gypsum, they are easy to make with your own hands.

Acrylic

Acrylic gypsum is made from water-soluble acrylic resin. After hardening, it looks like ordinary gypsum, but much lighter. Stucco molding on the ceiling and other decorative details are made from it.

Acrylic gypsum is frost-resistant, has a slight moisture absorption, so it can be used to finish building facades, creating interesting design solutions.

Working with acrylic plaster is very simple. If a little marble chips or aluminum powder or other inert fillers are added to the solution, acrylic gypsum products will very much resemble marble or metal ones.

It looks like acrylic gypsum

Polyurethane

Gypsum stucco can also be made from polyurethane or polystyrene gypsum. It costs much less than ordinary gypsum, and in terms of its qualities it almost does not differ from it.

White

With the help of white gypsum, seams, cracks are sealed, stucco molding is made and other types of construction and repair work are carried out. It has compatibility with various kinds of building materials. Hardening time of white gypsum 10 min.

fine-grained

Fine-grained gypsum is also called translucent. They fill the seams, joints in the plates, etc.

Liquid

Liquid gypsum is made from gypsum powder.

It is prepared according to the following technology:

• Pour water in the required amount.
• Gypsum is poured and immediately mixed.
• The density of the solution can be made different. A liquid solution is made to fill molds

Waterproof (moisture resistant)

Waterproof gypsum is obtained by processing raw materials using a special technology. To improve the properties of gypsum, vinasse is added to it - a waste from the production of ethyl alcohol.

Refractory

Gypsum is a non-combustible material, but gypsum boards made from it are quite combustible. To give them fire resistance, tongue-and-groove gypsum is used. It is used wherever it is required to increase fire resistance.

Architectural

Architectural gypsum does not contain toxic components, it is very plastic. Its acidity is similar to that of human skin. Classical plaster molding is very popular with designers, the demand for it is very high.

It requires certain knowledge, so you should first carefully study the features of such work, and only then move on to practice.

Stamps

Gypsum marking is carried out after testing standard samples of sticks for bending and compression two hours after their molding. According to GOST 129-79, twelve grades of gypsum are established, with strength indicators from G2 to G25.

Gypsum substitute

An analogue of gypsum is a fine powder of grayish white color - alabaster. It is also popular in construction. Alabaster is obtained from natural gypsum dihydrate by heat treatment at a temperature of 150 to 180? Outwardly, alabaster and gypsum are no different from each other.

Alabaster plaster walls and ceilings with low humidity in the room. Gypsum panels are produced from it.

What is the difference between gypsum and alabaster

Gypsum and alabaster have the following differences:

1. Alabaster is more limited in application, as it is used only in the construction industry. Gypsum is also used in medicine.
2. Alabaster dries instantly, so without the addition of special substances it is not suitable.
3. Gypsum is safer for the environment and human health.
4. Alabaster has a greater hardness than gypsum.

Hello, dear readers of the Sprint-Answer website. Today we have September 2, 2017, which means that the popular TV game “Who Wants to Be a Millionaire?” is on the air of Channel One. In this article you can read the review of the game, as well as find out all the answers in today's game "Who Wants to Be a Millionaire?" for 02.09.2017.

Our favorite colleagues of Dmitry Dibrov are visiting us today: Vladimir Gomelsky and Dmitry Borisov . These comrades of the procedure know how hard it is to make money on television, especially on the first channel, but they did not come to work, but to relax. But these guys are very confident if they named a fireproof amount of 400,000 rubles, at least they intend to answer 12 questions. Let's see what will come of it.

1. What are the long shorts called?

• canaries
• Maldives
• bermuda shorts
• Kuriles

2. What fictional creature has recently become a popular internet meme?

• Chatterbox
• Howler
• Munchkin
• Zhdun

3. What is the name of the species of butterflies?

• orange blossom
• lemongrass
• grapefruit
• kumquat

4. The name of which plant is the same as the nickname of the hero Fenimore Cooper?

• St. John's wort
• immortelle
• kalanchoe
• burdock

5. What was the first height in the pole vault that Sergey Bubka reached?

• 5 meters
• 6 meters
• 7 meters
• 8 meters

6. What is the name of the administrative-territorial unit of Germany?

• the fire
• Earth
• air

7. What prevents fluid from flowing out of the high pressure cylinder in a hydraulic jack?

• collar
• button
• cuff
• strap

8. What faculty did Rodion Raskolnikov study at?

• medical
• legal
• philosophical
• mathematical

9. Which character is missing from the wedding in the classic production of Sleeping Beauty?

• red Riding Hood
• Puss in Boots
• Thumb boy
• Blue Beard

10. What do sailors often call the "Marusin belt"?

• ribbon caps
• waterline
• anchor chain
• deck railing

11. What group of instruments does the Australian didgeridoo belong to?

• wind
• strings
• drums
• keyboards

12. Who became the first full Cavalier of St. George in Russia?

• Kutuzov
• Golitsyn
• Suvorov
• Menshikov

13. Who or what did the Parisian couriers secretly put into the newly appeared mailboxes so as not to be left without work?

• mice
• nettle
• embers

14. What mineral forms a beautiful transparent variety of "marino glass"?

• mica
• spinel
• gypsum
• cinnabar

Unfortunately, the players did not manage to correctly answer the fourteenth question, but they managed to win a fireproof amount. Therefore, the players' payoff in the game "Who wants to be a millionaire?" for September 9, 2017 amounted to 400,000 rubles.

The second part of today's game "Who wants to be a millionaire?" has begun, in which Olga Prokofieva and Valery Garkalin . The players chose a fireproof amount of 100,000 rubles.

1. What do they say about a person who does not want to tell anything?

• how to look into the water
• like water off a duck's back
• seventh water on jelly
• got water in his mouth

2. How does a hockey match start?

• from throwing out
• from a throw-in
• from a toss
• from the offering

3. What do men say they love?

• lips
• teeth
• eyes
• brains

4. What is the name of a young worker, trainee?

• trainee
• major
• boyfriend
• editor

5. What expression can define folklore?

• from hand to hand
• in a personal meeting
• word of mouth
• from foot to foot

6. What position did Gerasim, the hero of Turgenev's story "Mumu" hold in the manor house?

• blacksmith
• groom
• street cleaner
• coachman

7. What should a perlustrator do on duty?

• make chandeliers
• read letters
• illustrate books
• put people out of work

8. Which name is not usually shortened to the diminutive Seva?

Gypsum is one of the most common minerals in the world. It is mined from the bowels of the earth everywhere and is widely used in industry, the construction industry, and medicine. In our article you will find a detailed description and photo of the gypsum mineral. In addition, you will learn about the main areas of its application.

Mineral gypsum: description and chemical composition

The rock as well as the corresponding building material comes from the Greek word gipsos ("chalk"). Humanity has known about gypsum since ancient times. It has not lost its popularity even today.

Gypsum is a soft mineral. By the way, it is a reference for the Mohs scale of relative hardness, adopted at the beginning of the 19th century (hardness - 1.5-2.0).

According to the chemical composition, the mineral gypsum is an aqueous calcium sulfate. Its structure includes elements such as calcium (Ca), sulfur (S) and oxygen (O). Let's describe the chemical composition of gypsum in more detail:

• sulfur trioxide, SO 3 - 46%;
• calcium oxide, CaO - 33%;
• water, H 2 O - 21%.

Genetic classification: monoclinic syngony. This mineral is distinguished by a layered crystalline structure and a very perfect cleavage (single thin “petals” can be easily split off from it).

Mineral gypsum: properties and distinguishing features

Here are the main physical characteristics of gypsum by which it can be distinguished from other minerals:

• the fracture is uneven but flexible;
• gloss: from glass to silky or matte;
• hardness: low (easily scratched with a fingernail);
• the mineral slowly dissolves in water;
• not greasy to the touch;
• leaves behind a clearly visible white line;
• color: from white to gray (sometimes it can be pink).

Gypsum does not react with acids, but dissolves in hydrogen chloride (HCl). It can have different transparency, although the transparent mineral gypsum is more common in nature. When heated above 107 degrees Celsius, gypsum turns into alabaster, which, in turn, hardens when wetted with water.

Gypsum is often confused with anhydrite. These two minerals can be distinguished from each other by hardness (the second is much harder than the first).

The genesis of the mineral and its distribution in nature

Gypsum is a typical mineral of sedimentary origin. Most often, it is formed from natural aqueous solutions (for example, at the bottom of drying seas and reservoirs). The mineral gypsum can also accumulate in weathering zones of native sulfur and sulfides. In this case, the so-called gypsum hats are formed - loose or compacted rock masses contaminated with numerous impurities.

The gypsum is often found accompanied by sand, rock salt, anhydrite, sulfur, limestone and iron. Neighborhood with the latter, as a rule, gives it a brownish tint.

In nature, gypsum occurs in the form of elongated and prismatic crystals. It also often forms dense, scaly, fibrous, or "tablet" aggregations. Often gypsum is presented in the form of so-called roses or swallowtails.

The main varieties of the mineral

Geologists distinguish several dozen varieties of gypsum. The mineral can be fibrous, satiny, dense, foamy, fine-grained, boney, cubic, etc.

The main varieties of gypsum include:

• selenite;
• alabaster;
• "marino glass".

Selenite is a translucent mineral with a silky sheen. The name comes from the Greek word selena - "moon". This mineral is indeed distinguished by a slightly bluish tint. Selenite is used as an ornamental stone in the manufacture of budget jewelry.

Alabaster is a soft, easily destructible white material, a product of gypsum dehydration. It is widely used in the production of garden sculptures, vases, countertops, moldings and other interior items.

"Maryino glass" (maiden's or ladies' ice) is another type of gypsum, a transparent mineral with a mother-of-pearl or colored tint. It has a unique crystal lattice structure. In the old days, "Maryino glass" was widely used in the design of icons and holy images.

The main deposits of gypsum

The mineral gypsum is ubiquitous in the earth's crust. Its deposits are found in deposits of almost all periods of the geological history of the planet - from the Cambrian to the Quaternary. Deposits of gypsum (as well as its accompanying anhydrite) in sedimentary rocks are in the form of lenses or layers with a thickness of 20-30 meters.

Every year, more than 100 million tons of gypsum are extracted from the bowels of the earth. The world's largest producers of valuable building materials are the USA, Iran, Canada, Turkey and Spain.

In Russia, the main deposits of this rock are concentrated on the western slopes of the Ural Mountains, in the Volga and Kama regions, Tatarstan and the Krasnodar Territory. The main gypsum deposits in the country are: Pavlovskoye, Novomoskovskoye, Skuratovskoye, Baskunchakskoye, Lazinskoye and Bolohovskoye.

Applications of gypsum

The scope of gypsum is extremely wide: construction, medicine, repair and decoration, agriculture, chemical industry.

Since ancient times, sculptures and various interior items have been carved from this mineral - vases, countertops, balustrades, bas-reliefs, etc. Cornices, wall blocks and slabs (the so-called drywall) are often made from it. In its "raw" form, gypsum is also used in agriculture as a fertilizer. It is scattered on fields and lands to normalize the acidity of the soil.

Where else is gypsum used? The mineral is widely used in the paper and chemical industries to produce cement, sulfuric acid, paints and glazes. In addition, anyone who has ever broken a leg or arm is familiar with another area of ​​​​its application - medicine.

Gypsum as a building material

Building material gypsum is obtained from For this, the rock is fired in special furnaces, and then ground into a fine powder. In the future, the resulting raw material is widely used in construction and decoration.

The industrial industry has its own classification of gypsum - technical. So, the following varieties are distinguished:

• high-strength gypsum (used in medicine and dentistry; various building mixtures and molds for the porcelain-faience industry are also produced from it);
• polymeric (used exclusively in traumatology for applying fixing bandages for fractures);
• sculptural (the name speaks for itself - this is the main component of putty mixtures, various figurines and souvenirs);
• acrylic (lightweight gypsum used for finishing the facades of buildings);
• refractory from which plasterboard sheets and wall blocks are often produced).

In addition, there is a separate marking of gypsum for strength. According to it, 12 grades of gypsum are allocated - from G2 to G25.

Alabaster is also widely used in construction and finishing works. Compared to gypsum, it is more durable and easier to work with. True, without special additives, alabaster is practically unsuitable, since it dries out instantly.

It is important to note that even with the modern, such a high level of development of science and industry, a worthy replacement for gypsum has not yet been found.

Healing and magical properties of the stone

Gypsum is not in vain used in medicine. It promotes the fusion of bone tissue, relieves excessive sweating, and cures tuberculosis of the spine. Gypsum is also used in cosmetology - as one of the components of tonic masks.

Since ancient times, this mineral was considered a kind of "cure" for human pride, arrogance and excessive arrogance. In magic, it is believed that gypsum is able to tell a person what he needs to do in a given situation. It promises good luck and material well-being. Astrologers advise people born under the signs of Capricorn, Aries and Leo to wear plaster amulets.

"Desert Rose" - what is it?

Such a beautiful name is called a mineral aggregate, one of the varieties of gypsum. It really does look like flower buds. The aggregates consist of crystalline lenticular intergrowths-petals of a characteristic type. The color of the "desert rose" can be very diverse. It is determined by the color of the soil or sand in which it formed.

The mechanism of formation of these "roses" is rather interesting. They are formed in especially arid natural and climatic conditions. When it occasionally rains in the desert, sand instantly absorbs moisture. Water interacts with particles of gypsum, which are washed away with it deep into. Later, the water evaporates, and the gypsum crystallizes in the sandy mass, creating the most unexpected and bizarre forms.

"Desert Rose" is well known to the nomadic tribes of the African Sahara. Some cultures in the region have a tradition of giving these stone flowers to their loved ones on Valentine's Day.