Oxygen is part of hematite. Blood Ore: Mining, Physical Properties, and Uses of Hematite
Oxygen O has atomic number 8, located in the main subgroup (subgroup a) VI group in the second period. In oxygen atoms, valence electrons are located at the 2nd energy level, which has only s- And p-orbitals. This excludes the possibility of the transition of O atoms to an excited state, therefore oxygen in all compounds exhibits a constant valency equal to II. Having a high electronegativity, oxygen atoms are always negatively charged in compounds (s.o. = -2 or -1). The exception is OF 2 and O 2 F 2 fluorides.
For oxygen, the oxidation states -2, -1, +1, +2 are known
General characteristics of the element
Oxygen is the most abundant element on Earth, accounting for slightly less than half, 49%, of the total mass of the earth's crust. Natural oxygen consists of 3 stable isotopes 16 O, 17 O and 18 O (16 O predominates). Oxygen is part of the atmosphere (20.9% by volume, 23.2% by mass), water and more than 1400 minerals: silica, silicates and aluminosilicates, marbles, basalts, hematite and other minerals and rocks. Oxygen makes up 50-85% of the mass of plant and animal tissues, because it is contained in proteins, fats and carbohydrates that make up living organisms. The role of oxygen for respiration and for oxidation processes is well known.
Oxygen is relatively slightly soluble in water - 5 volumes in 100 volumes of water. However, if all the oxygen dissolved in water passed into the atmosphere, then it would occupy a huge volume - 10 million km 3 (n.c.). This is equal to approximately 1% of all oxygen in the atmosphere. The formation of an oxygen atmosphere on earth is due to the processes of photosynthesis.
Discovered by the Swede K. Scheele (1771 - 1772) and the Englishman J. Priestley (1774). The first used saltpeter heating, the second - mercury oxide (+2). The name was given by A. Lavoisier ("oxygenium" - "giving birth to acids").
In free form, it exists in two allotropic modifications - "ordinary" oxygen O 2 and ozone O 3.
The structure of the ozone molecule
3O 2 \u003d 2O 3 - 285 kJ
Ozone in the stratosphere forms a thin layer that absorbs most of the biologically harmful ultraviolet radiation.
During storage, ozone spontaneously converts to oxygen. Chemically, oxygen O 2 is less active than ozone. The electronegativity of oxygen is 3.5.
Physical properties of oxygen
O 2 - colorless, odorless and tasteless gas, m.p. –218.7 °С, b.p. -182.96 °C, paramagnetic.
Liquid O 2 is blue, solid is blue. O 2 is soluble in water (better than nitrogen and hydrogen).
Obtaining oxygen
1. Industrial method - distillation of liquid air and electrolysis of water:
2H 2 O → 2H 2 + O 2 
2. In the laboratory, oxygen is produced by:
1. Electrolysis of alkaline aqueous solutions or aqueous solutions of oxygen-containing salts (Na 2 SO 4, etc.)
2. Thermal decomposition of potassium permanganate KMnO 4:
2KMnO 4 \u003d K 2 MnO4 + MnO 2 + O 2,
Berthollet salt KClO 3:
2KClO 3 \u003d 2KCl + 3O 2 (MnO 2 catalyst)
Manganese oxide (+4) MnO 2:
4MnO 2 \u003d 2Mn 2 O 3 + O 2 (700 o C),
3MnO 2 \u003d 2Mn 3 O 4 + O 2 (1000 o C),
Barium peroxide BaO 2:
2BaO 2 \u003d 2BaO + O 2
3. Decomposition of hydrogen peroxide:
2H 2 O 2 \u003d H 2 O + O 2 (MnO 2 catalyst)
4. Decomposition of nitrates:
2KNO 3 → 2KNO 2 + O 2
On spaceships and submarines, oxygen is obtained from a mixture of K 2 O 2 and K 2 O 4:
2K 2 O 4 + 2H 2 O \u003d 4KOH + 3O 2
4KOH + 2CO 2 \u003d 2K 2 CO 3 + 2H 2 O
Total:
2K 2 O 4 + 2CO 2 \u003d 2K 2 CO 3 + 3O 2
When K 2 O 2 is used, the overall reaction looks like this:
2K 2 O 2 + 2CO 2 \u003d 2K 2 CO 3 + O 2
If you mix K 2 O 2 and K 2 O 4 in equal molar (i.e. equimolar) amounts, then one mole of O 2 will be released per 1 mole of absorbed CO 2.
Chemical properties of oxygen
Oxygen supports combustion. Burning - b
a rapid process of oxidation of a substance, accompanied by the release a large number warmth and light.
To prove that the flask contains oxygen, and not some other gas, it is necessary to lower a smoldering splinter into the flask. In oxygen, a smoldering splinter flares brightly. The combustion of various substances in air is a redox process in which oxygen is the oxidizing agent. Oxidizing agents are substances that “take away” electrons from reducing substances. The good oxidizing properties of oxygen can be easily explained by the structure of its outer electron shell.
The valence shell of oxygen is located at the 2nd level - relatively close to the nucleus. Therefore, the nucleus strongly attracts electrons to itself. On the valence shell of oxygen 2s 2 2p 4 there are 6 electrons. Consequently, two electrons are missing before the octet, which oxygen seeks to accept from the electron shells of other elements, entering into reactions with them as an oxidizing agent.
Oxygen has the second (after fluorine) electronegativity on the Pauling scale. Therefore, in the vast majority of its compounds with other elements, oxygen has negative degree of oxidation. A stronger oxidizing agent than oxygen is only its neighbor in the period - fluorine. Therefore, compounds of oxygen with fluorine are the only ones where oxygen has a positive oxidation state.
So, oxygen is the second most powerful oxidizing agent among all the elements of the Periodic Table. Most of its most important chemical properties are related to this.
All elements react with oxygen, except for Au, Pt, He, Ne and Ar; in all reactions (except for interaction with fluorine), oxygen is an oxidizing agent.
Oxygen easily reacts with alkali and alkaline earth metals:
4Li + O 2 → 2Li 2 O,
2K + O 2 → K 2 O 2,
2Ca + O 2 → 2CaO,
2Na + O 2 → Na 2 O 2,
2K + 2O 2 → K 2 O 4
Fine iron powder (the so-called pyrophoric iron) spontaneously ignites in air, forming Fe 2 O 3, and steel wire burns in oxygen if it is heated in advance:
3 Fe + 2O 2 → Fe 3 O 4
2Mg + O 2 → 2MgO
2Cu + O 2 → 2CuO
With non-metals (sulfur, graphite, hydrogen, phosphorus, etc.), oxygen reacts when heated:
S + O 2 → SO 2,
C + O 2 → CO 2,
2H 2 + O 2 → H 2 O,
4P + 5O 2 → 2P 2 O 5,
Si + O 2 → SiO 2, etc.
Almost all reactions involving oxygen O 2 are exothermic, with rare exceptions, for example:
N 2 + O 2 → 2NO-Q
This reaction takes place at a temperature above 1200 o C or in an electrical discharge.
Oxygen is able to oxidize complex substances, for example:
2H 2 S + 3O 2 → 2SO 2 + 2H 2 O (excess oxygen),
2H 2 S + O 2 → 2S + 2H 2 O (lack of oxygen),
4NH 3 + 3O 2 → 2N 2 + 6H 2 O (without catalyst),
4NH 3 + 5O 2 → 4NO + 6H 2 O (in the presence of a Pt catalyst),
CH 4 (methane) + 2O 2 → CO 2 + 2H 2 O,
4FeS 2 (pyrite) + 11O 2 → 2Fe 2 O 3 + 8SO 2.
Compounds containing the dioxygenyl cation O 2 + are known, for example, O 2 + - (the successful synthesis of this compound prompted N. Bartlett to try to obtain compounds of inert gases).
Ozone
Ozone is chemically more active than oxygen O 2 . So, ozone oxidizes iodide - ions I - in a solution of Kl:
O 3 + 2Kl + H 2 O \u003d I 2 + O 2 + 2KOH
Ozone is highly toxic, its toxic properties are stronger than, for example, hydrogen sulfide. However, in nature, ozone, contained in the high layers of the atmosphere, acts as a protector of all life on Earth from the harmful ultraviolet radiation of the sun. The thin ozone layer absorbs this radiation, and it does not reach the Earth's surface. There are significant fluctuations in the thickness and length of this layer over time (the so-called ozone holes), the reasons for such fluctuations have not yet been clarified.
Application of oxygen O 2: to intensify the processes of producing iron and steel, in the smelting of non-ferrous metals, as an oxidizer in various chemical industries, for life support on submarines, as an oxidizer for rocket fuel (liquid oxygen), in medicine, in welding and cutting metals.
The use of ozone O 3: for disinfection of drinking water, sewage, air, for bleaching fabrics. 
Fe 2 O 3 (a-Fe 2 O 3)
Greek, “gematos” - blood (the mineral supposedly stops the blood) Synonyms: iron shine, speck-lyarite, iron mica, red iron ore
Chemical composition. Iron (Fe) 70%, oxygen (O) 30%; there is an admixture of titanium in titanohematite; in insignificant quantities, water (hydrohematite) may also be included in the chemical composition.
Color. Coarse-crystalline varieties are iron-black to steel-gray, and dense varieties (red glass head) are steel-gray to bright red.
Shine. Metallic, semi-metallic, rarely dull, earthy.
Transparency. In thin plates translucent dark red.
Damn. Cherry-red, brown-red. Hardness. 6,5.
Density.|,9-5,3.
Break. Exfoliates into scales.
Syngony. Trigopal.
The shape of the crystals. Often lamellar, rhombohedral and tabular crystals.
Crystallographic structure. Similar to the structure of corundum.
Symmetry class. Ditrigonal-scalenohedral.
Axis ratio, c/a = 1.366.
Cleavage. Absent.
Aggregates. Leafy, granular, scaly, dense, cryptocrystalline, sinter, kidney-shaped (red glass head), earthy (hydrohematite), oolitic (caviar stone, pea | ore - iron oolites). P. tr. Doesn't melt.
behavior in acids. Slowly decomposes into HC1.
Associated minerals. Quartz, pyrite, magnetite, martite, carbonates, chlorite.
similar minerals. Ilmenite, magnetite, chromites, franklinite, cinnabar.
Practical value. Hematite ores are the most important ores of iron, the world reserves of which amount to billions of tons.
Origin. Varieties of hematite are formed in various conditions: 1) pneumatolytic way - scaly iron luster, often found in tin deposits; 2) as a product of volcanic sublimations in volcanic craters and in lavas - in the form of tabular segregations; 3) pneumatolytic-hydrothermal or contact-metasomatic way - in the form of drusen or dense masses; 4) hydrothermal way - in the form of druses; 5) during marine eruptions - in the form of dense solid masses of red iron ore; 6) Regional metamorphism leads to the formation of hematite quartzites, magnetite-hematite quartzites, and hematite schists.
Place of Birth. Slbingerode, Braunesumpf and other deposits in the Harz, Schleize and other deposits in the Thuringian Forest, numerous deposits of the Ore Mountains, earthy ores composed of red iron ore (complex ores), also containing nickel and chromium minerals near Hohenstein-Ernsttal, Waldheim, Böhrigen, and others deposits in the Saxon Granulite Mountains (GDR). The world-famous deposits of Elbe; hematite-magnetite ores of Krivoy Rog, Kursk magnetic anomaly, etc. (USSR); lake Upper (USA, Canada); hematite schists (itabirites) in pieces. Minas Gerais (Brazil); large deposits located in various parts of Africa, and other deposits in various parts of the world.
Ores. In the chemical formula of the mineral, ferrum is supplemented with oxygen. The oxide is reddish, in powder it resembles gore. It becomes scarlet when dissolved in water. By creating a single mass, the particles look.
Composition of hematite can be supplemented with impurities of oxides and. Sometimes, water is also included in the mineral. It happens up to 8%. Oxide may account for 14%. The proportion of the duet of titanium with oxygen does not exceed 11%.
Hematite is a mineral. Under this concept, geologists mean crystalline bodies. They are homogeneous, exist separately, or are part of the rocks.
So, hematite is an impurity to many, coloring them in. Scarlet shades of iron ore are also due to some, and.
Hematite properties
Properties minerals are determined by their composition and structure. The abundance of iron gives metallic. Rare, found hematite. Stone it happens not only, but also brown, as well as bright.
The color is due to the concentration of iron oxide and the amount of foreign impurities. Water, for example, significantly dilutes the colors, reducing them instead to a scarlet spectrum.
Red hematite more common in cryptocrystalline masses. They can be slick, reminiscent of metal bubbles. Geologists call such spherical shapes concretions.
Part of the ore is layered, and part is presented. The latter, often, and dark. By the way, hematite crystals have a separate name - specularite.
On photo hematite in crystals it resembles tablets, or wide plates. Stone aggregates are called so, lamellar and tabular. There are also rhombohedral crystals. But, they are only 5-10%. By rhombohedral is meant aggregates in the form of three-dimensional rhombuses. They have 6 edges.
Its strength depends on the state of aggregation of the hero of the article. Brittle in crystals. Pieces easily break off from the mineral, and cracks form upon impact. In cryptocrystalline masses, hematite is stronger.
It, on the contrary, is more in crystals, it reaches 6.5 points. In concretions, it differs only by 5.5-6 points. The indicators are taken from . It has 10 divisions.
On each of them is a mineral marker with exactly 1 point, 2.3, and so on. If a 6-point stone leaves scratches on hematite, and iron ore, in turn, follows a 5-point stone, then it itself pulls about 5.5.
If we take the average value of hematite, and this is 6 points, the gem can be compared with a ruby. That is, the hero of the article is suitable for jewelry, but is not a champion of hardness. There are 4 more points to the diamond. This means that hematite products should be stored carefully, avoiding contact with harder and more durable stones and metals.
Due to the presence of iron, hematite is heavy. The density of the mineral is 2 points higher than the average gem. Instead of 3 grams per cubic centimeter, the mass of iron ore is almost 6.
Resembling outwardly, hematite is devoid of transparency. Only brown and scarlet crystals are slightly translucent. Both they and the cryptocrystalline masses of the mineral lack cleavage. This means that the gem does not have certain axes along which it tends to split. If damage occurs, it is chaotic.
Deposits and mining of hematite
Hematite widespread. This is due to the ability of the stone to form, both at depths and on the surface of the earth's crust. Geologists call the first way of formation endogenous, and the second - exogenous.
At depths, hematite is included in the composition of granitoids, syenites, and. In them, the hero of the article appears on late stage crystallization of rocks from hot magma.
On the surface of the planet, iron ore becomes part of the effusive masses. They are also called outcasts. Effusive rocks are formed when lava flows over the surface of the earth. Gases are released from the mineral mass. At this point, specularite appears. This is the name of the mica-like form of hematite.
Iron ore is also found in places of contact metamorphism, where already formed rocks are affected by pressure and temperature. This is how glandular, and are formed.
Finding the hero of the article is obtained even in sedimentary masses, for example, an oolite. There, hematite occurs in the form of lenses. In the case of metamorphic deposits, the mineral, as a rule, fills the cracks in the rocks. At the depths lies in solid masses.
Application of hematite
Being a ferrum oxide, hematite serves as iron ore. Next, it is worth talking about the use of metal. So, iron is needed for smelting and. Ferrum is also included in some s.
crushed buy hematite manufacturers of paints and pencils seek. In both cases, the hero of the article serves as a dye, giving scarlet and brown tones. Interestingly, some of the rock carvings, which, according to scientists, are 30,000-35,000 years old, were made with hematite powder. It turns out that articles were used as a coloring hero at the turn of the Ice Age.
Pictured is a pendant with hematite inserts
Iron ore is also used in practice. They work mainly with solid masses of the mineral. They are easier to process. The lack of transparency and brittleness of hematite imply a cut in the form of .
Of these, they make up. Can be found pegmatite bracelet. A gem is also inserted into the rings, as in. Sometimes, the mineral is not processed. Thus, lamellar ore crystals grow on top of each other, decreasing in size towards the center. It turns out splices similar to buds. This is how they are inserted into the . Usually this hematite in silver and base alloys.
Not without iron oxide souvenirs. They expose candlesticks and eggs on stands, and without them. Given the density of hematite, the goods are heavy. Is it hard a rounded stone is valued at 100-500 rubles, depending on the presence of metal framing and its quantity.
Pictured is a silver ring with hematite
Hematite rings offer for 200-400 rubles. This is the price tag for a solid ring, without metal additions. effective, but are in demand not only because of aesthetics. People are also drawn to the magical, healing properties of the mineral.
Magic and medicinal properties hematite
magical properties hematite closely related to medicine. Since the stone affects the circulatory system, it means that it is able to endow with the qualities characteristic of people in whose veins the blood, as they say, boils.
The gem awakens courage, makes courageous. Therefore, to the question who is suitable for hematite, used to answer: - "Men." However, in modern world the boundaries between the sexes are erased. Masculinity will not interfere with female rescuers, firefighters, and the military.
Medicinal properties of hematite not only accelerate blood flow, but also clear the places of blockage of blood vessels. Otherwise, it would not be possible to increase blood circulation. Even Theoflast wrote that iron ore protects against anemia.
The Greek philosopher also wrote about the effect of hematite on reproductive function, the functioning of the kidneys and liver. True, the hero of the article helps the last organs only when the cause of the disease is associated with insufficient blood circulation.
Hematite Jewelry
If purchased with hematite not only for the sake of shine, but also for magic, they are recommended in a copper frame. If hopes are pinned on medicinal properties, models with an abundance of iron ore are needed.
The mineral has a weak magnetism. It has a tonic effect, improves immunity. Since magnetism is weak, for the proper effect, beads are needed in several rows, or several, worn at the same time.
The name of the mineral hematite comes from the Greek "ema" - blood, "ematites" - a bloody stone (Theophrastus, 325 BC). English name for the mineral Hematite
Synonyms: Olyzhist- oligiste - the name used in France; anhydroferrite - anhydroferrite (according to Chester, 1896). Martit- martite (Breithaupt, 1828) - hematite pseudomorph after magnetite.
Rutilohematite - rutilohematite and ilmenohematite - ilmeno-liematite - hematite with microinclusions of rutile, respectively, ilmenite.
Sinter formations O 3
Krovavik red-banded quartzites.
Chemical composition
The theoretical chemical composition: Fe 2 O 3 - 100 (Fe - 69.94). It often contains a certain amount of Ti, partly due to ilmenite inclusions, partly in solid solution; also contains a certain amount of Al and Mn in solid solution (up to 17% Mn in homogeneous hematites from the Ardennes); sometimes contains Ca, Mg, Fe 2+ (up to 5% FeO at 10% TiO 2 in "basanomelan"). In cryptocrystalline dense masses, SiO 2 and Al 2 O 3 in the form of mechanical impurities, in fibrous and earthy varieties - H 2 O (hydrohematite).
In the mineral from different deposits, impurities of Cr, Ni, Co, also V (up to 0.03% in the Dastakert deposit of Armenia, up to 4-10-3% from the deposit of Mongolia), In (in hydrohematite from Sarybulak, Kyrgyzstan, up to 0, 41%), Sn, Zn, etc.
Varieties
A) According to the features of the composition.
Titanohematite - titanohematite (Eduarde, 1938) contains up to 11.3% TiO 2 in solid solution. Met at Mount Monger Western Australia. The streak is dark brown to black. Less rich in titanium (5% TiO 2 ) was observed in the Swiss Alps and in the Fitzroy sands, New Zealand(MgO - 1.5; FeO - 5.8; Fe 2 O 3 - 83.1; TiO 2 - 9.6). At 700-900° the miscibility of Fe 3 O 3 and FeTiO 3 is complete, limited at room temperature; For the most part, the content of TiO 2 in hematites is due to the decomposition of the solid solution.
Alumohematite - alumohematite (Beneslavsky, 1957) - contains up to 14% Al 2 O 3 in solid solution.
A mineral with a content of up to 11-14% Al 2 O 3 was artificially obtained, which indicates the possibility of the formation of Al-containing hematites in sedimentary rocks rich in alumina.
Hydrohematite - hydrohematite (Breithaupt, 1847) - fine crystalline hematite, containing up to 8% water. The radiograph corresponds to that of hematite. Collomorphic textures are often observed under the microscope. The density is lower than that of hematite itself: 4.40 - 4.80; reflectivity is lower, internal reflections are less dense. Usually formed during hypergene processes. It was noted in the composition of sedimentary iron ores of the Alapaevsk type (Sverdlovsk region), in the composition of iron ores of the Belozersky deposit (Ukraine), widely distributed in the zone of oxidation of deposits of the steppe part of Kazakhstan, etc.
Thin mixtures of hydrohematite or hematite with hydrogoethite (limonite) are known as turites.
B) According to the structure and form of secretions.
iron shine- Eisenglanz (Agricola, 1546) - clear crystal segregations of the mineral, mostly black with a metallic sheen, often in the form of crystals.
Synonyms: Specularite - specularite (Dana, 1892), specular hematite, specular iron, shiny iron ore - Glanzeisenerz (Breithaupt, 1816), shiny iron ore - Glanzeisenstein (Hoffman, 1816); mirror ore - Spiegelerz (Valerius, 1747).
Some highlights of the iron sheen are known by special names. Iron rose - Eisenrose (partially basanomelan - Basanomelan, Kobel, 1838) - an aggregate of lamellar crystals that have grown together almost parallel along the basopinacoid; resembles a double flower; fine examples come from Saint Gotthard in Italy. Iron mica - Eisenglimmer (Valerius, 1747) - thin-scaly discharges of iron luster. Iron sour cream - Eisenrahm (Werner, 1789) - loose easily soiled aggregates of very small flakes iron mica red, greasy to the touch. Precambrian (?) shale rocks of Brazil, containing a significant amount of iron mica, are known under the names of itabirite - itabirite (Eshwege, 1822) and Yakutings - jacutinga; according to the suggestion of Derby (1910), hematite-quartz schists of other regions are also called itabirites the globe. Crystalline individuals of this mineral in shales can show a certain orientation.
Hematite- Botheisenstein (Werner, 1817) - fine-crystalline or cryptocrystalline segregations of hematite, usually red.
Synonym: blood stone-Blutstein (Agricola, 1546), bloodstone. Red glass head-rother Glaskopf, kidney-shaped (kidney) ore-kidney ore - sinter aggregates with a radially radiant and often with a concentric shell-like structure. Oolitic red iron ore - red oolitic hematite - consists of oolites. Ocher red ironstone - red ocher hematite, red ocher - ochra rubra (Valerius, 1747), rötel - Rothel (Leonhard, 1821), red earth - reddle, red chalk - red chalk, red pencil (according to Shubnikova, 1937), sangin - sanguine - earthy aggregates, sometimes mixed with clay minerals. Hematogelite - hematogelite (Tuchan, 1913), hematitegelite - hematitogelite - the coloring matter of red bauxites. Vapa is a mineral with an admixture of clay.
Martit- pseudomorphosis (false form) on black magnetite. Crystals in the form of octahedrons.
An oriented mutual intergrowth of hematite and ilmenite (“Washingtonite”) is observed - the result of the decomposition of solid solutions: ilmenite plates are parallel (0001) or (1011); oriented plates of hematite in ilmenite are also noted, oriented parallel to (0001) ilmenite; there are parallel intergrowths of hematite and ilmenite crystals after (0001). Hematite crystals sometimes naturally grow in a (0001) plane on the faces of a magnetite or spinel octahedron; its oriented intergrowths with magnetite are observed under a microscope among the decomposition products of solid solutions: (111) and magnetite in parallel (0001) and .
Rutile forms oriented growths on hematite: (100) and (101) rutile parallel to (0001) and (1010) hematite. An oriented growth of pseudobrookite crystals on hematite crystals was also observed: (121) and pseudobrookite in parallel (0001) and hematite; when replacing wolframite: (0001) and hematite in parallel (100) and wolframite. Regular intergrowths of hematite with quartz are described: (1010) and quartz in parallel (0001) and hematite.
Regular ingrowths of it in muscovite were noted with the location of hematite inclusions on (001) mica in three directions at an angle of 60 ° and the formation of a lattice, which causes the phenomenon of asterism in mica. Acicular inclusions of hematite are known in corundum with mutually parallel axes of both minerals. Regularly arranged flakes of hematite are found in carnallite: (0001) and hematite parallel to (001) and or carnallite; also parallel to (130) and carnallite; in sylvite: (0001) hematite parallel to (100), (111) or less commonly parallel to (110) sylvite; in cancrinite: (0001) hematite parallel to (1010) or (1120) cancrinite; in feldspar - (0001) hematite is parallel to a number of feldspar faces; in calcite (siderite) with hematite ingrowths, the (1120) faces of both minerals are sometimes parallel.
Crystallographic characteristic
- Syngony. Trigonal. L 3 3L 2 3RS
- Class. Ditrigonal scalenohedral. D3d - 3m
Crystal structure
The structure is similar to that of corundum.
Major forms: The most common forms are r, c and n, also e and a.
Form of being in nature
Crystal Shape diverse: rhombohedral, tabular - mainly in crystals formed from hydrothermal and gas solutions; isometrically developed crystals are observed (mainly in contact-metasomatic deposits); rare prismatic crystals.
On (0001) - hatching in three directions, parallel to the edges (0001): (1011), triangular depressions, also triangular growth pyramids, signs of spiral growth, natural etching, etc.
Doubles
Intergrowth and intergrowth twins according to (0001) with an intergrowth plane (1010) ; twins along (1011) with an angle between basopinacoids equal to 64°48 are very common; in this case, often small crystals, when growing in a twin position onto a larger tabular crystal, are arranged differently - at an angle of 120 ° to each other. Twinning may be due to the pressure experienced by the crystals. Sliding along T (0001), t .
Intergrowths of thin-plate crystals are characteristic (individual plates grow with faces with (0001) almost parallel to each other), composing the so-called iron roses, which may be the result of the spiral growth of crystals.
An oriented mutual intergrowth of it and ilmenite (“Washingtonites”) is observed - the result of the decomposition of solid solutions: ilmenite plates are located parallel (0001) or (1011); oriented blades are also noted in ilmenite, oriented parallel to (0001) ilmenite; there are parallel intergrowths of hematite and ilmenite crystals after (0001). Hematite crystals sometimes naturally grow in a (0001) plane on the faces of a magnetite or spinel octahedron; its oriented intergrowths with magnetite are observed under a microscope among the decay products of solid solutions: (111) and magnetite in parallel (0001) and hematite.
Rutile forms oriented growths on hematite: (100) and (101) rutile parallel to (0001) and (1010) hematite. An oriented growth of pseudobrookite crystals on hematite crystals was also observed: (121) and pseudobrookite in parallel (0001) and hematite; when replacing wolframite: (0001) and hematite in parallel (100) and wolframite. Its regular intergrowths with quartz are described: (1010) and quartz in parallel (0001) and .
Regular ingrowths of hematite in muscovite were noted with the location of hematite inclusions on (001) mica in three directions at an angle of 60° and the formation of a lattice, which causes the phenomenon of asterism in mica. Acicular inclusions of hematite are known in corundum with mutually parallel axes of both minerals. Regularly arranged flakes of hematite are found in carnallite: (0001) and hematite parallel to (001) and or carnallite; also parallel to (130) and carnallite; in sylvite: (0001) hematite parallel to (100), (111) or less often papally (110) sylvin; in cancrinite: (0001) hematite parallel to (1010) or (1120) cancrinite; in feldspar - (0001) hematite is parallel to a number of feldspar faces; in calcite (siderite) with hematite ingrowths, the (1120) faces of both minerals are sometimes parallel.
Growths in quartz, microcline, acid plagioclase and potassium feldspar give these minerals a beautiful sparkling golden tint (aventurine, sun stone).
Inclusions of the smallest plates of the mineral color some minerals in red (carnallite, sylvin, heulandite, cancrinite, etc.).
Aggregates. It usually occurs in the form of dense, finely crystalline, scaly, or leafy accumulations, as well as in earthy masses and sinter aggregates. In the latter case, it is called red iron ore. Sometimes concentric-layered and radially radiant, sinter, reniform and oolitic.
Leaks. mineralogical plummet Physical properties
Optical
- The color of the clear crystalline varieties is steel gray to black; sometimes there is fading. Cryptocrystalline - dull red to bright red, cherry red to black. In the unfiltered rays of a mercury-quartz lamp, it is yellowish-white (in contrast to the bluish-white ilmenite).
- The trait is cherry-red or reddish-brown, red (a characteristic diagnostic sign). .
- Shine metallic to semi-metallic
- Low tide matte
- Transparency In thin fragments translucent blood red.
Mechanical
- Hardness 5-6. The data of different authors on microhardness fluctuate over a wide range.
- Brittle in crystals, elastic in thin plates.
- Density 5.26.
- There is no cleavage, separation along (0001) and (1011) is due to twinning.
- The fracture is semi-conchoidal to uneven.
Chemical properties
In an acidic aqueous solution at temperatures of 100-160°, hematite dissolves with decomposition; concentration of Fe 3+ in solutions at 100° (in mg/l): 0.37 at pH about 2; 0.04 at pH = 4; 0.01 at pH= 6.11; respectively at 160°: 0.14; 0.04; 0.01; at temperatures of the order of 350 ° and pH = 5-7, the dissolution of the mineral proceeds without decomposition. Soluble in concentrated HCl. It is not etched in polished sections by any of the standard reagents. For structural etching, concentrated HF is used (etching duration 1–2 min).
Other properties
Conductor of electricity. Data on the electrical resistivity of natural samples fluctuate over a wide range; at increased voltage, it has detector properties.
At room temperature it is antiferromagnetic, at -15° it becomes ferromagnetic. Characterized by high stability in relation to constant and variable magnetic fields, as well as to temperature effects.
It is successfully floated by anionic collectors such as oleic acid or alkyl sulfates (optimum conditions are neutral or slightly alkaline medium). Infusible. In a restorative flame it becomes magnetic.
Melting point 1594°. When heated to 1370-1400°, it transforms into magnetite. γ-Fe 2 O 3 , which is formed when heated to 950°, turns into α-Fe 2 O 3 when cooled.
Artificial production of hematite
Hematite is obtained by sublimation by the interaction of ferric chloride and water vapor; when heating the melt of borax with iron oxide; from silicate melt with a high content of iron; when iron oxide hydrate is heated with water in a sealed tube, etc. Obtained in the study of many systems: hematite - ilmenite, corundum - magnetite, etc.
Diagnostic features
It is easily distinguished from magnetite and ilmenite by the color of the line; unlike maghemite, it is optically anisotropic and not magnetic. Dense hematite differs from cinnabar in the absence of cleavage, optical sign, and also in hardness and density. In fine-grained aggregates, it is difficult to distinguish from lepidocrocite. In polished sections, it is much lighter than magnetite, ilmenite, and other accompanying ore minerals.
Satellites. Corundum, diaspore, rutile, andalusite, quartz, musketite. Mushketovite is known in contact-metasomatic deposits (Urals, Tajikistan, etc.) and in hydrothermal deposits, which are characterized by the deposition of sulfides after hematite (Kutimskoe deposit in the Perm region, etc.); Maghemite can form along with magnetite after hematite. During diagenesis, in the presence of reducing agents ( organic matter) can pass into siderite, pyrite and leptochlorites (in the CIS - rocks of the Donbass, the Second Baku and the Erunakovskaya strata of Kuzbass). In addition to magnetite, pseudomorphs after hematite are observed: pyrite, siderite, chlorites, hydrogoethite (limonite), in some cases - chalcopyrite, rutile, cassiterite, manganite, etc.
Practical use
Mineral of many iron ores. Pure powdered differences are used as red paints and for the preparation of red pencils. Dense stone ("bloodstone") is used as a polishing material.
Red-banded jasper-shaped hematite-magnegit hornfelses of Krivoy Rog are an effective decorative and ornamental stone, the carmine shades of which complement the rich palette of domestic gemstones.
Physical research methods
Differential thermal analysis
ancient methods. Under the blowpipe
Crystal optical properties in thin preparations (sections)
In thin sections in transmitted light, blood-red (in the thinnest plates), orange-red, gray-yellow. Weak pleochroism: brownish-red according to No; according to Ne yellowish-red. Single axis (-). Light refraction is high, birefringence is very strong.
Mineral photo gallery
domain process is the smelting of pig iron from iron ores in blast furnaces.
To implement the domain process, you need to have in the required quantities:
refractory materials.
prepared for melting iron ore,
Ore
Ore is a rock containing metal; usually the ore contains metals in an amount that allows cost-effective extract metal from ore.
Iron ores are mainly iron oxides, connected to waste rock.
Waste rock called a natural mineral compound that does not contain iron, for example silica(SiO2), alumina(Al 2 O 3), etc.
For domain process ores are used, in which the iron content exceeds 25-30%.
Depending on the chemical composition iron ores are divided into the following groups:
Magnetic iron ore
Magnetic iron ore(magnetite), which is a magnetic iron oxide Fe 3 O 1 . IN pure form magnetite contains 72.4% iron And 27.6% oxygen and has magnetic properties.
The most powerful deposit magnetic iron ore is Magnitogorsk field , in which the iron content reaches 62%.
In 1940, the extraction of Magnitogorsk ore accounted for 22.5% of the total ore production in the USSR.
Hematite
Hematite (hematite)- anhydrous iron oxide (Fe 2 O 3). In its chemically pure form, hematite contains 70% iron And 30% oxygen.
The largest deposit of red iron ore in the USSR (hematite) is Krivoy Rog field . Ores containing 40-60% iron are sent for remelting.
brown iron ore
brown iron ore (limonite)- aqueous iron oxide (2Fe 2 O 3 * H 2 O). In its purest form limonite contains 59.88% iron And 14.43% water of hydration.
The largest deposit of brown iron ore is Kerch field , the iron content of which is 32.36%.
The ores of this deposit are also distinguished by a high content of phosphorus (from 0.4 to 1.3%) and the presence of arsenic from 0.05 to 0.2%.
Spar iron ore
Spar iron ore (siderites) FeCO3. In its pure form, siderite contains 48.3% iron And 37.9% CO 2 .
Large deposit spar iron ore is located in the South Urals near the Bakalskoye deposit brown iron ore.
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