What are the 8 mineral groups and examples?

1.3. Classification of minerals by chemical composition. Study and description of minerals of the main classes from the educational collection Task 1. Based on the educational collection, study and describe the basic properties of minerals of the following classes: 1) native elements, 2) sulfides, 3) halides, 4) oxides and hydroxides, 5) carbonates, 6) sulfates, 7) phosphates, 8) tungstates , and 9) silicates and aluminosilicates. Task 2. Using the example of minerals of the class of silicates and aluminosilicates, trace the dependence of the external appearance of minerals on the structure of the crystal lattice. Note. This topic is studied over four lessons. Theoretical part Currently, more than 2500 natural minerals are known, not counting varieties, but only a few of them (about 50) are important in the formation of rocks that make up the earth’s crust. They’re called rock-forming. The remaining minerals in rocks are found in the form of minor impurities and are called accessory minerals or simply accessories (Latin “accessorius” – additional). Modern classification of minerals is based on their chemical composition and crystal structure. The main rock-forming and ore minerals, the study of which is included in the course program, are combined into several classes. 1.Native elements . This class includes minerals consisting of a single element. About 45 minerals of this class are known, constituting 0,01% of the mass of the earth’s crust. It includes: native gold Au, silver Ag, copper Cu, platinum Pt, graphite C, diamond C, sulfur S, etc. 2.Sulfides – compounds of various elements with sulfur. They also have little importance in the structure of the earth’s crust, but include a number of minerals – the most important ores for lead, copper, zinc, molybdenum, etc. These include: pyrite (sulfur pyrite) FeS ₂ , chalcopyrite (copper pyrite) CuFeS ₂ , bornite Cu ₅ fez ₄ , galena (lead luster) PbS, sphalerite (zinc blende) ZnS, molybdenite (molybdenum luster) MoS ₂ , cinnabar HgS, etc. 3.Halide compounds . Minerals of this class are chemically salts of hydrohalic acids. The most common are chloride and fluoride compounds. These include halite (table salt) NaCl, sylvite KCl, fluorite (fluorspar) CaF ₂ . 4.Oxides and hydroxides . This class includes minerals – compounds of various elements with oxygen and a hydroxyl group. It occupies one of the first places in terms of the number of minerals it contains; it accounts for about 17% of the mass of the earth’s crust. Minerals of this class are divided into two groups: 1) oxides and hydroxides of silicon (quartz group) SiO ₂ and 2) metal oxides and hydroxides. Quartz is one of the most common minerals in the earth’s crust, making up about 12% of it by weight and is part of almost all genetic types of rocks. Varieties of quartz include: transparent rock crystal, purple amethyst, smoky rauchtopaz, black morion and some other minerals. The cryptocrystalline variety of quartz is the mineral chalcedony; banded variety of chalcedony – agate; chalcedony contaminated with impurities – flint. Silicon hydroxide is represented by a mineral called opal SiO ₂ nH ₂ O. The class of metal oxides and hydroxides includes a number of the most important ore minerals: magnetite (magnetic iron ore) FeO Fe ₂ O ₃ , hematite (iron luster or red iron ore) Fe ₂ O ₃ , corundum Al ₂ O ₃ , chromite FeCr ₂ O ₄ ; from hydroxides – limonite (brown iron ore) Fe ₂ O ₃ nH ₂ O, aluminum hydroxides – gibbside minerals Al (OH)₃ and AlO (OH) diaspores that are part of bauxite (aluminum ore). 5. Carbonate – carbonic acid salts (H ₂ CO ₃ ). The carbonate class includes minerals: calcite (lime spar) CaCO ₃ , a transparent variety of which is called Iceland spar, dolomite CaMg (CO ₃ )₂, siderite FeCO ₃ , magnesite MgCO ₃ . Aqueous carbonates include the beautiful ornamental mineral malachite Cu ₂ CO ₃ (OH)_2. 6. Sulfate – salts of sulfuric acid (H ₂ SO ₄ ). These include gypsum C and SO ₄ ·2 H ₂ O, anhydrite (anhydrous calcium sulfate) CaSO ₄ , barite BaSO ₄ and more 7. Phosphate – salts of orthophosphoric acid (H ₃ PO ₄ ). The most common minerals among phosphates are apatite C a ₅ [P.O. ₄ ]₃(F, OH, Cl) and a cryptocrystalline difference of the same composition – phosphorite. Widely used for the production of fertilizers and in the chemical industry. 8. Tungstates – salts of tungstic acid (H ₂ WO ₄ ). These include the minerals wolframite (Fe, Mn) WO ₄ and scheelite CaWO ₄ , which are tungsten ore. 9.Silicates – salts of hypothetical silicic acid (one of the acid formulas H ₄ SiO ₄ ). This class includes the most common rock-forming minerals in the earth’s crust, which are extremely complex in chemical composition and participate in the structure of all types of rocks, especially igneous and metamorphic. They make up approximately one third of all known minerals. According to N.V. Belov, silicates, including quartz, which also belongs to silicates in structure, make up more than 90% of the entire earth’s crust by weight. A harmonious classification of this complex class of minerals became possible only thanks to crystal chemical studies, which established a close connection between their structure and chemical composition. The crystal lattice of all silicates is based on the ionic tetravalent group [SiO ₄ ] 4- , forming tetrahedrons, different combinations of which determine the structure of silicates (Fig. 11). Rice. 11. Structure of silicon-oxygen tetrahedron All silicates according to their internal structure are divided into: 1) island, the structure of which consists of isolated tetrahedra (for example, minerals of the olivine group); 2) ring, the silicon-oxygen tetrahedra, connecting with each other, form closed rings (for example, the mineral beryl); 3) chain – those silicates in which tetrahedra are connected into continuous chains (for example, a group of pyroxenes); 4) tape – in them, chains of tetrahedrons, connecting with each other, form isolated ribbons or stripes (for example, a group of amphiboles); 5) layered or leaf silicates combine many minerals, the structure of which is determined by the adhesion of ribbons in the form of one continuous layer (for example, minerals of the mica group, clay minerals, serpentinite); 6) wireframe silicates in which silicon-oxygen tetrahedra are linked through all four vertices, creating a framework (Fig. 12). Fig. 12. Structure of silicates: a) ring; b) chain, c) tape; d) layered, or sheet; d) frame. Framework silicates include, in particular, a very important group of rock-forming minerals – feldspars. Minerals of the feldspar group are widespread in the earth’s crust, making up about 50% of it, and are rock-forming minerals of many igneous and metamorphic rocks. According to their chemical composition, feldspars are divided into two subgroups: 1) potassium-sodium feldspars, which make up the subgroup of orthoclase, which includes orthoclase itself, microcline, its green variety – amazonite, etc. and 2) lime-sodium, or sodium-calcium, feldspars, or plagioclases. Plagioclases represent a continuous series of isomorphic minerals from albite to anorthite: albite, oligoclase, andesine, labradorite, bytownite, anorthite. The extreme members of this series are the sodium plagioclase albite Na[AlSi ₃ O ₈ ] and calcium plagioclase anorthite Ca [Al ₂ Si ₂ O ₈ ]. All intermediate minerals of this series are a mixture of albite and anorthite molecules in various proportions. In accordance with this, plagioclases are divided into acidic (albite, oligoclase), intermediate (andesine, labradorite) and basic (bytownite and anorthite). In alkaline igneous rocks, minerals of the feldspathoid group are developed, consisting of the same chemical elements as feldspars, but with a lower content of silicon oxide. Among them, the most common mineral is nepheline. The internal structure of silicates and aluminosilicates largely determines their properties: minerals with an island structure, characterized by dense packing of ions, often form isometric crystals, have high hardness, density and imperfect cleavage. Minerals with linearly elongated structures (chain and ribbon) form prismatic crystals with well-defined cleavage in two directions along the long axis of the structure. Minerals with a layered structure form tabular crystals with very perfect cleavage, parallel to the “layers” of the structure. Both in the feldspars described above (albite-anorthite series) and in many other silicates, the phenomena isomorphism (Greek “izos” – equal, “morphe” – form), which means the property of elements to replace each other in chemical compounds of related composition and form a series of mixed minerals of the same crystalline form. Guidelines This work is completed over four lessons. Using the description of minerals in this manual (see below), as well as other reference materials and keys available in the geology classroom, students study minerals from the educational collection, describing them in a workbook according to the following plan: 1. Name of the class of minerals. 2. Name and chemical formula of the mineral. 3. Its main physical properties. 4. Distinctive features. In the first lesson, students study minerals of the first three classes: native elements (sulfur, graphite, shungite); sulfides (pyrite, chalcopyrite, pyrrhotite, galena, sphalerite, cinnabar, molybdenite, stibnite, orpiment); halides (halite, or table salt, fluorite). In the second lesson, students study the minerals of the class oxides и hydroxides. This class is divided into two groups: a) oxides и hydroxides silicon – this is quartz and its varieties: rock crystal, amethyst, morion, rauch-topaz, chalcedony, carnelian, agate, flint; and b) oxides и hydroxides metals (hematite, limonite, magnetite, martite, titanomagnetite, chromite, cassiterite, pyrolusite, psilomelane). The third lesson is devoted to the study of minerals of the following classes: carbonates (calcite, Iceland spar, marble onyx, dolomite, magnesite, siderite and hydrous copper carbonate malachite); sulfates (gypsum, gypsum-selenite, barite, celestine, jarosite, alunite); and phosphates (apatite, phosphorite); tungstates (scheelite, wolframite). In the fourth lesson, students study minerals of the class silicates и aluminosilicates, which are divided into: a) island (minerals of the olivine group, in particular forsterite; minerals of the garnet group: almandine, uvarovite, andradite; disthene, sphene); b) ring (beryl and its bright green variety – emerald; this also includes the complex aluminum borosilicate tourmaline, in particular its pink variety – rubbelite; chrysocolla); V) chain (minerals of the pyroxene group: diopside, hedenbergite, diallag, aegirine-augite); G) tape (minerals gr. amphiboles: hornblende uralite, actinolite, tremolite); d) layered, or leaf (minerals of the mica group: talc, phlogopite, lepidolite; clay minerals: kaolinite, montmorillonite; serpentine, or serpentine, as well as its fine-fiber variety – chrysotile-asbestos); e) wireframe (group of feldspars, which is divided into 1) potassium-sodium feldspars, represented by orthoclase, microcline and a green variety of microcline – amazonite; and 2) sodium-calcium floors. spars, or plagioclases, represented in the educational collection by albite and labradorite; nepheline group). 5. Based on the study of minerals of the class of silicates and aluminosilicates, make a written conclusion about the dependence of the external appearance of minerals on the structure of its crystal lattice. Give examples. test questions 1. Give examples of minerals of the following classes: carbonates, sulfides, sulfates, tungstates. 2. What polymorphic varieties of carbon group minerals are found in the earth’s crust? 3. What are the characteristics that distinguish hematite from limonite? 4.Name the properties and distinctive features of minerals – lead, antimony and mercury sulfides. What is the origin of the name natural mercury sulfide? 5. List the types of minerals of the quartz group. 6.What is the name of the rock, in which the minerals predominate – aluminum hydroxides? 7.Name the minerals from the sulfide class, which are ores of copper, zinc, and molybdenum? Write their chemical formulas. 8. What class do the following minerals belong to: labradorite, hornblende, garnet, amazonite? 9. What are the names of the varieties of quartz that are purple, black, or smoky in color? What is the name of clear quartz? 10. Name a mineral from the carbonate group that is a valuable ornamental stone? 11. What is the name of the banded variety of chalcedony? 12. Name the minerals of composition Si O₂, Si O₂ n N₂O, used in jewelry and as ornamental stones. 13.Which class of minerals make up about 75% of the mass of the earth’s crust? 14. What ores are called polymetallic? 15. How do calcite, dolomite, magnesite and siderite interact with hydrochloric acid? Recommended reading 1. Koronovsky N. V.. General geology. – M.: Publishing house “KDU”, 2006. 2. Koronovsky N. V., Yasamanov N. A. Geology. – M.: ACADEMA, 2003. 3. Dobrovolsky V.V.. Geology. – M.: VLADOS, 2001. Feldspar is such a common group of minerals that it makes up almost half the mass of the earth’s crust. The name of this mineral from the class of silicates consists of the Swedish word feldt, which translates as “field”, and the German spath, i.e. “bar” or “plate”. It is called field because it is often found on Swedish arable lands, which are located on moraine deposits. The feldspar mineral is characterized by good cleavage: when struck, it easily splits into plates, hence the “bar” in the name. Humanity has long found use for it in various industries, from industry to jewelry.

Composition and properties of feldspar

To better understand what feldspar is, you should look at its composition. From a chemical point of view, it is an aluminosilicate resulting from the combination of A12O3 (aluminum oxide), Na2O (sodium oxide), K2O (potassium oxide) with SiO2 (silicon dioxide). This composition of feldspar explains its structure: it is characterized by a framework type of crystalline structure and the formation of twin crystals. The mineral can be described as brittle, with an uneven, step-like fracture. The color of the mineral may differ depending on the type of feldspar: the origin and presence of impurities play a significant role here. For example, orthoclase comes in yellow, white, red, and if the color of the stone is blue-black, then you are most likely looking at Labradorite. In addition to the color of the mineral itself, it is also characterized by the color of the trait, which is also the color of the mineral in powder. In the case of feldspar, this color is white. On the Mohs hardness scale (from 1 to 10), position number 6 belongs to feldspar, the properties of which are characterized as follows: the stone can scratch glass, it is processed with a file. Rutile and opal have similar hardness. Density varies from 2,54 to 2,75 g/cm³. For reference: oil has the lowest density, namely 0,8 g/cm³, and the highest density belongs to iridium and is 22,8 g/cm³.

Types of Feldspar

• sodium-calcium (plagioclase);
• potassium;
• potassium-barium, or hyalophanes.

Soda-calcium feldspars make up a significant portion of metamorphic and igneous rocks. The general formula is (Ca, Na)(Al, Si) AlSi2O8. They are characterized by the twinning effect and triclinic crystal structure. Plagioclases include oligoclase, labradorite, albite, bytownite, andesine, and anorthite.

Potassium feldspar has the formula KAlSi3O8. This type of mineral is of igneous origin and is much stronger than representatives of the plagioclase group. The group includes sanidine, microcline, orthoclase and adularia. All of them have one chemical formula, but the ordering of the crystal lattices differs. They can be distinguished from plagioclases by coloring: as a result, plagioclases will change color to red-brown (except for albite).

Potassium-barium feldspars are very rare and are represented by celsian. Formula – BaAl2Si2O8. The value of these cream-colored stones is exclusively collectible. Note that the physical properties of minerals of different subgroups are very similar, despite differences in chemical composition.

Deposits and production

Feldspar makes up a significant portion of the earth’s crust, so it can be found in many parts of the world. There are many deposits in the Russian Federation, here are some of them:

• Northern Caucasus (Karachay-Cherkessia);
• North-Eastern region (Chukotka Autonomous Okrug);
• Southern Siberia (Tuva);
• Transbaikalia;
• Kola region (Murmansk region);
• Southern Urals (Chelyabinsk region);
• Middle Urals (Sverdlovsk region).

Large deposits are known in Sweden, Norway, USA, Ukraine, India, Tajikistan, Japan, and Madagascar. Feldspar deposits come in several types depending on the origin of the mineral. The following are distinguished:

• pegmatite;
• igneous;
• sedimentary;
• weathering;
• hydrothermal;
• metamorphogenic;
• effusive-sedimentary.

Feldspar is mined very actively, because it has applications in a wide variety of industries. It is used to make glass, in ceramics, as a light abrasive, and as a raw material for rubidium. Its role in jewelry is also important: many types of stones are particularly beautiful and are even valued at a tidy sum. In addition, the mineral is credited with magical and healing properties.

Magical properties

Since ancient times, people have tended to attach magical meaning to various objects. Varieties of feldspar are no exception: the beautiful coloring of the stones is of interest to many sorcerers, witches and healers, who find use for the mineral in a variety of practices.

Particularly popular is moonstone, well known for its pale blue color and radiant shimmer. Its other name is adularia. This type of mineral is rare, so albite, sanidine, microcline, labradorite, oligoclase, or even counterfeits made of frosted glass with an iridescence effect are often sold under the guise of moonstone.

As its name suggests, the stone is believed to have a connection with the Moon, so its power is believed to depend on the lunar phases and reaches its peak at the new moon. Moonstone can attract good luck and protect its owner from evil spells, and will help unmarried girls find their soul mate. In addition, it pacifies anger and promotes relaxation and calm. Moonstone is especially recommended for those born under water signs: Pisces, Cancer, Scorpio. Positively affects such chakras as Sahasrara, Ajna, Anahata, Manipura.

Labradorite, often mistaken for a moonstone, is also suitable for use as a talisman. It promotes the development of intuition and hidden abilities, and helps protect the home from harm. If moonstone is good for young people, then labradorite is more suitable for mature, experienced people. Influences the Manipura chakra.

Amazonite helps you become more confident and decisive. This turquoise-colored stone reduces anxiety and brings peace, and gives family people harmony in relationships. By its nature, it carries softness and tenderness, so the fair sex should pay attention to it. Amazonite is suitable for Pisces, Capricorns, Virgos and Libra. Positively affects the Anahata and Vishuddha chakras.

Sunstone (special effect orthoclase) has the ability to bring balance to opposites. In addition, it is responsible for vital energy, strength and joy, helps the development of intuition and wisdom. This type of mineral is good for those who lack positive energy and confidence for new endeavors. Suitable for those born under the signs of Leo and Aries. Affects the Manipura, Anahata and Svadhisthana chakras.

Medicinal properties

Lithotherapy (treatment with stones) actively uses varieties of feldspar. The mineral is believed to have a positive effect on the nervous system and help fight stress. Below is a brief description of the capabilities of the varieties of this stone used:

• Amazonite. Massage with amazonite balls is practiced, as a result of which the condition of blood vessels and skin improves, and metabolism is restored.
• Bull’s Eye (Labrador Retriever variety). Helps lower blood pressure and has a positive effect on the genitourinary system.
• Sanidin. Used for swelling and insomnia. Helps relax.
• Albite. Used for diseases of the liver, stomach, kidneys, spleen. It is advised to apply the stone to the area of ​​the affected organ and leave it there for a while.
• Adular. Used for sleep disorders and overexcitation of the nervous system.

• Labrador. Helps treat impotence and infertility, diseases of the genitourinary system.
• Sun stone (heliolite). Treats nervous disorders, fills with vital energy. Helper in the fight against allergies.

This is just a brief description of the possibilities of using feldspar. The bowels of the Earth are infinitely rich and are capable of providing a person with the necessary resources for both industrial needs and for caring for the body and soul, not to mention the material for creative self-expression. Whatever stones you choose, they will share positive energy with you and add a special charm to the owners of jewelry and accessories made from them.