[Chemical composition] The chemical composition of the garnet family mineral is A 3 B 2 [SiO 4 ] 3 . Wherein A represents a divalent cation Mg 2+ , Fe 2+ , Mn 2+ , Ca 2+ , etc. and Y, K, Na, etc., B represents a trivalent cation Al 3+ , Fe 3+ , Cr 3+ , V 3+ And Ti 4+ , Zr 4+, and the like. Class A and B cations each pair can form a series of garnet ore species, but more common the following two main series, i.e. type A large radius cation is Ca 2+ (referred calcium iron garnet series) and a Mg 2+ cations is smaller radius, Fe 2+, Mn 2+ (referred Fe series aluminum garnet). Magnesium aluminum garnet (Pyrope) Mg 3 A l2 [ SiO 4] 3 Iron aluminum garnet (Almandite) Fe 3 A l2 [SiO 4 ] 3 Manganese aluminum garnet (Spessartite) Mn 3 A l2 [[SiO 4 ] 3 Calcium iron garnet series (ie A is mainly Ca): Ca 3 (Al, Fe, Cr, Ti, V, Zr) 2 [SiO 4 ] 3 Calcium aluminum garnet (Grossularite) Ca 3 A l2 [SiO 4 ] 3 Calcium iron garnet (Andradite) Ca 3 Fe 3+ 2 [SiO 4 ] 3 Calcium chrome garnet (Uvarovite) Ca 3 Cr 2 [SiO 4 ] 3 Calcium vanadium garnet (Goldmanite) Ca 3 Cr 2 [SiO 4 ] 3 Calcium zirconium garnet (Kimzeyite) Ca 3 Zr 2 [SiO 4 ] 3 Class A and Class B are widely developed in the same way as each other. Therefore, garnets of pure endmembers in nature are rare, and are generally "mixtures" of several end users. [Crystal structure] equiaxed crystal system; O 10 h -Ia3d; a 0 = 1.146 to 1.248 nm; Z = 8. In the crystal structure, the isolated [SiO 4 ] tetrahedron is bonded by a coordination octahedron [BO 6 ] composed of a B-type cation (Al 3+ , Fe 3+ , Cr 3+ , V 3+ , etc.); Some of the larger cubes can be seen as distorted cubic voids occupied by class A cations, which are distorted cube-coordinated polyhedra [AO 8 ]. Figure G-6 Calcium aluminum garnet crystal structure (showing three coordination forms) (quoted from Pan Zhaoyu et al., 1993) Figure G-6 shows the crystal structure of calcium aluminum garnet Ca 3 A l2 [SiO 4 ] 3 : [AlO 6 ] octahedron is associated with the surrounding six [SiO4] tetrahedral co-angled tops, and one [ The CaO 8 ] distortion cube is connected by a common edge. Each O 2 - is associated with one Al and one Si and two farther Cas. The crystal structure of garnet is relatively tight, with the most compact direction along the third axis and the strongest chemical bond. However, in garnet crystals, O 2- is not the closest packing. Because Ca 2+ ions are large, they are not suitable for filling into tetrahedral and octahedral voids formed by the most close packing of O 2- , but are [CaO 8 ] cubic coordination polyhedrons. The crystal structure of garnet can be transformed under high pressure, namely: → Increase with pressure Mg-rich garnet - → spinel + stishovite - → perovskite Fe-rich garnet - → ilmenite type - → perovskite type [Form] It is usually in a good crystal form (Fig. G-7). The rhombohedral dodecahedral crystal face often has a parallelogram with long parallel lines. Sometimes the sensing surface is visible. The aggregates are often dense or dense. Figure G-7 garnet crystal (quoted from Pan Zhaoyu et al., 1993) Diamond dodecahedron: d{110}; tetragonal octahedron: n{211} [Physical properties] Various colors (Table 21-3), it is affected by composition (such as calcium-chromium garnet because of the chrome is bright green), but there is no strict regularity; glass luster, fracture grease luster. No clerk. Hardness 6.5 ~ 7.5. The relative density is 3.5 to 4.2, generally the content of iron, manganese and titanium increases, and the relative density increases. It is brittle (such as the development of cracks in garnets commonly found in flakes, which is caused by brittleness). (quoted from Pan Zhaoyu et al., 1993) [genesis and occurrence] garnet is widely distributed in various geological processes in nature, and the main components of various garnets The production is listed in Table 21-4. (quoted from Pan Zhaoyu et al., 1993) In addition, garnet is widely distributed in sand mines due to its stable nature. After garnet when the latter suffered intense hydrothermal alteration and weathering subject, it can be transformed into chlorite, sericite, limonite and so on. Different mineral species in garnet family minerals have different genetic characteristics. In addition to the chemical composition of the geological environment, they are also related to the size of the class A cation and the stability of the eight-coordinated cube. Lin law shows that, when the anion same size (in the garnet are unified to O 2-), the larger the cationic, coordination number (i.e. the number of O 2- with the ligand) more; than when cation In hours, in order to achieve a high coordination number, it is necessary to increase the pressure. The coordination number of the class A cations Ca 2+ , Mn 2+ , Fe 2+ , Mg 2+ , etc. in garnet is 8. The radius of these ions is successively decreased by Ca 2+ (0.098 nm), Mn 2+ (0.096 nm), Fe 2+  (0.092 nm), and Mg 2+ (0.089 nm). Ca 2+ has eight coordination times and requires little pressure. Therefore, calcium aluminum garnet and calcium iron garnet are generally formed under contact metamorphism; Mn 2+ , Fe 2+ and Mg 2+ tend to be in general. In the case of six coordination, when eight coordination is required, it is generated under the condition of increased pressure, so the manganese aluminum garnet is formed under the condition of low pressure in the lower pressure region, and the iron-aluminum garnet is at a higher pressure. generating intermediate area under metamorphic conditions, and magnesium aluminum garnet can only be generated under high pressure conditions, such as eclogite, Kimberley rock, has been widely looking at it as a sign of diamond. The physical properties of garnet are also of a metrical significance. For example, the purple series of magnesium-aluminum garnet in diamond-bearing kimberlite in Shandong Province, China, the relative density value is mostly greater than 3.75. [Identification characteristics] According to its equiaxed characteristic crystal form, grease gloss, lack of cleavage and high hardness are easily recognized. However, accurate identification of mineral species requires X-ray diffraction analysis and determination of composition, relative density and refractive index. [Main use] Use its high hardness as the abrasive material. Large grain (>8mm, green can be as small as 3mm), and beautiful color, transparent and flawless, can be used as gem material. Some laser materials have a garnet structure, such as yttrium aluminum garnet Y 3 Al 2 [AlO 4 ] 3 . Cutting Machine is a machine that shears a sheet by reciprocating linear motion with one blade relative to the other. By means of the moving upper blade and the fixed lower blade, a reasonable blade gap is applied to apply shearing force to the metal sheets of various thicknesses, so that the plates are broken and separated according to the required size. Cutting Machine Hydraulic Cutting Machine,Sheet Metal Cutting Machine,Cutting Plate Machine Cangzhou Feiyang Machiney Manufacturing Co., Ltd. , https://www.coldformingmachines.com
Iron-aluminum garnet series (ie A is mainly Mg, Fe, Mn): (Mg, Fe, Mn) 3 A l2 [SiO 4 ] 3 
The general name for the garnet family of minerals; named after the shape of pomegranate seeds.