Mineral feldspar-type

Feldspar type of clay. Some clay deposits may include appreciable amounts of quartz. Commercial grades of clays may contain up to 20% quartz. Most abundant group of materials, composed of silicates of aluminium with sodium, potassium, calcium, and rarely barium. Most economically important mineral. Used for ceramics, glass, abrasive wheels, cements, insulation and fertilizer. 

The abyssal clays are composed primarily of clay-sized clay minerals, quartz, and feldspar transported to the siuface ocean by aeolian transport. Since the winds that pick up these terrigenous particles travel in latitudinal bands (i.e., the Trades, Westerlies, and Polar Easterlies), the clays can be transported out over the ocean. When the winds weaken, the particles fell to the sea siufece and eventually settle to the seafloor. Since the particles are small, they can take thousands of years to reach the seafloor. A minor fraction of the abyssal clays are of riverine origin, carried seaward by geostrophic currents. Despite slow sedimentation rates (millimeters per thousand years), clay minerals, feldspar, and quartz are the dominant particles composing the surface sediments of the abyssal plains that lie below the CCD. Since a sediment must contain at least 70% by mass lithogenous particles to be classified as an abyssal clay, lithogenous particles can still be the major particle type in a biogenous ooze. 

The main source is a feldspar-type mineral, poUudte, cesium sodium aluminum silicate, which is mined at Bernic Lake in Canada and also, to some extent, in Bikita in Zimbabwe. 

The common mineral feldspar and the less abundant mineral olivine, selected as examples here, occur widely in many different rock types, and both are broken down during weathering by overall processes (physical and chemical disintegration and degradation). The typical reaction for the weathering of feldspar is shown in Equation 6.1 ... 

Sodium sihcate (41°Bh, 1 3.22 ratio Na20 Si02) is added in the milling operation to disperse the slime, mosdy kaolin. Dispersion also aids the grinding process. The rod mill serves to grind the ore to 0.833 mm (—20 mesh) or to the point where mica, quart2, feldspar, and iron minerals are Hberated. Cyclones, or rake, hydrauhc, or other types of classifiers, are used after grinding to produce coarse and fine mica fractions that are treated separately. 

Clays are composed of extremely fine particles of clay minerals which are layer-type aluminum siUcates containing stmctural hydroxyl groups. In some clays, iron or magnesium substitutes for aluminum in the lattice, and alkahes and alkaline earths may be essential constituents in others. Clays may also contain varying amounts of nonclay minerals such as quart2 [14808-60-7] calcite [13397-26-7] feldspar [68476-25-5] and pyrite [1309-36-0]. Clay particles generally give well-defined x-ray diffraction patterns from which the mineral composition can readily be deterrnined. 

An example of aluminosilicate weathering is the reaction of the feldspar albite to a montmor-illonite-type mineral... 

Principal gangue minerals in base-metal vein-type deposits are quartz, chlorite, Mn-carbonates, calcite, siderite and sericite (Shikazono, 1985b). Barite is sometimes found. K-feldspar, Mn-silicates, interstratified mixed layer clay minerals (chlorite/smectite, sericite/smectite) are absent. Vuggy, comb, cockade, banding and brecciated textures are commonly observed in these veins. 

Cationic flotation of tantalite columbite has also been studied on several ore types that contain tourmaline, feldspar and muscovite as the major gangue minerals [3], The effect of aliphatic mono-amine on flotation of Ta/Nb is presented in Figure 23.3. 

Smith and coworkers recently proposed a specific and novel mineral-based solution to the problem of dilution and diffusion of prebiotic reactants. They have suggested [132-134] the uptake of organics within the micron-sized three-dimensional cross-linked network of pores found to exist within the top 50 xm, or so, of alumina-depleted, silica-rich weathered feldspar surfaces. These surfaces incorporate cavities typically about 0.5 pm in diameter along with cross inter-connections of about 0.2 pm. The nominal area of the weathered feldspar surface is apparently multiplied by a factor of about 130 arising from this network. The similarity of these pores to the catalytic sites in zeolite-type materials is pointedly mentioned. 

Feldspars are the most abundant minerals in the earth s crust, accounting for about 60% of all igneous rocks. They are derivatives of silica in which about one-half or one-quarter of the silicon atoms have been replaced by aluminum. Feldspar is used in the manufacture of certain types of glass and pottery. Some feldspar crystals, such as moonstone (white perthilte), Amazon stone (green microcline), and multicolored labradorite, are used as gem stones and in architectural decorations. Some are used as a coating and filler in the production of paper. 

In this case, it is not necessary to overcome an energy barrier for nucleation to occur. Decomposition into two phases occurs without involving the process of nucleation. Separation into two phases in this type of system is called spinodal decomposition, and is seen among silicate minerals such as the pyroxene and feldspar groups. Generally, the boundaries between the two phases are wavy rather than flat, but the two phases are in a specific crystallographic relation. 

The mineral types familiar in sediments and sedimentary rocks are present micas, mica-like phases, fully expandable phases and mixed layered series. In a sense, celadonite mica is isolated from dioctahedral mica by a multiphase zone where montmorillonite is stable with a feldspar and mica. It is evident that the only way to. produce celadonite mica under high potassium concentrations is by having a proper bulk composition toward that of celadonite. The possibility of producing celadonite in a potassium deficient system, i.e., where montmorillonite coexists with a non-alkali bearing phase, has not yet been studied experimentally. 

Lahradoriie is the characteristic feldspar of the more basic rock types like diorite. gahbro. andesite or basalt and it is usually associated with some one of the pyroxenes or amphiholes. Lahradoriie frequently shows a heauliful play of iridescent colors due lo minute inclusions of another mineral. However, the labradorescent phenomenon has not been fully determined. The classic location for this mineral is. of course. Labrador, whence its name. Il is a constituent there of the rock anorthosite and is found in the anorthosites of the Provinces of Quebec and Ontario, and in the Adirondack region in New York Stale. 

Pegmatites represent a residual phase of igneous depositions, characterized by extremely coarse crystalline material, that results Ironi the presence of associated volatiles, e.g.. water vapor, carbon dioxide, sulfur dioxide, and others, which decrease tile viscosity and facilitate crystallization. Quartz, feldspar, and mica are the more common minerals found in this environment. but Mich bodies are also hosts for many rare minerals and several types of gem stones, e.g.. beryl, tourmaline, and topaz. 

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