Aluminosilicate grains

Belite nests (loosely packed) with aluminate-rich melt Coarse aluminosilicate grain, perhaps a feldspar (Miller, 1980)... 

The magnitude of porosity enhancement due to aluminosilicate grain dissolution in a reservoir and source-rock system depends on facies relationships, variations in original composition, formation of subsequent cements, availability of fluid conduits, fluid flux, and the proximity of organic-rich source rocks in hydrologic connection with the reservoir rock. In contrast, carbonate decementation and mass transfer apparently can occur on a scale larger than a specific reservoir and source-rock system (Schultz et al. 1989). 

Main opaque minerals are chalcopyrite, pyrite, pyrrhotite, sphalerite and bornite (Table 2.22). These minerals commonly occur in massive, banded and disseminated ores and are usually metamorphosed. Hematite occurs in red chert which is composed of fine grained hematite and aluminosilicates (chlorite, stilpnomelane, amphibole, quartz) and carbonates. The massive sulfide ore bodies are overlain by a thin layer of red ferruginous rock in the Okuki (Watanabe et al., 1970). Minor opaque minerals are cobalt minerals (cobaltite, cobalt pentlandite, cobalt mackinawite, carrollite), tetrahedrite-tennantite, native gold, native silver, chalcocite, acanthite, hessite, silver-rich electrum, cubanite, valleriite , and mawsonite or stannoidite (Table 2.22). 

Clays are silicate minerals that may be platy or fibrous and are usually of exceedingly fine grain size, ranging from colloidal, a few nanometers in diameter, to a maximum of about a tenth of a micrometer. Similarly to other aluminosilicates, clays show considerable range in chemical composition with concomitant structural modifications (Fig. 2.13). A few of the clay minerals described as fibrous are briefly mentioned here. 

The reason that giant molecules—the aluminosilicate framework-are important here is that these molecules, which look like large grains of sand, are not tarried along in the water, but remain in the watersoftening tank. 

Clay minerals are formed when igneous rocks weather. These minerals are the main constituent of fine-grained (<63 rm) particles in mud. In general these minerals are less cation-rich than their igneous precursors. Kaolinite has the simplest clay mineral formula because it is pure aluminosilicate. It is the mineral that held the secret to making porcelain, which was greatly valued by the emperors of China before AD 1000, after they discovered how hard and clear kaolin becomes when heated to 1300-1400 °C. Other, more complicated clay minerals, e.g. iUite and montmorillonite, have various amounts of cations added to their structures. 

The term clay refers to fine-grained aluminosilicates that have a platy habit and become plastic when mixed with water [11], Dozens of minerals fall under the classification of clays and a single clay deposit can contain a variety of individual clay minerals along with impurities. Clay minerals are classified as phyllosilicates because of their layered structure [12], The most common clay mineral is kaolinite, although others such as talc, montmorillonite, and vermiculite are also abundant. Each of the... 

Assemblages of quartz plus kyanite, sillimanite or andalusite have yielded exceptionally precise and apparently accurate temperatures when applied as a RAM thermometer. Diffusion of oxygen in aluminosilicates is very slow, yielding Tc > 800°C for moderate to coarse grain sizes, while diffusion is comparatively fast in quartz (Table... 

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