Microcline feldspar

Similarly to Mn(IV)- and Fe(III)-oxides, some primary minerals were shown to promote polymerization of hydroquinone (19). Olivines, pyroxenes, and amphiboles accelerated the polymerization reaction to a greater extent than micas and feldspars. Microcline and quartz were ineffective- The effect was greatest for tephroite, a manganese-bearing silicate with the ideal chemical formula M SiO. Fayalite, the corresponding Fe(II) analog (Fe2Si0 ), was effective, but to a lesser extent. 

The formation of amorphous volatile products during carbothermal reduction processes can cause problems by condensing in the cooler parts of the furnace and altering the composition of the original mixture. Al NMR shows that these amorphous phases all contain Al solely in tetrahedral coordination, with chemical shifts consistent with the potassium feldspars microcline and sanidine (54-58 ppm). Thermodynamic analysis confirmed the feasibility of vapour-phase transport of both Al and alkali metal impurities from the clay which can then condense to form short-range feldspar-like units (Ekstrom et al. 1996). 

Other minor constituents are authigenic pyrite which appears as framboides or separate crystals secondary gypsum, mainly as vein filling detrital quartz grains and authigenic feldspar (microcline). 

Figure 7.1 Goldich s sequence of increasing weatherability of common minerals (cf. Loughnan 1969 Faure 1991). In parentheses are the lifetimes in years from Table 7.1, assuming olivine = forsterite, augite = diopside, hornblende = tremolite, Ca-plagioclase = anorthite, Na-plagioclase = albite, K-feldspar = microcline, and the stability of muscovite is comparable to that of the related clay, illite.

Thermodynamic principles are used by soil scientists and geochemists to define solution conditions favorable for the formation of particular minerals. Consider dissolution of the feldspar, microcline, for example ... 

Feldspar Microcline (composition KgO AI2O3 6Si02 AI2O3 0.180 5.556 Source of AI2O3... 

Plagioclase feldspar (Na-Ca aluminosilicate), other than albite, stains red potash feldspar (microcline or orthoclase) stains yellow, and quartz and glassy slag are unstained. Calcite takes on various shades of pink and dolomite may be deep red. The particles are normally examined in immersion mounts, utilizing liquids of known index of refraction and a cover glass. 

Granite-II Igneous Composed mainly of quartz, Alkali-feldspar (microcline) and muscovite. Granular texture. Plagioclase and biotite are minor... 

Feldspars (microcline, orthose, plagioclases) Glass Industry for porcelain, enamels and glazes. 

Pegmatitic alkalitic (peralkaline) granites are distinct both geologically and chemically from calc-alkaline granites and granodiorites. They generally are holocrystalline and leuco- to mesocratic and consist of 25-40% quartz, about 50% alkali feldspar (microcline, perthite, or late forming albite) and 10-25% accessories (pyroxenes, amphiboles, etc.). 

In our second example, we calculate the same ratio for the reaction between muscovite and potassium feldspar (KAlSiaOs maximum microcline in the database) in the presence of quartz ... 

In an example of a sliding temperature path, we consider the effects of cooling from 300 °C to 25 °C a system in which a 1 molal NaCl solution is in equilibrium with the feldspars albite (NaAlSiaOs) and microcline (KAlSisOg), quartz (SiC>2), and muscovite [KAl3Si30io(OH)2]. To set up the calculation, we enter the commands... 

To test whether the mixing hypothesis might explain the diagenetic alteration observed, we begin by equilibrating the fresh water, assuming equilibrium with the potassium feldspar ( maximum microcline in the database), quartz, and muscovite (a proxy for illite) in the formation. In REACT, we enter the commands... 

Roughly, 0.18% of the total mineral composition containing Fe203 in the brown clay was detected by XRD. Other minerals like quartz, K-feldspar, muscovite, microcline, mica, and pyrite were also identified by XRD data. 

Blasi A., Brajkovic A., and De Pol Blasi (1983). Dry-heating conversions of low microcline to high sanidine via a one-step disordering process. Abstr. NATO Advanced Study Inst, on Feldspars and Feldspatoids, Rennes, France. 

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. 

The Hostrock and Backfill Material. Most crystalline igneous rocks, including granite and gneiss, are composed of a comparatively small number of rock forming silicate minerals like quartz, feldspars (albite, microcline, anorthite etc.) micas (biotite, muscovite) and sometimes pyroxenes, amphiboles, olivine and others. Besides, there is a rather limited number of common accessory minerals like magnetite, hematite, pyrite, fluorite, apatite, cal cite and others. Moreover, the weathering and alteration products (clay minerals etc.) from these major constituents of the rock would be present, especially on water exposed surfaces in cracks and fissures. 

PERTHITE. An alkali feldspar comprising parallel or subparallel inlergrowths. The potassium-nch phase, usually microcline, seems to be the host from which the sodium-rich phase, usually albite inclusions, exsolved. The exsolved areas typically form blebs, films, lamellae, small strings, or irregular veinlets and usually are visible to the naked eye. 

The autoradiographs also show some sorption on the granite obtained from the Eye-Dashwa Lakes pluton (Figure 6). Even though the iron concentration is low, hydrothermal alteration of the granite has resulted in the infilling of the minute fractures in the microcline feldspar with iron oxides, which show technetium sorption, while there is no sorption on the biotite crystals. 

Some of the most common igneous minerals are quartz, potassium feldspars (orthoclase and microcline), plagioclase feldspars (albite, anorthite), micas (muscovite, biotite), olivine, and members of the amphibole and pyroxene groups. Many other minerals are found in igneous rocks, most of which occur in only very small amounts. These are called accessory minerals, the most common of these are corundum, pyrite, magnetite, zircon, rutile, apatite, and members of the garnet group. 

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