Microcline and Plagioclase

For separation between microcline and plagioclase X-ray excited luminescence is used (Gorobets et al. 1997). The main problem is that their emission spectra are very close. Under laser excitation these minerals also demonstrate blue emissions connected with Eu ", which have close spectral and kinetic parameters. Nevertheless, the differences in excitation spectra (Fig. 8.5) enable effective sorting. 

Moroshkm V, Gorobets B, Bushev A (1987) Luminescence of microcline and plagioclases from mica p egmatites as their exploration and genetic guides. Izvestiya Acad Nauk SSSR (Geol)... 

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.

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. 

Because the main reason of microcline-plagioclase sorting is to control the Na/K ratio, LIBS may be excellent separation technology. The analytical lines of Na and K are very strong and specific in order to promise confident identification (Fig. 8.6). 

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. 

Feldspar averages 3.5% (range 0-8%) and is predominantly plagioclase. Microcline is rare. Most grains show signs of dissolution and diagenetic alteration (replacement by carbonate). 

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. 

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