Mica definition

The micas, as a class, are difficult to grind to a fine powder one exception is disintegrated schist, in which the mica occurs in minute flakes. For diy grinmng, hammer mills equipped with an air-transport system are generally used. Maintenance is often high. It has been established that the method of milling has a definite effect on the par-... 

Insulation systems were first classified according to the material used, and permissible temperatures were established based on the thermal aging characteristics of these materials. For example. Class B insulation was defined as inorganic materials such as mica and glass with organic binders 130°C was the allowable maximum operating temperature. The present definition of insulation system Class B stipulates that the system be proven. . by experience or accepted tests. .. to have adequate life expectancy at its rated temperature, such life expectancy to equal or... 

Asbestos is a nonspecific, collective term for a group of fibrous minerals. A sample called asbestos may be composed of one or more of the six minerals listed above and may contain small amounts of other nonfibrous silicate minerals, such as quartz, feldspar, or mica. The definition of asbestos recently published by the American Society for Testing Materials (Ross et al., 1984) can be found in the Glossary. 

Note 2 See Definition 5.22, note 6 rf = Mica may be used to evaluate the out-of-phase viscosity. 

Natural mica compositions of the dioctahedral, potassic types have been discussed by Velde (1965b) in connection with the solid solution between muscovite and the different celadonite mica molecules. It was shown that both natural and synthetic micas formed two distinct compositional and genetic groups. The important point made in the discussion is the definition of the term mica. The most restrictive criteria as was mentioned before is the necessity for the mineral in question to have a net charge (the sum of octahedral and tetrahedral electrostatic... 

Absorbance spectra monolayer on mica, 244/ thickness of mica sheet, 241 Absorptivity ratios, definition, 28 Acyl chains, monolayer films, 198 Adatom(s) definition, 210 surface migration, 211214... 

That the atomic weight of uranium lead is extremely variable has already been shown. In order to interpret this variability its sources must be studied both geologically and mineralogically. On the geologic side of the question the uranium ore can be divided in to three principal classes, which are sharply distinct. The definitely crystallized varieties of uraninite occur in coarse pegmatites, associated with feldspar, quartz, mica, beryl, and other minor accessories. The massive pitchblende is found in metalliferous veins, together with sulphide ores of copper, lead, iron, zinc, and so forth. As for camotite, that is a secondary mineral, found commonly as an incrustation on sandstone, and often, also upon fossil wood. There may be other modes of occurrence, but these are the most distinctive. 

Know the basic structures of the major clay and mica mineral groups and the definitions of octahedral, dioctahedral, gibbsite, brucite, and tetrahedral layers. 

In the homo-octahedral family, the three M sites are by definition identical in content and size. Any difference in one of the M sites violates the H centering, lowering the symmetry of the O sheet to that of the meso-octahedral family. A difference between the other two M sites destroys also the inversion center and lowers the symmetry of the O sheet to that of the hetero-octahedral family. From the practical viewpoint, differences among the M sites are often small and must be evaluated on statistical grounds. As discussed by Bailey (1984c) for the specific case of micas [cf. an application in Amisano-Canesi et al. (1994)], if o/ is taken as the estimated standard deviation (esd) of an individual quantity and o = Oiln is the esd of the mean of n values, the esd of a difference (A) between two mean values is given by (3 = Two quantities are... 

The conventional layer of mica is described in details in Ferraris and Ivaldi (this volume). Here we recall only those definitions that are referred to in the following. 

Figure 13. Definition of the S, and axial settings of mica polytypes.

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