Potassium mica

From the clay mineral-zeolite associations found at low temperatures, it is apparent that kaolinite as well as potassium mica occur rarely with alkali zeolites. Such assemblages are known for highly alkaline waters in continental lakes (Hay, 1966 Sheppard and Gude, 1969) where montmoril-lonite is nevertheless the predominant clay mineral. At higher temperatures, where most alkali zeolites become unstable but analcite persists, mont-morillonite will be present up to 100°C and a mixed layered mineral above this temperature. 

The major aluminous clay minerals, alkali zeolites and feldspars which are most commonly associated in nature can be considered as the phases present in a simplified chemical system. Zeolites can be chemiographically aligned between natrolite (Na) and phillipsite (K) at the silica-poor, and mordenite-clinoptilolite at the silica-rich end of the compositional series. Potassium mica (illite), montmorillonite, kaolinite, gibbsite and opal or amorphous silica are the other phases which can be expected in... 

The phases commonly considered to be present at 25°C 1 atmosphere are glbbs-lte, kaolinite, albite,-montmorillonite, potassium mica (dioctahedral)... 

FOSTER (M.D.), 1956. Correlation of dioctahedral potassium micas on the basis of their charge relations. U.S. Geol. Sur. Bull. 1036-D, 57-67. 

One set of aluminosilicate equilibrium relationships for which some quantitative data are available is depicted in Figure 5. This figure (25° C) is derived from information presented and discussed by Hemley (15), Feth, Roberson, and Polzer (8), and Garrels and Christ (11). The dual boundaries between potassium mica (muscovite) and kaolinite reflect the roughly estimated uncertainty in the equilibrium constant. The relationship of this boundary to actual K -H+ ratios in sea water may be... 

In a part of this system which has been studied by Hemley (11), four phases can exist at equilibrium aqueous solution, solid quartz, solid kaolinite (Al1 Si2Or)(OH)4), and potassium mica (KAl tSi 4Oio(OH)2). The variables are p, T, and the various concentrations [K+], [IF], [CT], [Al]a(J, [Si(OH)4].i(, etc. If we apply the phase rule (Equation 1) to equilibria of the four phases mentioned, we find F = 5 -f 2 — 4 = 3. The most practical choice of independent variables would seem to be p, T, and [CT]. These are easy to control, and CT is the one ion that must remain in the aqueous phase since there is no place for it in the solid phases. The phase rule now states that after the values for these... 

Sillen constructed his models in a stepwise fashion starting with a simplified ocean model of five components [HCl, H2O, KOH, Al(OH)3, and Si02] and five phases (gas, liquid, quartz, kaolinite, and potassium mica) (Sillen, 1967). His complete (almost) seawater model was composed of nine components HCl, H2O, and CO2 are acids that correspond to the volatiles from the Earth KOH, CaO, Si02, NaOH, MgO, and Al(OH)3 correspond to the bases of the rocks. If there was an equilibrium assemblage of nine phases, the system would have only two independent variables. Sillen argued that a plausible set could include a gas phase and a solution phase and the following seven solid phases ... 

Schroeder PA (1990) Far infrared. X-ray powder diffraction, and chemical investigation of potassium micas. Am Mineral 75 983-991... 

The distinction between light and dark micas became almost synonymous with "potassium micas" and "ferro-magnesium micas". 

Potassium makes up 2.6% by weight of the Earth s crust. The element is enriched in acid magmatic rocks such as granite, containing potassium mica (muscovite) and potassium feldspar (orthoclase KAlSijOg, 13.9% K). In sediments and weathering... 

The sodium concentration of soils is determined by the geological origin of the rocks. All minerals of the feldspar group (sodium feldspar, potassium feldspar, calcium feldspar), potassium mica and hornblende are rich in sodium. The same applies to the clay minerals montmorillonite and illite. 

Lepidolite is a lithium potassium mica it also belongs to the class of aluminum silicates. Various empirical formulas have been proposed for it, probably because its actual composition varies somewhat. In fact, none of these minerals are pure crystals of definite composition. Of the lepidolite deposits which have been discovered in the United States so far, none warrant mining today. Lepidolite is processed in the United States, but the ore is imported from southern Africa. 

Potassium micas, feldspars (K), micaceous clays (illite), radioactive evaporates,... 

Cook, M. G., and C. I. Rich, 1962. Weathering of sodium-potassium mica in soils of the Virginia piedmont. Soil Sci, Soc. Am. Proc. 26 591-595. 

Correlation of dioctahedral potassium micas on the basis of their charge relations. 

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