Na-phlogopite

Volfinger, M. (1975) Effet de la temperature sur les distributions Na, Rb et Cs entre la sanidine, la muscovite, la phlogopite et une solution hydrothermale sous une pression de 1 kbar. Geochim. Cosmochim. Acta, 40, 267-282. 

Fung P. C. and Shaw D. M. (1978). Na, Rb and T1 distributions between phlogopite and sani-dine by direct synthesis in a common vapour phase. Geochim. Cosmochim. Acta, 42 703-708. 

In Germany, a silica-phosphate glass-ceramic has been developed and used clinically. It consists of fluorhydroxyapatite (Caio(P04)e(OH,F)2) and phlogopite ((Na,K)Mg3(AISi30io)F2), a type of mica [88,94-96],... 

If we consider the three types of substitutions dioctahedral, trioctahedral and interlayer ion, we see that Na and trioctahedral minerals are stable to higher temperatures than others. This is logical when one considers that sodic trioctahedral magnesian minerals are unknown, paragon-ite is unstable below about 340°C (Chatterjee, 1968) and phlogopite is unstable below 250°C (Velde, unpublished). By contrast muscovite appears stable at low temperatures under high K O concentration (Velde, 1969) or appropriate H+, K+ and SiO activities (Garrels and Howard, 1959). 

The mica group has about 30 members but only a few are common. Muscovite, phlogopite, and biotite are important representatives of this group. Muscovite is one of the most common of the micas and occurs in a wide variety of geological environments because of its stability. Crystals measuring 2-3 m across are mined in some locations. Muscovite can vary in chemical composition as a result of atomic substitution (Na for K Mg and F for Al). 

Phlogopite is found in metamorphosed magnesium-rich limestones, dolomites, and ultrabasic rocks. Biotite, similar to muscovite, is also widespread. It is usually associated with minerals which were formed under high temperature and pressure. Several elements, other than those included in their typical chemical composition, can be found in these two minerals. These include Na, Rb, Cs, Ba, F, and Ca. The most important difference between phlogopite and biotite is that biotite contains a substantial amount of iron. 

For large cations such as Cs and Rb (e.g., Cs-tetra-ferri-annite, Rb-,Cs-rich phlogopite, and nanpingite) the small a value corresponds to a large interlayer separation, whereas for small cations such as Na and Ca (e.g., preiswerkite, paragonite, and... 

Figure 6. Bulk modulus as a function of interlayer cation size, calculated using the interlayer chemical composition. Na(Pg) paragonite (Comodi and Zanazzi 1997) Na(mu) Na-rich muscovite (Comodi and Zanazzi 1995) K(phl) phlogopite (Hazen and Finger 1978) K(mu) K-muscovite (Comodi and Zanazzi 1995) Cs(Cs-tfa) Cs-tetra-ferri-annite (Comodi et al. 1999) Rb(Rb-tfa) Rb-tetra-feni-annite (Comodi et al. 2001).

CHEMICAL PROPERTIES noncombustible solid generally resistant to chemical attack exceptions are muscovite (which decomposes in hydrofluoric acid) and phlogopite (which is mildly attacked by hydrochloric acid and decomposes in hot sulfuric acid) it is dielectric FP (NA) LFL/UFL (NA) AT (NA) pH (neutral) IR (1.58). 

If Si " is substituted by AE in one-fourth of the tetrahedral sites, one monovalent cation in the 12-fold coordination site (like K, Na etc.) can balance the excess negative charge. Example illite, muscovite, paragonite (dioctahedral), biotite, phlogopite (trioetahedral) etc. 

Hoda and Beall (1982) developed a glass-ceramic free of alkaline ions, such as Na, K", or Li. The main crystal phase was formed of alkali-free phlogopite. The investigations of Hoda and Beall (1982) concentrated on the formation of the main crystal phases of... 

---