Phlogopites

Phospha.tes. Many phosphates cl aim unique material advantages over siUcates that make them worth the higher material costs for certain apphcations. Glass-ceramics containing the calcium orthophosphate apatite, for example, have demonstrated good biocompatibiUty and, in some cases even bioactivity (the abiUty to bond with bone) (25). Recent combinations of fluorapatite with phlogopite mica provide bioactivity as well as machinability and show promise as surgical implants (26). 

Muscovite mica formed as a primary mineral in pegmatites and granodiorite differs in physical properties compared to muscovite mica formed by secondary alteration (mica schist) (Table 2). The main differences are in flexibiUty and abiUty to be delaminated. Primary muscovite is not as brittle and delaminates much easier than muscovite formed as a secondary mineral. Mineralogical properties of the principal natural micas are shown in Table 3. The make-up of muscovite, phlogopite, and biotite are as follows ... 

Property Muscovite Phlogopite Biotite Synthetic fluorophlogopite... 

All micas have a vitreous luster phlogopite luster can range from vitreous to submetaUic. 

Tensile strength compression strength for muscovite and phlogopite is 221 MPa. To convert MPa to psi, multiply by 145. Chemically combined. 

Segment plate, used as insulation between copper commutator segments on direct-current universal motors and generators, accounts for the primary use for built-up mica. Phlogopite built-up mica is preferred for these segments because it wears at the same rate as the copper segments. 

A 1.0 nm basal spacing exhibited in a diffractogram peak that is somewhat broad and diffuse and skewed toward wider spacings characterizes the x-ray diffraction pattern of iUite. Polymorphs may be present (120). Muscovite derivatives are typicaUy dioctahedral phlogopite derivatives are trioctabedral. 

Silicates with layer. structures include some of the most familiar and important minerals known to man, partieularly the clay minerals [such as kaolinite (china clay), montmorillonite (bentonite, fuller s earth), and vermiculite], the micas (e.g. muscovite, phlogopite, and biotite), and others such as chrysotile (white asbestos). 

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. 

Figure 21. Fits of lattice strain model to experimental phlogopite-melt partition coefficients for 1+ and 2+ cations on the large X-site for mn 6+6 of Icenhower and London (1995) at 0.2 GPa and 650°C. 1+ data can be readily fitted 2+ data were fitted by assuming that = lE = 100 GPa. Note that r (x) is slightly larger than rsa, making this site ided for incorporation of Ra. Errors bars, when larger than symbol, are 1 s.d. Ionic radii in Xll-fold coordination are taken from Shaimon (1976).

Figure 22. Variation in phlogopite-melt Db with reciprocal temperature. The low temperature data of Icenhower and London (1995) define a strong linear trend. At higher temperature, no trend is apparent, and the data fall into two distinct clusters the highDea points of Green et al. (2000) and La Tourrette et al. (1995) and the low L>Ba points of Schmidt et al. (1999) and Guo and Green (1990). The cause of these differences is utuesolved.

There are no noble gas partition coefficients for phlogopite. The large size and low mean charge of the large X-site (Zg )) suggest that noble gases could be readily incorporated into phlogopite. 

In most minerals the U-series elements are highly incompatible. There are, however, several exceptions. We calculate that radium will be compatible in phlogopite and alkali-feldspar and that these two minerals will dominate the magmatic radium budget in cases... 

Foley SF, Jackson SE, Fryer BJ, Greenough JD, Jenner GA (1996) Trace element partition coefficients for clinopyroxene and phlogopite in an alkaline lamprophyre from Newfoundland by LAM-ICP-MS. Geochim Cosmochim Acta 60 629-638... 

Guo J, Green TH (1990) Experimental study of barium partitioning between phlogopite and sihcate liquid at upper-mantle pressure and temperature. Lithos 24 83-96 Harrison WJ, Wood BJ (1980) An experimental investigation of the partitioning of REE between garnet and liquid with reference to the role of defects. Contrib Mineral Petrol 72 145-155 Hart SR, Duim T (1993) Experimental cpx/melt partitioning of 24 trace elements. Contrib Mineral Petrol 113 1-8... 

Schmidt KH, Bottazzi P, Vannucci R, Mengel K (1999) Trace element partitioning between phlogopite, clinopyroxene, and leucite lamproite melt. Earth Planet Sci Lett 168 287-299 Shaimon RD (1976) Revised effetive ionic radii and systematic studies of interatomic distances in halides and chalcogenides. Acta Cryst A32 751-767... 

Olafsson M, Eggler DH (1983) Phase relations of amphibole, amphibole-carbonate, and phlogopite-carbonate peridohte petrologic constraints on the asthenosphere. Earth Planet Sci Lett 64 305-315 Olson P, Schubert G, Anderson C, Goldman P (1988) Plume formahon and lithosphere erosion a comparison of laboratory and numerical experiments. J Geophys Res 93 15065-15084 Pearson DG, Shirey SB, Carlson RW, Boyd FR, Nixon PH (1995) Stabilisahon of Archean lithospheric manhe A Re-Os isotope isotope study of peridohte xenoliths. Earth Planet Sci Lett 134 341-357... 

Wendlandt RF, Eggler DH (1980) The origins of potassic magmas 2. Stability of phlogopite in natural spinel Iherzolite and in the system KalSi04-Mg0-H20-C02 at high pressures and high temperatures. Am J Sci 280 421-458... 

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