Clintonite-1M; crystal chemistry and its relationships to closely associated Al-rich phlogopite

Upper limit of the tetrahedral rotation angle and factors affecting octahedral flattening in synthetic and natural 1M polytype C2/m space group micas

“…The origin of octahedral ß attening has been analyzed in many structural and crystal chemical studies (e.g., Hazen and Wones 1972;Toraya 1981;Lin and Guggenheim 1983;Bailey 1984a;Weiss et al 1985Weiss et al , 1992Alietti et al 1995Alietti et al , 1997Brigatti and Davoli 1990;Brigatti and Poppi 1993;Brigatti et al 1991Brigatti et al , 1996aBrigatti et al , 1996bBrigatti et al , 2000aBrigatti et al , 2000bBrigatti et al , 2001Brigatti et al , 2003aCruciani and Zanazzi 1994;Brigatti and Guggenheim 2002;Redhammer and Roth 2002), but so far relatively few researchers have exploited predictions from geometric crystal chemical models to assess octahedral ß attening (e.g., Donnay et al 1964a;Hazen and Wones 1972;Hazen and Burnham 1973;Takeda and Morosin 1975).…”

Fundamental difference between synthetic powder and natural or synthetic single-crystal 1M micas: Geometric homo-octahedral vs. geometric meso-octahedral sheets

“…Several authors have noted correlations between differences of structural parameters characterizing the M1 and M2 sites in 1M micas of C2/m symmetry (e.g., Brigatti and Davoli 1990;Brigatti et al 1991;Redhammer and Roth 2002;Lin and Guggenheim 1983;Alietti et al 1997), but none of them have stressed that such relationships can be explained by geometrical models that admit site-specifi c uniform bond lengths for M1 and M2 sites in an octahedral sheet of uniform height (this is exploited in the interpretations and analyses given below). Weiss et al (1985Weiss et al ( , 1992 obtained high correlations by plotting absolute differences of ψ angles in a sheet, that is |ψ M1 -ψ M2 |, |ψ M2 -ψ M3 |, and |ψ M3 -ψ M1 |, against corresponding differences of counter-rotation δ angles.…”

“…Many authors have studied the geometry of cationic sites in the octahedral sheets of 1M polytype C2/m space group micas (e.g., Bailey 1984;Toraya 1981;Lin and Guggenheim 1983;Weiss et al 1985Weiss et al , 1992Alietti et al 1995Alietti et al , 1997Brigatti and Davoli 1990;Brigatti and Poppi 1993;Brigatti et al 1991Brigatti et al , 1996aBrigatti et al , 1996bBrigatti et al , 2000aBrigatti et al , 2000bBrigatti et al , 2001Brigatti et al , 2003aCruciani and Zanazzi 1994;Brigatti and Guggenheim 2002;Redhammer and Roth 2002), but so far only a few researchers have emphasized the utility of geometrical models in assessing both the octahedral geometry (i.e., the octahedral dimensions and the octahedral distortions) and the complex crystal chemistry of these minerals (e.g., Donnay et al 1964a;Hazen and Wones 1972;Hazen and Burnham 1973;Takeda and Morosin 1975). We follow and extend the latter approach (Mercier et al 2005).…”

Clintonite-bearing assemblages in chondrodite marbles from the contact aureole of the Třebíčský Pluton, Moldanubian Zone, Bohemian Massif

“…It exhibits a wide stability field in PTX diagrams but restricted to low X CO2 . Clintonite also requires specific chemical composition characterized by very high Al/Si ratio and low activity of Na and K (Olesch Seifert 1976, Rice 1983, Ulmer 1983, Ackermand et al 1986, Alietti et al 1997, Mottana et al 2002. Its crystal chemistry was studied in detail by MacKinney et al (1988), but the authors did not provide any information about mineral assemblages of the studied clintonite samples.…”