Central Research and Development, Experimental Station 356/329
E.I. Du Pont de Nemours
Wilmington, DE 19880-0356, USA
George R. Rossman
Division of Geological and Planetary Sciences
California Institute of Technology
Pasadena, CA 91125, USA
topaz
K'a =6.61 tan 6=0.0005
K'b = 6.82 tan 6=0.0007
K'c =6.81 tan 6=0.0007
orthoclase
K'a =4.69 tan 6=0.0007
K'b = 5.79 tan 6=0.0007
K'c =5.63 tan 6=0.0011
K'11=4.72
K22=5.79
K'33= 5.76
scapolite
K'a = 6.74 tan 6=0.0004
K'c =8.51 tan 6=0.0004
The deviation (C) between measured dielectric polarizabilities as determined from the Clausius-Mosotti equation and those calculated from the sum of ion polarizabilities according to aD(mineral)=SaD(ions) for topaz is 2.5%. The large deviations of orthoclase and scapolite from the oxide additivity rule with A = +7.2 and 1992), ± 17.6%, respectively, are attributed to "rattling" ions in orthoclase and "rattling" (Na,K,Ca) ions and disordered O= and Cl ions in scapolite.