The dielectric constants and dielectric loss values of 4 Ca-containing minerals were determined at 1 MHz using a two-terminal method and empirically determined edge corrections. The results are: ! vesuvianitel tca = 9.93 tan 6 = 0.006 ~:'c = 9.79 tan 6 =0.005 vesuvianite2 ~C' a = 10.02 tan 6 = 0.002 K' c = 9.85 tan 3=0.003 zoisitel ~:'a = 10.49 tan 3 = 0.0006 t ~b = 15.31 tan 3 =0.0008 ~c' c = 9.51 tan 3=0.0008 zoisite2 ~c' a = 10.55 tan 3 = 0.0011 t tc b = 15.45 tan 3 =0.0013 ~c' c = 9.39 tan 3=0.0008 epidote ~'11 = 9.52 tan 3 = 0.0008 ~:~2 = 17.1 tan 3 =0.0009 ~c;3 = 9.37 tan 3 =0.0006 fluorapatite I ~C' a = 10.48 tan 3 = 0.0008 ~:'c = 8.72 tan 3=0.0114 fluorapatite2 ~c', = 10.40 tan 3 = 0.0010 tc'~ = 8.26 tan 3=0.0178
The deviation (A) between measured dielectric polarizabilities as determined from the Clausius-Mosotti equation and those calculated from the sum of oxide polarizabilities according to eo (mineral) = ~ eD (oxides) for vesuvianite is ~ 0.5%. The large deviations of epidote and zoisite from the additivity rule with A= +10.1 and +11.7%, respectively, are attributed to "rattling" Ca ions. The combined effects of both a large F thermal parameter and possible F-ion conductivity in fluoraparite are believed to be responsible for A = + 2-3 %. Although variation of oxygen polarizability with oxygen molar volume (Vo) is believed to affect the total polarizabilities, the variation of Vo in these Ca minerals is too small to observe the effect.