Room-temperature Mossbauer spectra were recorded for sand samples from two locations in
Kuwait which were prepared from bulk samples by separation according to colour or grain size.
Peaks of Lorentzian shape were fitted to the measured absorption envelopes by a least square
method. Five absorption doublets were observed in the spectra of the green colour sample; on
the basis of extracted values of isomer shifts and quadrupole splittings two major iron
compounds. namely, actinolite and epidote werc identified. Seven absorption doublets were
observed in the spectra of the bulk samples; the extracted values of isomer shifts and quadrupole
splittings led to the identification of three major iron-bearing phases, namely, hornblende,
ilmenite and magnetite. Analysis of spectra for various grain size samples confirmed previous
findings that iron-bearing phases are only abundant in fine grain sizes of less than 88pm and
that this abundance increases with decreasing grain size. The Fe+/Fe3+ ratio of hornblende
and ilmenite was found to be 1.86 and 1.7, respectively. The same values were obtained, within
experimental error, from thc spectra of the various grain size samples.
Combining the present Mossbaucr results with new electron probe microanalysis performed
on similar samples in the same laboratory, thc following formulas were obtained for
the iron-bearing compounds in the samples studied:
Hornblende Ca,.,, Na,.54K,.,,(Mg3.,, ~ei.:, Fei ~3Ti0.27AIOAhllS ,)2 Si6.88022(OH)2;
Ilmenite (Fe;.:, Fel.:, Mn,,,V ,,, )Ti,.,,03;
Actinolite Ca2,,Na,,,K,,,(Mg,,,Fe~~ Fe~~7Ti,,,AI,4,)AIo4Si,,0 2,(OH);
Epidote Ca, ,,N aUlK2 O.,,M h.,, Ti,.,, V,.,, (F~;:,AI, ,,)OH Si,O, SiO,.