  The differences on the thermal behavior (DTA-TG) of mica samples measured
before and after sonication have been studied. Sonication treatment produces
important modifications in the thermal behavior of muscovite and biotite
samples. For muscovite, it produces a broadening and decrease in temperature of
the dehydroxylation and crystallization effects, reaching a steady stage after
40 h treatment time. For biotite, the original single peak profile for the
dehydroxylation of the untreated sample is converted into a two peaks profile
after sonication, the intensity of the low temperature peak increases with
sonication time, while the intensity of the high temperature peak decreases.
The modification of the thermal behavior for sonicated samples has been
correlated to the particle size distribution effect produced by the sonication
treatment. It has been also observed that the cup tip of the sonication
equipment contaminates the samples releasing titanium of its composition
