The endothermic peak observed for sample E-1 (containing about 70% actinolite) around 1220 °C resulted from deformation of the crystal structure of actinolite (Taboadela & Aleixandre Ferrandis 1957).
The highest mass loss occurred in sample
E-3, which probably resulted from calcite content. Mass
loss (~5 wt.%) occurred in sample E-3 between the
temperatures of approximately 650 and 800 °C, and this
resulted from CO2
gas that was removed from the structure
after the thermal decomposition of calcite. Consistent with
this, on the DTA curve of the same sample, endothermic
peaks from 760 to 895 °C confirm this situation. Similar
results were obtained in thermal analyses performed using
various solids containing pure calcite (Hristova & Jancev
2003; Hojamberdiev et al. 2008). The total mass loss values
of the samples (Figure 7b) are corroborated by the loss on
ignition yielded by the chemical analysis (Table 2).