Thermal behavior of talc samples (from locality Puebla de Lillo, Spain) were characterized by emanation thermal analysis (ETA),
DTA and TG. The ETA, based on the measurement of radon release rate from samples, revealed a closing up of surface micro-cracks
and annealing of microstructure irregularities of the talc samples on heating in the range 200–500°C.
For ground talc sample a crystallization of non-crystalline phase formed by grinding, into orthorhombic enstatite was characterized
as a decrease of radon mobility in the range 785–825°C and by a DTA exothermal effect with the maximum at 830°C. ETA results
characterized the microstructure development of the talc samples on heating and served to evaluate their radon mobility and
transport properties on heating and cooling. Transport properties of the talc samples were evaluated by using ETA experimental
data measured during heating to 600 and 1300°C, respectively, and subsequent cooling to room temperature.