Relationship between optical properties of sporinite and vitrinite subjected to the thermal treatment in laboratory conditions

Optical properties of sporinite (R_sr = 0.17 %) and vitrinite (R_r = 0.8 3 %) in concentrates, subjected to the action of temperature within the range of 400-600 °C and time of 1-5 h, in neutral conditions (argon), were determined. Transformation of the two constituents, is influenced rather by the increase in temperature than the time applied. Reflectance and bireflectance of sporinite and vitrinite, after heating, substantially rise (at 600 °C and 1h time: R_sr = 3.23 %; R_r = 2.83 %). The original arrangement of optical axes in sporinite is more resistant to temperature influence, and the internal structure of this maceral organised better, than in the case of vitrinite.