An effect of igneous intrusion on the structure, texture and microtexture of coal from the Sosnica coal mine, Upper Silesian Coal Basin, Poland

Two coal samples from the Sonica coal mine, Poland, were analysed in this study. One sample was the natural char collected at the contact of magmatic intrusion, and another sample was the raw coal that was pyrolised in a laboratory furnace. Temperature of pyrolysis was similar to that calculated for the intrusion. The obtained char was analysed to compare its features with those characterizing a natural char sample. Optical microscopy, transmission electron microscopy and Raman spectroscopy studies show that the char from unaltered coal is characterized by the least developed structure, texture and microtexture compared to the natural char. Hence, it can be concluded that geological pressure generated by both the intrusion and the overburden, strongly affects the process of molecular ordering that took place during the heating of coal. The textural, structural or microtextural parameters of coal cannot be used as a geo-thermometer, because they are strongly dependent not only on the temperature but also on other factors.