Petrographic examination of low-rank coals from Saskatchewan and British Columbia, Canada, including reflected and fluorescent light microscopy, SEM, and laboratory oxidation procedures

Abstract

The response to oxidation of eight coals of lignite and subbituminous rank from Saskatchewan and Hat Creek, British Columbia, was studied by means of maceral distribution, fluorescence, and scanning electron microscopy (SEM). The oxidizing agent used was Schulze's solution, with some modification of reaction time from that normally employed in palynological maceration. These eight samples were chosen to represent different macroscopically described lithotypes. Maceral analysis indicates that the huminite macerals behave differently when oxidized. Densinite seems to be the most susceptible to destruction, along with gelinite. Humotelinite (eu-ulminite and texto-ulminite) is more resistant and in four of the eight samples shows a slight increase in concentration. Oxidation increases the relative content of liptinite along with some of the inertinite macerals (fusinite and semifusinite). Among the liptinite macerals resinite appears to be preferentially concentrated, suggesting that the modified oxidation procedure is not rigorous enough to enrich spore and pollen concentrations. The Hat Creek samples showed a variety of resinites that could be differentiated into four types under fluorescence conditions by comparison of colour, by wavelength of maximum fluorescence intensity, and by different red/green quotients. The SEM provides a technique not normally used to examine the morphological features of macerals. Many of these features are enhanced by the employment of this technique, and its use with oxidation residues extends our ability to observe the microscopic properties of macerals.