Barbara Bielowicz

Petrographic composition of lignite from the Szczerców deposit, Polish Lowlands

Abstract Macroscopic and microscopic composition of lignite from the Szczerców deposit belonging to the Bełchatów Lignite Mine (Polish Lowlands) has been examined. The macroscopic composition was determined according to the newest lithological classification of humic coal. On this basis, it has been shown that the main lithotypes occurring in the Szczerców deposit are the detritic and xylodetritic lignites. The petrographic composition of the investigated lignite was determined microscopically for 11 samples. The examined lignite is predominantly composed of macerals from the huminite group. It is in the range from 75.2 to 86%, including atrinite (23.1–40.7%, averaging 28.9%) and densinite (18.2–41.4 %, averaging 24.9%). It also demonstrated that the statistical variability of the macerals content from the huminite group in the studied lignite is very weak in all samples. In addition, the random reflectance of ulminite was measured traditionally. The results, ranging from 0.247 to 0.282%, with the maximum permissible standard deviation < 0.07, were achieved for all analysed lignite samples.

Petrographic Composition of Lignite from the Lake Somerville Spillway (East-central Texas)

In the presented paper, the macroscopic and microscopic composition of lignite from Lake Somerville Spillway has been examined. The study area is the upper part of the Manning Formation, located north-west of Somerville in the central-eastern part of Texas. There are three exposures: NE, SW and MC (Main Central) with visible parts of late-Eocene lignite seams belonging to the Jackson Group. The Manning section is divided into four marine dominated parasequences (P1 through P4). Lignite samples outlining the P1 parasequence from the MC and NE outcrops and the argillate sample from the lower part of the P2 parasequence, NE outcrop. Macroscopic characterization was carried out based on lithological classifications of humic coal. On this basis, it has been shown that the main lithotype occurring in the deposit is detritic (matrix) coal with a high share of mineral matter. The maceral composition of coal was determined according to the ICCP guidelines. The macerals from liptinite group were determined under fluorescent light. The maceral group content analysis was performed with use of 500-600 equally spaced points on the surface of the polished sections. It has been found that the examined coal is dominated by macerals from the huminite group, with a share ranging from 20.8 to 65.3% volume, including atrinite (9.8-22.8% volume, 17.5% volume on average). In the examined coal, macerals from the inertinite group (10.1 to 44.8%), especially semifusinite (max. 13.9%), fusinite (max. 9.3%) and funginite (max. 6.3 %) are of particularly large share. In the liptinite group, particular attention was paid to the content of alginite (max. 4.5%) and bituminite (max. 1.3 %), which indicate the paralic sedimentation environment of the examined coal. Additionally, the variability of macerals and maceral groups within the exposures and levels of the P1 parasequence was examined. The last step was to compare lignite from Lake Somerville Spillway with other lignites belonging to the Jackson Group, namely Gibbons Creek and San Miguel lignite mines.