Mineralogy, geochemistry and pyrite content of Bulgarian subbituminous coals, Pernik Basin

Abstract

The mineralogy and geochemistry of Pernik subbituminous coals (coal bed A) and some genetic peculiarities related to the mineral formation were studied. The mineral matter of the coal consists chiefly of pyrite, kaolinite, siderite, quartz and calcite. Other minerals (dolomite, ankerite, plagioclase and some sulphates) are present in minor amounts, some occurring as accessory single crystals. Pyrite is the main mineral in these coals and exhibits a large array of textures and morphology. Isolated and clustered euhedral, bacterial and inorganic framboidal, cluster-like, homogeneous and microconcretional massive, infilling and replacing anhedral, and cleat-filling and fracture-filling infiltrational pyrite types were observed. Four stages of mineralization were distinguished: pyrite-kaolinite, pyrite, pyrite-siderite and sulphate stages. The amount of pyrite present in two sections of coal bed A was determined by quantitative powder X-ray diffraction analysis. The concentrations of 37 trace elements were determined. As, Cu, Co, Ni, Zn, Pb, V Ti, Mo, Rb, Cr and Mn are typomorphic for this coal. On the basis of their relation to organic or inorganic matter, four groups of trace elements were subdivided; and on the basis of cluster analysis four associations were differentiated.

Geological Controls on Mineralogy and Geochemistry of the Permian and Jurassic Coals in the Shanbei Coalfield, Shaanxi Province, North China

“…Pyrite is only detected in the Jurassic coals and occurs as framboidal euhedral crystals within organic matter ( Figure 3D,F). Here, the framboidal pyrite with a relatively uniform distribution closely to one another is different with the bacteriogenic framboidal pyrite which occurs as separated globules described by Kostava et al [54], indicating authigenic origin during syn-depositional or early diagenetic stage. Galena, containing Cu and Hg, occurs as crystals included within the kaolinite matrix ( Figure 7B-D), indicating an authigenic origin.…”

Enrichment of U-Re-V-Cr-Se and rare earth elements in the Late Permian coals of the Moxinpo Coalfield, Chongqing, China: Genetic implications from geochemical and mineralogical data

“…7E, F) probably of bacteriogenic origin (cf. Kostava et al, 1996), or is distributed along the bedding planes. The modes of occurrence of pyrite in the coal suggest that it is of syngenetic or early-diagenetic origin.…”

Concentrations and modes of occurrence of trace elements in the Late Permian coals from the Puan Coalfield, southwestern Guizhou, China

“…4), cell-filling (Fig. 5), and nodular forms, indicating that pyrites in the coals are being of syngenetic or early diagenetic origin (Chou, 1997;Dai, Hou, Ren, & Tang, 2003a;Kostova, Petrov, & Kortenski, 1996).…”