Mineralization episodes and their concentration sites in a typical British coal

Abstract

Twenty four (24) coal samples from the eight (8) working collieries of Northumberland coalfield, England, have been studied with the view to analyzing the possible location/concentration of the mineral species in coals. The results of the study showed that their clay mineral suites dominated by kaolinitic types are disseminated products at maceral boundaries, desiccation cracks and at times fissures with no established genetic evidence. The other widespread variety of mineral occurrences, notably calcite, siderite and sometime pyrite in the coal basin and traceable to precipitates in various joints, cleats, cell voids and lumens are associated/formed during epigenetic mineralization episode (post depositional phase), when the macerals have differentiated into their various entities. More importantly, these mineral concentration appears to have been partly or wholly controlled by the semifusinite/fusinite macerals (i.e. particularly those exhibiting "Bogenstruktur") as the preferred traps and/or infills for coals. With the exception of the nodular pyrite that is said to be linked to both vitrinitic and sometimes liptinitic macerals and are traceable to syngenetic mineralization episodes, the euhedral type pyrite demonstrates a complete unique behaviour by their infill of semifusinite/fusinite macerals which suggests the timing to be of post-depositional phase.