Abstract:

Tonsteins, and less commonly bentonites and Kbentonites, are known to occur in many different coalbearing formations in the world throughout geological time, although the actual definition of tonsteins is still regarded in some cases as controversial.Leaching of the precursor volcanic ash by ground waters and organic acids in the peatforming environment would be expected to result in enrichment of some elements that were released from the ash and accumulated as minerals or organometallic compounds in the immediately adjacent coal. The occurrence of such minerals may therefore be indicative of volcanic influence during peat accumulation and coal formation. Tonsteins are thought to provide geochronological markers, with a widespread distribution that enables stratigraphic correlation. The primary minerals in tonsteins, if preserved, may also provide opportunities for absolute age determination. Some alkaline tonsteins are indicators for the discovering of rare metal ore deposits. The geochemical characteristics of tonsteins serve as indicators of magma affinities and volcanotectonic settings.

Key words: coal, tonstein, bentonite, Kbentonite, mineral, element