TONSTEIN BAND IN THE SOUTH LANCASHIRE COALFIELD SIRS,-R. A. Eden et al. 1 refer to the discovery of several tonstein bands in the coalfields of the East Midlands. In May 1961, a 1 inch tonstein band was discovered in the upper part of the Worsley Four Feet Seam at Agecroft Colliery, Lancashire, in the course of work on the petrology of coal seams and associated measures, at the Chester Coal Survey Laboratory (now operating from Shade House, Pendlebury). Macroscopically, the band had been

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... d as an inferior dull coal. However, on microscopical examination, with oil immersion objectives, of stained polished blocks, vermicules of kaolinite, displaying the characteristic " cat's tail " structure, were clearly visible. A considerable amount of carbonaceous matter was also present, the ash content of the band being 46 per cent. Thin sections were prepared at the Sheffield Coal Survey Laboratory and it was confirmed that the band was indeed a tonstein, containing lenses of microcrystalline kaolinite in addition to the vermicules. Examination of crushed samples of the seam from the nearby Astley Green Colliery also indicated the presence of the band at the same horizon. This band may be the equivalent of that recorded in the High Main Seam of the East Midlands.