Purbeck Mineral and Mining Museum
After the closure of Eldon sidings all clay exports were via lorry. For several years the clay was carried from the mines across the A351 by trains to the "Lorry Drop". It was realised that the lorries could take the clay directly from the mines and the cost of maintaining a railway system avoided. The transhipment buildings were raised to accommodate the lorries beneath them and in the early 1970s the railway system sold partly into preservation and the rest scrapped. Use of narrow gauge railways continued underground at Norden No 6 & 7 mines until all mining operations ceased in 1999.
Ball clay
Ball clays are kaolinitic sedimentary clays that commonly consist of 20–80% kaolinite, 10–25% mica, 6–65% quartz. Localized seams in the same deposit have variations in composition, including the quantity of the major minerals, accessory minerals and carbonaceous materials such as lignite. They are fine-grained and plastic in nature, and, unlike most earthenware clays, produce a fine quality white-coloured pottery body when fired, which is the key to their popularity with potters.