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On Tue, 13 Dec 2005 13:33:19 +0100, Robert Waterhouse <[log in to unmask]> wrote: >Dear List, >Can anyone tell me how stamps were used in copper dressing? They are generally associated with tin rather than copper in Devon and Cornwall, but I've just come across a reference to a stamping house at Wheal Crebor, West Devon, in 1811. The mine is not known to have produced tin (other than occasional small parcels) and was primarily copper, with some arsenic later in the C19. Strangely, the known crusher house at Crebor only seems to have had a 16ft wheel, while the probable stamps had a much bigger, perhaps 30ft wheel. Its normally the other way round isn't it? Unfortunately we can't compare the buildings as both have disappeared without trace. >Robert Waterhouse >========================================================================= Stamps were generally used for crushing finer grain, disseminated, ores, where crushing rolls would not reduce particle size sufficiently to allow effective dressing. Prior to the introduction of the crushing roll (at Crowndale or on Alston Moor?) coarser ores were broken and dressed by hand, & finer ores treated in stamps. At Crebor the produce (grade) of ore (concentrate) for all parcels is known at this time, so some idea of how each parcel was dressed could be guessed at - unfortunately the smelters' accounts (which record features such as "stamped ore", "burnt ore", etc may not survive for this period - I have only seen them for c1840 onwards. Generally stamped ore (presumably dressed on buddles etc)would be lower grade than ore crushed & jigged or hand dressed. There are records c1750 re copper stamps in the Porthtowan area, some of the workers later moving to the Tavistock area. Incidently I think the Impham stamps a site well worth proper archaeological investigation. These certainly existed before c1700 & were probably originally set up to treat ore from the quite large tin openworks (perhaps 15th-16thC) above the site, but estate accounts refer to them being taken up again in the 18thC, when there were numerous short-lived minor workings in the area, both tin and copper. This long history & perhaps use for both tin & copper dressing makes them potentially a very important site. Alasdair Neill.