Millstone Grit is the name given to any of a number of coarse-grained sandstones of Carboniferous age which occur in Northern England. The name derives from its use in earlier times as a source of millstones for use principally in watermills. Geologists refer to the whole suite of rocks that encompass the individual limestone beds and the interven...
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http://en.wikipedia.org/wiki/Millstone_Grit
A sharp sandstone rock found in the UK and used for grinding flour and for for sandstone grinding wheels. ;
Found on
http://www.encyclo.co.uk/local/22188
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