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buhrstone or burrstone or burstone (BUR-stohn) - n., a tough, silicified limestone formerly used to make millstones; a millstone made with it.
Silicified means impregnated with silica, essentially the softer lime particles have been bound together with quartz or flint or similar harder material. The bu(h)r(r) in this case is burr, as in a rough edge on something that has been cut -- buhrstone typically has multiple cavities that originally housed fossilized shells, and the edges of these cavities make for good cutters for grinding grain.
---L.
Silicified means impregnated with silica, essentially the softer lime particles have been bound together with quartz or flint or similar harder material. The bu(h)r(r) in this case is burr, as in a rough edge on something that has been cut -- buhrstone typically has multiple cavities that originally housed fossilized shells, and the edges of these cavities make for good cutters for grinding grain.
---L.
