burrstone

from The Collaborative International Dictionary of English v.0.48
Buhrstone \Buhr"stone`\, n. [OE. bur a whetstone for scythes.]
   (Min.)
   A cellular, flinty rock, used for mill stones. [Written also
   {burrstone}.]
   [1913 Webster]
from The Collaborative International Dictionary of English v.0.48
Burrstone \Burr"stone`\, n.
   See {Buhrstone}.
   [1913 Webster]
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