or buhr·stone, burr·stone
any of various siliceous rocks used for millstones.
a millstone of such material.
Origin of burstone
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
Examples from the Web for burstone
Historical Examples of burstone
With the march of improvement, burstone mills went into the discard.All About Coffee
William H. Ukers
Rynd, rind, n. in a burstone mill, the iron which supports the upper stone.
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012