Definition of "buhrstone" []

• A tough, silicified limestone formerly used to make millstones. It is typified by the presence of multiple cavities that originally housed fossilized shells. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "The quartzite in Montgomery, takes the form of a buhrstone, which is supposed to be valuable for the manufacture of mill stones."
• "On Laurel River in Madison is a peculiar cherty splintered whitish quartz rock which Mr. George Gehagan has manufactured into millstones, which are described as nearly equal in performance to the French buhrstone."
• "It is like the buhrstone of Paris, very tough and hard, and perfectly adapted to grinding wheat."