Definition of "rottenstone" []

• A soft decomposed limestone, used in powder form as a polishing material. (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.

• "So I mixed a slurry of rottenstone pumice and oil and laid it in the receiver rails with a Q-tip and began hand cycling the bolt."
• "Abrasives are also used by themselves—rottenstone, whiting, and pumice, for example."
• "The smoothing is done with a lead lap and fine emery, and the polishing may be accomplished by means of a lead lap, whose surface is hacked and supplied with rottenstone and water."