Definition of "chalkstone" []

• See tophus. (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.

• "Extrication required amputation — Mr. Ralston 's left-handed severing of his right forearm, which was pinned between a chalkstone boulder and the canyon wall."
• "The building is constructed of basalt and chalkstone and made use of elements from an earlier structure on the site."
• "And about 50 meters into the canyon at this narrow section, I encountered a place where I was standing on top of a chalkstone with about a ten-foot elevation drop."