hardrocks

Noun

hardrock (countable and uncountable, plural hardrocks)

1. Rock containing ore from which minerals are extracted.
   • The federal system for "hardrocks," pursuant to the Mining Law of 1872, allows the discovery, location, and development of these minerals without payment to the federal government.1982, Project BOLD, page 64
2. Solid, nonporous rock.
   • The Western U.S. sample was separated into the recording site categories of hardrock ( i.e., crystalline rock outcrop) , intermediate ( i.e., sedimentary rock or thin alluvium) and alluvium ( i.e., thick alluvium), and average residuals were computed for each of the three subsets.1978, J. R. Murphy, L. J. O'Brien, Analysis of a Worldwide Strong Motion Data Sample to Develop an Improved Correlation Between Peak Acceleration, Seismic Intensity and Other Physical Parameters....
3. A type of concrete that contains relatively small amounts of aggregate relative to the amount of cement.
   • The tension test specimens embedded to 45 mm (1 - 3/4 inch) in hardrock concrete generally failed when the tensile limit of the anchor itself was reached.1991, International Federation for Structural Concrete, Fastenings to Reinforced Concrete and Masonry Structures, page 55
4. (slang) An unregenerate criminal; a bully boy.
   • Rules and regulations and strict security measures used to hold hardrocks in line work against men trying to learn responsibility for themselves.1959, Robert Neese, Prison Exposures, page 68