# hardrock
## English
### Etymology

From hard +‎ rock.

### Noun

hardrock (countable and uncountable, plural hardrocks)
* (mining) Rock containing ore from which minerals are extracted.
** 1982, Project BOLD, page 64: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.
** 2003, Matthew. H. Salisbury, Craig. W. Harvey, Larry Matthews, “The Acoustic Properties of Ores and Host Rocks in Hardrock Terranes”, in David W. Eaton, Bernd Milkereit, Matthew Harold Salisbury, editors, Hardrock Seismic Exploration, page 9:Reflection coefficients calculated from impedance contrasts between felsic and mafic rocks and other common lithologies in hardrock terranes often exceed 6%, the estimated minimum value required to give strong reflections.
** 2009, Robin M. Nazzaro, Hardrock Mining: Information on State Royalties and Trends, page 3:In this context, you asked us to provide information on (1) which types of royalties the 12 western states assess on hardrock mining operations and (2) trends on imports and exports of hardrock minerals.
* (geology) Solid, nonporous rock.
** 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., page 3-17: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.
** 1982, Leslie Abbie, Leslie A. Abbie, James Q. Harrison, Economic Return to Investment in Irrigation in India, page 31:Its importance lies in the fact that hardrock areas cover the greater part of peninsular India. Moreover, many hardrock areas are drought-prone, making irrigation essential for reliable cropping.
** 1987, Vandana Shiva, J. Bandyopadhyay, Ecological Audit of Eucalyptus Cultivation, page 56:Being geologically characterised by shallow topsoil layers overlying the hardrocks of the Deccan, the groundwater resources in this ecozone are localised pockets of water percolating through fissures and cracks in the hardrocks.
** 2009, Graham E. Fogg, Investigation of Groundwater Flow in Foothill and Mountain Regions Using Heat Flow Measurements, page 19:There are a number of hardrock boreholes in the Tahoe Basin area that were drilled for single household water supply, for snowmaking and lodge facilities ( e.g. Heavenly Valley Resort, Northstar Resort), recreational facilities (U.S. Forest Serrvice) and for use by government agencies (Caltrans, Civilian Conservation Corp). Most hardrock wells are located at high elevation, where suitable basin-fill aquifers are not available for water supply.
* A type of concrete that contains relatively small amounts of aggregate relative to the amount of cement.
** 1991, International Federation for Structural Concrete, Fastenings to Reinforced Concrete and Masonry Structures, page 55: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.
** 1993, Better Roads - Volume 63, page 36:However, the hardrock concrete at the ends of the bridge is badly cracked and deteriorated.
** 2007, David Easton, Cynthia Wright, The Rammed Earth House, page 208:Unlike hardrock concrete, which is very dense, soil cement creates a “softer” floor.
* (prison slang) An unregenerate criminal; a bully boy.
** 1959, Robert Neese, Prison Exposures, page 68:Rules and regulations and strict security measures used to hold hardrocks in line work against men trying to learn responsibility for themselves.
** 1995, Natasha Tarpley, Testimony: Young African-Americans on Self-discovery and Black Identity, page 170:As he looked around his eyes met those of two hardrocks, who sat on top of one of the speakers.
** 2011, Jeff Chang, Can't Stop Won't Stop: A History of the Hip-Hop Generation, page liv:Across the Bronx River, a small band of hardrocks at the Bronxdale Houses called the Savage Seven grew and adopted a new name, the Black Spades.