Definition of rock flour in US English:

rock flour


  • Finely powdered rock formed by glacial or other erosion.

    • ‘Much quick clay does not consist of true clay minerals but rather of glacial rock flour: clay-sized particles of quartz and feldspar produced by glacial abrasion of bedrock.’
    • ‘Electron microscope examinations of undisturbed samples reveal soil diagenesis and a high percentage of rock flour in the clay fraction.’
    • ‘Unless it's required to pulverize all the coarse material, normally only a portion is taken to the next stage and pulped (ground to rock flour) using a special tungsten carbide mill.’