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Rock Dusting courtesy of the College of Earth and Mineral Sciences of the Pennsylvania State University Rock Dusting
(Definition of Rock dust) Pulverized limestone, dolomite, gypsum, anhydrite, shale, adobe, or other inert material, preferably light colored, 100 percent of which will pass through a sieve having 20 meshes per linear inch and 70 percent or more of which will pass through a sieve having 200 meshes per linear inch; the particles of which when wetted and dried will not cohere to form a cake which will not be dispersed into separate particles by a light blast of air; and which does not contain more than 5 percent combustible matter or more than a total of 4 percent free and combined silica (SiO2), or, where the Secretary finds that such silica concentrations are not available, which does not contain more than 5 percent of free and combined silica.

Generous applications of rock dust can prevent the propagation of coal dust explosions. The law requires that all areas of a coal mine that can be safely traveled must be kept adequately rock dusted to within 40 feet of all working faces. These are minimum requirements.

REMEMBER - The chance of propagation and risk of widespread explosion disasters in bituminous coal mines can be nearly eliminated when rock dust is applied liberally and maintained properly. However, unless rock dusting is appropriately and properly maintained, it will almost surely fail in an emergency.

This website is intended to provide operators with background information, suggested methods and uses, and links to manufacturers' available equipment types. Previous research by NIOSH and safety material developed by MSHA are also linked. Rockdusting is of extreme importance in the prevention or lessening the effect of fires and explosions in underground coal mines.


  • 2010-23789 - Emergency Temporary Standard
    Maintenance of Incombustible Content of Rock Dust in Underground Coal; Emergency Temporary Standard; public hearings; close of comment period - published 09/23/2010
  • Program Information Bulletin PIB10-18
    Accumulation of Combustible Materials and Rock Dust - Published September 21, 2010
  • Float Coal - video clip
    This video is an overview of the danger of un-neutralized coal dust in mines explosions, please use this link.
  • Equipment Types and Manufacturers

  • MSHA Rock Dust Related Information

  • NIOSH & Other Research Information

  • Some or all of the files available on this page are PDF. For more information on PDF, PDF readers and accessibility issues, please use this link.