The ability of fluids to pass through an earth material, typically depending on the connectedness of pore space in the material.
This category is also used for soil permeability.
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Frac sand in the United States: a geological and industry overview

Discusses the physical properties of frac sand, its geologic origin and formation contributing processes, its use in industry, consumption history and a global outlook. US / Canadian producers are detailed and potential other sources delineated in a GIS