Definition of "noncombustible" [noncombustible]

• That will not readily ignite and burn (adjective)

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• "MSHA official Kevin Stricklin said that, of 1,800 rock-dust samples collected from the Upper Big Branch mine, the noncombustible content in 79% of the samples was too low."
• "Coal dust can mix with the rock dust in the normal course of mine operations, but regulations require that a majority of the dust remain noncombustible."
• "Safety officials investigating the Massey Energy coal-mine explosion said most dust samples from the mine had insufficient levels of noncombustible material."