rock dust

noun

a crushed limestone sprayed on surfaces in mines to make coal dust incombustible in case of a gas explosion.

Origin of rock dust

First recorded in 1930–35

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

This works because the carbonate materials in the rock dust will dissolve when it comes in contact with water.
Volcanoes could be our fiery allies in the fight against carbon emissions | Angely Mercado | August 26, 2021 | Popular-Science
It gathers rock dust and the wreck of every living thing, and mixes them up with snow and ice.
Over the Rocky Mountains to Alaska | Charles Warren Stoddard
A cloud of rock dust rose and filled the air completely for several minutes.
Watched by Wild Animals | Enos A. Mills
Little clouds of rock-dust rose above the bear, in front of him, behind him, and below him.
Tenting To-night | Mary Roberts Rinehart
This is in contrast to the gravel road, where little dependence is placed upon the bonding effect of the rock dust.
American Rural Highways | T. R. Agg

Then, once in a great while, a third kind will descendthe accumulated snow and ice and rock dust of maybe half a century or more.
Boy Scouts in Glacier Park | Walter Prichard Eaton

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