rock dust

noun

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

First recorded in 1930–35

This works because the carbonate materials in the rock dust will dissolve when it comes in contact with water.

It gathers rock dust and the wreck of every living thing, and mixes them up with snow and ice.

A cloud of rock dust rose and filled the air completely for several minutes.

Little clouds of rock-dust rose above the bear, in front of him, behind him, and below him.

This is in contrast to the gravel road, where little dependence is placed upon the bonding effect of the rock dust.

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.

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