burnt shale

noun

1. carbonaceous shale formed by destructive distillation of oil shale or by spontaneous combustion of shale after it has been some years in a tip: sometimes used in road making

Example Sentences

Of these, oyster or marine shells, burnt shale, and slag are most common.

From Project Gutenberg

Fifty tons of this burnt shale are required to make one ton of alum.

From Project Gutenberg