ALUM SHALE


Meaning of ALUM SHALE in English

noun

or alum slate also alum schist

: a shale or clay slate originally containing pyrite and after weathering containing aluminum sulfate formed by the action of sulfuric acid from the decomposition of the pyrite on the aluminous materials of the rock

Webster's New International English Dictionary.      Новый международный словарь английского языка Webster.