出典:Wikipedia
出典:『Wikipedia』 (2011/02/23 19:20 UTC 版)
Alum shale (also known as alum schist and alum slate) is a variety of shale or clay slate (oil shale) containing pyrites. Decomposition of pyrite by weathering forms sulfuric acid, which acts on potash and alumina constituents to form alum, often efflorescences on the rock.