Clay Ironstone, a granular or compact admixture of the mineral siderite (ferrous carbonate) and clay. It occurs as nodules or in thin beds in various geological systems, but especially in the carboniferous strata. It frequently contains organic matter. When very highly carbonaceous, it passes into the variety called blackband ironstone. See IRON ORES.
Clay Ironstone
Chambers's Encyclopaedia, Volume 3: Catarrh to Dion, p. 284
Source scan(s): p. 0295