Ironstone: Mineral information, data and localities.
The term is customarily applied to a hard, coarsely banded or nonbanded, and noncherty sedimentary rock of postPrecambrian age, in contrast with banded iron formation. The iron minerals may be oxides ( limonite, hematite, magnetite ), carbonate ( siderite ), or silie (chamosite); most ironstones containing iron oxides or chamosite are ...