"Iron-mud - A type of iron-sediment. In the Rock Classification Scheme, it is one in which over 75% of the clasts are smaller than 32 µm. The grain size classes are defined in the same way as the siliciclastic sediments. British Geological Survey Research Report RR/99/03, section 5.1, table 13 and fig. 9. See also: silicate-mud."@en . . "FEMUD"@en . "stable"@en . . . "Iron-mud"@en . . "Iron-mud"@en .