Board Thread:Questions and Answers/@comment-7463332-20130725231957/@comment-5627887-20130726172941

There's another kind of sludge that looks like a darker version of clay, that comes from washing Dirty Ore Gravel from the Factorization mod. It can be smelted to produce clay, much like MFR Sludge is processed to produce Clay, however the Factorization Sludge won't produce Dirt, Sand and Soul Sand like the MFR one will.