| | Re: Laterite instead of clay
Laterite is a type of clay, formed in tropical regions where most of the mineral nutrients are leached out by rainfall. Typically, laterite has firm, solid structure like soft rock or gravel, and is the major (only?) ingredient in SeaChem's Flourite.
It shares a high CEC with other clays, but not the fine particles of the pottery clay recommended for MTS. I don't know if this is important or not. I've mixed it with MTS and used it as a cap for MTS with good results.