Monorthic -Kaolinite, halloysite and or fully hydroxy interlayered vermiculite (HIV) dominate the clay fraction. If smectite is present it should be at low concentrations such that it is not identifiable by appropriate mineralogical analyses (usually less than 10%). Usually the clay fraction CEC at pH 7 is < 30 meq/100g. Coarse fractions are typically siliceous (>90% quartz+resistant minerals).

Parasmectic - Biasiallitic soil material in which smectite is identified, but is not the dominant mineral, smectite content ranges from 10 to 50 percent of the clay fraction. Quartz is not the dominant mineral in the clay fraction.

Smectic - Biasiallitic soil material in which smectite is the dominant mineral in the clay fraction. Typically smectite content is more than 50 percent of the clay fraction.