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.

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.