Illite Good Absorbent Oil Control Illite opis Illite is a mineral-sourced natural thickener that also has good absorbent properties and is sometimes referred to as French green clay. Illite has a stronger ability to calm skin irritated by influencing factors in skin that can lead to health issues. Interestingly, it's not as absorbent as many other clays (kaolin being one) which is why it's rarely used as the sole absorbent ingredient in products for oily or blemish-prone skin.