Clay desiccants are made from montmorillonite clay, which has a special affinity for moisture. The montmorillonite clay is composed of magnesium aluminum silicate, a naturally occurring mineral. After mining, it is purified, reduced to granules and subjected to a controlled dehydration process to increase its sorbent porosity. It recharges easily and does not swell as it absorbs water vapor. It works well at low and room temperatures, but has a low ceiling temperature. At 120º F, it will begin to shed the moisture it has absorbed. It is in the shape of small gray pellets. These absorb approximately 25% of its weight in water vapor at 77º F and 40% relative humidity. This is used for commercial and industrial purposes.