zeolite

Any of the hydrous aluminium silicates, also containing sodium, calcium, barium, strontium, or potassium, chiefly found in igneous rocks and characterized by a ready loss or gain of water. Zeolites are used as ‘molecular sieves’ to separate mixtures because they are capable of selective absorption. They have a high ion-exchange capacity and can be used to separate petrol, benzene, and toluene from low-grade raw materials, such as coal and methanol.