Typical catalysts are sulfated oxides of titanium and zirconium or specially treated alumina or zeolites. Typical procedures entail heating aqueous solutions of alumina and silica with sodium hydroxide. Typical adsorbents are activated carbon, silica gel, alumina, resin and zeolite. They include substances such as silica, alumina, and fire clay brick refractories. Clinoptilolite is a natural zeolite composed of a microporous arrangement of silica and alumina tetrahedra. Partition HPLC has been used historically on unbonded silica or alumina supports. They are composed of silica and alumina. Bauxite is refined into alumina, which is later smelted into aluminium. These sheets are available in various materials such as alumina, zirconia and magnesia. The pozzolanic mortar used had a high content of alumina and silica. Typical supports include various kinds of carbon, alumina, and silica. This made Hydro a significant player in bauxite mining and alumina refining. Ceramics such as alumina, zirconia, and especially magnesia will tolerate the highest temperatures. These sheets are available in various materials such as alumina, zirconia, and magnesia. This method is only applicable to sintered alumina core porcelain.