Allophane is an amorphous to poorly crystalline hydrous aluminium silicate clay mineraloid. Sulfates can be subdivided into anhydrous and hydrous minerals. This is a soft clay-like material occurring naturally as an impure hydrous aluminium silicate. These rocks contain hydrous minerals biotite and hornblende partially resorbed in magmatic process. Dissolution is also different for anhydrous and hydrous forms of a drug. Fe is in oxides, hydrous, anhydrous, and in glauconites. It is a hydrous alumino-silicate. Ikaite, a hydrous calcium carbonate, can be associated with oxidizing methane at cold seeps. Bog iron, like other hydrous iron oxides, has a specific affinity for heavy metals. The subducting basalt and sediment are normally rich in hydrous minerals and clays. It has two forms&colon; "dry" (anhydrous); and "hydrated" (hydrous). Fuel bio-oil can also be produced by hydrous pyrolysis. This is known by several terms, including direct hydrothermal liquefaction, and hydrous pyrolysis. This leads to significant extraction of hydrous felsic melts from granulite-facies resitites. Water is also bound in hydrous minerals, especially clays and opal.