ABSTRACT
Soil mineral materials are to a large extent of two types, crystalline and ‘amorphous’, in their mineral structures. Amorphous materials are bound in normal chemical manners, usually by oxygen and metal covalent bonding, as are found in geological crystalline structures. In the case of amorphous solid materials in soils, most of the surfaces have residual ionic sites of either negative or positive charge which are distributed over the surface of the particles. Minerals, organic matter, their associations together and microaggregates are all highly heterogeneous both within soils and between soils. In the Hawaiian Islands, organic matter has resulted across the island chain from the growth and decomposition of a common suite of plants, while minerals show a development with time that reflects the volcanic history of the island chain. Organic material in soils generally combines with mineral soil clay particles, silicates and oxides.
