Soils more important rock formation

In simple adsorption from aqueous solution, Hg has features in contrast and in common with the base metals. The hydroxy-cation is the active species in the model for heavy-metal adsorption and this also appears to be true for Hg. However, in contrast with Cu, Pb and Zn, the adsorption is less efficient and is strongly inhibited by the formation of halide complexes, as has been shown by Forbes et al. (1974) (Fig. 12-1). These authors also demonstrate that the adsorption of Hg to goethite is effective at pH as low as 4, allowing it to be trapped subsequent to sulphide oxidation. Whilst many minerals in weathered rocks and soils may each adsorb Hg, the relative efficiency of the hydrous iron oxides (Andersson, 1979) implies that these phases will be the dominant host in most exploration samples. However, the soil organic matter is also of importance and, although the association with Hg has been described as adsorption, it seems more... 

The raw materials for cement manufacture which are the subject of geological exploration are mainly limestones and clays. In the geological sense both are sedimentary rocks which may occur as hard or dense material (commonly known as "rock") or softer soil deposits. They may be of any geological age. Limestones mostly occur in the form of rock, sometimes constituting whole mountainous formations. In Europe, more particularly the Devonian granular limestones, the Jurassic and Triassic limestones of the Alpine region and the Cretaceous limestone deposits are of importance. 

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