Clay research in Australia and New Zealand

The papers in this special issue of Applied ClayScience cover a diverse range of topics. With theexception of the contribution by Zhu et al., all dealwith clays of Australian and New Zealand origin, orwith clay mineralogical aspects of soil problems thatare peculiar to Australia. Nevertheless, a collection ofonly eight volunteered papers could hardly be ex-pected to reflect the research interests and activitiesof clay scientists in Australia and New Zealand, ortheir past and present contributions to clay mineral-ogy.Research on clays and clay minerals in Australiaand New Zealand has a long history. A great deal ofeffort has been expended at identifying and character-ising local materials and resources. This is especiallytrue of soil clays although work of this nature is lesscommon now than was the case some decades ago.Thus, older compilations of soil data are still usefulsources of clay mineralogical information, includingStace et al. (1968) and Norrish and Pickering (1983)for soils of Australia, and N.Z. Soil Bureau (1968) forNew Zealand soils. An examination of this informa-tion and other analytical data on soil clays shows thatthe clay minerals in Australian soils are generally verydifferent from those in New Zealand soils, reflectingthe quite distinct geological and climatic histories ofthe two neighbouring countries. The land surface ofAustralia is ancient, largely stable, and highly weath-ered, whereas that of New Zealand is relativelyyouthful, having been extensively rejuvenated inrecent times by glacial, fluvial, tectonic and volcanicprocesses.As a result, the types of clay minerals that havereceived particular attention in Australia have differedfrom those studied more often in New Zealand. Forexample, the occurrence and properties of fine-grained illites, palygorskite, and interstratified kao-lin–smectites have been extensively investigated inAustralia (Norrish and Pickering, 1983), whereasallophane (Parfitt, 1990) and halloysite (Soma et al.,1992) have attracted much attention in New Zealand.Nevertheless, it is interesting to note several importantrecent contributions on halloysite from Australia(Robertson and Eggleton, 1991; Singh et al., 1992;Norrish, 1995).Oxides, oxyhydroxides and hydroxides have alsoreceived much attention in both countries. In the latestedition of the authoritative book ‘‘Minerals in SoilEnvironments’’, edited by Dixon and Weed (1989),Australian authors were either solely or partiallyresponsible for chapters on ‘‘Iron oxides’’ (Schwert-mann and Taylor, 1989), ‘‘Manganese oxides andhydroxides’’ (McKenzie, 1989), and ‘‘Titanium andzirconium minerals’’ (Milnes and Fitzpatrick, 1989).Among this suite of minerals, ferrihydrite has pro-vided a recent focus of interest of New Zealandworkers (Childs, 1992). However, few comparativestudies have been made on the occurrence and proper-ties of these or other clay minerals in New Zealandand Australia, apart from some work on lepidocrocitein soils (Fitzpatrick et al., 1985).There has been a continuing interest in clays forindustrial uses, especially in Australia. This particulartopic is discussed by several papers in this special