IDENTIFICATION OF MN-OXIDE MINERALS IN SOME SOILS FROM DEVON, UK, ANDTHEIR VARYING CAPACITY TO ADSORB CO AND CU

A number of Mn-oxide minerals in soils from a farm in North Devon have been tentatively identified using a combination of advanced analytica l techniques: scanning electron microscopy (SEM), scanning electron mi croprobe (SEMP), X-ray diffraction (XRD) and bulk chemical analysis by wet digestion followed by inductively-coupled plasma spectrometry (IC P). The minerals lithiophorite and hollandite are thought to occur thr oughout the study area although there is considerable geographical var iation in the proportions of minerals present. Birnessite, vernadite, romanechite, todorokite and cryptomelane may also be present, although in smaller amounts. The use of SEMP, together with a simple sorption experiment, has allowed a study of the extent of uptake of Co and Cu b y different Mn-oxide minerals. Lithiophorite appears to take up Co and Cu more effectively than hollandite within a pH range of 4-6.