Assessment of Placer Ilmenite: A Case Study from Chavara Deposit Kerala State

Abstract

Iron and titanium contents of over thirty seven samples of ilmenites from eight cross - sections of Chavara deposit stretchig about 22 Km in the coastal zone have been determined by standard wet chemical methods. Based on ferrous - ferric and Ti/(Ti+Fe) ratios, the intensity of alteration suffered by ilmenite could be studied. It is understood that a geochemical boundary exists in the southern portion of the deposit. The generated data suggest that Chavara ilmenite correponds to an alteration stage bordering between hydrated ilmenite and peudorutile of Frost et. el., 1983. It further reveals that the ilmenite alteration progressively increases from the western margin of the deposit towards east. From the systematic conpositional analysis, it is also obvious that the Chavara depost, in general, shows a uniform compositional behaviour. This point out that the deposit has originated from a pile of ancient sediments and suffered a specific degree of weathering in total. The variation noticed in thye MgO content of ilmenite samples can either be due to the differential geikelitic substitution in the primary crystals or due to the differential leaching which took place later in the ilmenite grains. The powder X-ray diffraction studies have shown the co-existence of ilmenite, pseudorutile and rutile phases in most of the saples sudied. TGS experiments on some samples have explained the relationship between the weight change and iron content on heating the samples. SEM observations have revealed the nature of alteration in ilmenites.