Abstract:

Heavy mineral placers are naturally detached mineral grains (or mineral association) produced by natural weathering, erosion, transportation and deposition processes. Because heavy mineral placers can preserve large amount of genetic information on minerals, such as color, morphology, chemical composition, physical feature and mineral association, it can be utilized for back tracing the original ore bodies or for mineral exploration. Hence an easy and simple method, called natural heavy mineral placer survey, for ore exploration is gradually developed. In this article, based on the survey data, we summarized the mineral types, occurring frequency and distribution characteristics of heavy mineral placers, studied mineral association features of the heavy placers and their genetic mineralogical characteristics, and analyzed the relict of the original ore body, possible transporting distances and typomorphic indicating mineral association. We also discussed the significance in ore prospecting potential when genetic mineral characteristics of natural heavy mineral placer are used. The color, morphology and texture of heavy mineral placer still clearly retain the original typomorphic information as they are inheritable factors corresponding closely to the characteristics of the source host rocks. The placer minerals can be divided into two parts: the residual original heavy minerals including common silica, access and ore minerals, and the newly formed ones during erosion and transportation, including cuprite and malachite, reflecting both the lithology in the source area and the present formation condition. The placer mineral association is mostly inherited from primitive paragenetic mineral assemblages, therefore it can provide information on the mineralization potential. The grain features such as roundness and boundary smoothness reflect placer transport distance, they are favorable properties for identifying the responsible host rocks in the source area to guide mineral exploration.

Key words: natural mineral placer, genetic mineralogy, ore exploration method, application, prospect analysis