TEM observations of particles in groundwater and their prospecting significance in the Bofang copper deposit, Hunan, China

Abstract Groundwater is an important medium in geochemical research due to its mobility and low elemental background values. Currently, major ion and isotopic analyses are the methods that are most commonly used to examine elemental contents. This paper aims to explore nanoparticles related to deep concealed ore bodies in the Bofang deposit through discussions on their classification and origins and ultimately to provide recommendations for prospecting. This research takes groundwater as the main medium for TEM (transmission electron microscope) observations. All particles in deep and shallow groundwater samples contain Cu, Zn, Pb, As, Fe and other metal elements that are related to the ore body. Cu-bearing particles, which are the focus of this study, comprise the following main components: Cu-bearing particles with carriers and those without carriers. These two types of particles are discussed and classified; then, individual particles are selected. Among these particles, the Cu-bearing particles that originated from concealed ore bodies comprise the following three types: 1) Cu occurring with and migrated by geochemical carriers; 2) Cu nanoparticles physically adsorbed and migrated by Fe(OH) 3 ; 3) Cu migrating as single Cu or Cu-O nanoparticles. These individual particles and the geological information they provide about the Bofang copper deposit suggest that metals that are captured by geochemical carriers in groundwater should be analyzed. Analysis of these particles, combined with analyses of other important prospecting geological data, could reduce the cost of drilling and narrow areas of interest.