Nanoparticles in groundwater of the Qujia deposit, eastern China: Prospecting significance for deep-seated ore resources

•Nanoparticlesingroundwaterwere investigated using TEM.•Nanoparticles with different contents of ore-forming elements can be grouped into three main types.•A relationship between metal-bearing nanoparticles and concealed orebodies was demonstrated.•Classification of ore-related nanoparticles was important for the detection of mineralization information.