Ore genesis accumulation of hematite gravels called "pisolites" which form channel-iron deposits. These are preferred because they are cheap to mine. Lead-zinc deposits are generally accompanied by silver, hosted within the lead sulfide mineral galena or within the zinc sulfide mineral sphalerite. Lead and zinc deposits are formed by discharge of deep sedimentary brine onto the sea floor (termed "sedimentary exhalative" or SEDEX), or by replacement of limestone, in skarn deposits, some associated with submarine volcanoes (called volcanogenic massive sulfide ore deposits or VMS), or in the aureole of subvolcanic intrusions of granite. The vast majority of SEDEX lead and zinc deposits
Ore Metal Exchange aims to add uranium to its list of metals on warrant. The World Bank reports that China was the top importer of ores and metals in 2005 followed by the US and Japan. DILL, H.G. (2010) "The “chessboard” classification scheme of mineral deposits: Mineralogy and geology from aluminum to zirconium," Earth-Science Reviews, Volume 100, Issue 1-4, June 2010, Pages 1-420 Ore An ore is an occurrence of rock or sediment that contains sufficient minerals with economically important elements, typically metals, that can be economically extracted from the deposit. The ores are extracted from the earth through mining; they