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
Hydrothermal mineral deposit Mineral commodities can be classified as metals or non-metals. Metals refer to elements of the periodic table which include base, ferrous, minor fissionable and precious metals. On the other hand, non-metals refer to industrial minerals such as gypsum, diamonds, oil, coal and aggregate. According to many experts, deposits are scarce. Hydrothermal mineral deposits play a great role in everyday live since the production from these ore bodies makes modern industry possible. According to some authors, the hydrothermal solutions can have four origins, although any single volume of hydrothermal solution is commonly a mixture of two or more types: Ore minerals