Lead and Zinc

Lead and zinc ores are usually found together with gold and silver. A lead-zinc ore may also contain lead sulfide, zinc sulfide, iron sulfide, iron carbonate, and quartz. When zinc and lead sulfides are present in profitable amounts they are regarded as ore minerals. The remaining rock and minerals are called gangue.

Forms of Lead and Zinc Ore

The two principal minerals containing lead and zinc are galena and sphalerite. These two minerals are frequently found together along with other sulfide minerals, but one or the other may be predominant. Galena may contain small amounts of impurities including the precious metal silver, usually in the form of a sulfide. When silver is present in sufficient quantities, galena is regarded as a silver ore and called argentiferous galena. Sphalerite is zinc sulfide, but may contain iron. Black sphalerite may contain as much as 18 percent iron.

Lead Ore

The lead produced from lead ore is a soft, flexible and ductile metal. It is bluish-white, very dense, and has a low melting point. Lead is found in veins and masses in limestone and dolomite. It is also found with deposits of other metals, such as zinc, silver, copper, and gold. Lead is essentially a co-product of zinc mining or a byproduct of copper and/or gold and silver mining. Complex ores are also the source of byproduct metals such as bismuth, antimony, silver, copper, and gold. The most common lead-ore mineral is galena, or lead sulfide (PbS). Another ore mineral in which lead is found combined with sulfur is anglesite or lead sulfate (PbSO4). Cerussite (PbCO3) is a mineral that is a carbonate of lead. All three of these ores are found in the United States, which is one of the chief lead-mining countries.

Zinc Ore

Zinc is a shiny, bluish-white metal. Zinc metal is never found pure in nature. Zinc minerals are generally associated with other metal minerals, the most common associations in ores being zinclead, lead-zinc, zinc-copper, copper-zinc, zinc-silver, or zinc only. Zinc also occurs in combination with sulfur in a mineral called zinc blende or sphalerite (ZnS). The primary source of zinc is from sphalerite, which provides about 90 percent of zinc produced today. Other zinccontaining minerals include hemimorphite, hydrozincite, calamine, franklinite, smithsonite, willemite, and zincite. Zinc ore is mined in about 50 countries, with approximately one-half the total coming from Australia, Canada, Peru, and the USSR.