Lead

Galena

Galena is the most common mineral from which lead is extracted. The chemical formula for Galena, Pb S is made up of Pb (lead) and S (sulfur). Neither element has been given a subscript (a number appearing after and partly below the line) which indicates that the atoms of these two elements are in equal balance, i.e. for every atom of Pb their is one atom of S. Because Galena is composed of a metal atom and the non metal atom sulfur it is part of the mineral classification called Sulphides.

Characteristics

Crystal Structure: Cubic (001) highly perfect and easy. The atoms of Pb and S are arranged in layers and alternate like the squares of a checker board, the cubic form results from the checkerboards (layers) being stacked one above the other. This form is illustrated in the picture above.
Tenacity: Brittle
Hardness: 2.5
Density: 7.58
Color and Streak: Lead-gray
Luster: Metallic opaque

Occurrence

Galena is one of the most important lead minerals in the earth's crust. It occurs in many types of deposits: sedimentary rocks, hydrothermal veins, and also pegmatites. In deposits of low temperature origin Galena occurs as irregular masses in solution cavities and in brecciated zones in Limestone.

Extensive hydrothermal vein deposits containing Galena are also important as a source of lead; in addition, these deposits may contain significant silver values. In veins of intermediate temperature origin, Galena, Sphalerite, Chalcopyrite, Pyrite, Tetrahedrite and Silver minerals occur with Quartz, Barite or Fluorite and Siderite. In veins and replacement deposits of high temperature origin, the sulphides are found with Feldspar, Garnet, Rhodonite or with Garnet, Diopside, Actinolite and Biotite. Galena is also found in deposits of contact metamorphic origin. One of Retread Resources' major projects, in 1998 was to outline a sulfide bearing deposit of Silver, Galena and Sphalerite (zinc) occurring in replacement bodies of rhodochrositic marble in the Cassiar region of northern British Columbia.

Production and use

Lead is mined in over 45 countries The five largest producers are, respectively: Australia, China, United States, Peru and Canada, and they account for 67% of world production. In 1998, the world production was about 6.75 million tonnes. The Current Average Price (October 1999) for refined Lead is about US $ 500/tonne (metric ton). Lead is one metal that is both widely used and commonly recycled, such as in automobile batteries.

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