Galena - the Primary Ore of Lead

What is Lead?

Lead is a corrosion-resistant dense metal that is easily molded and shaped. The chemical symbol for lead, Pb, is an abbreviation of the Latin word plumbum, meaning soft metal. Archeological research indicates that lead has been used by humans for a variety of purposes for more than 5,000 years.

Lead is rarely found in native form in nature but it combines with other elements to form a variety of interesting and beautiful minerals. Galena, which is the dominant lead ore mineral, is blue-white in color when first uncovered but tarnishes to dull gray when exposed to air.

Related:   Galena - the Primary Ore of Lead

Ancient Uses of Lead

Water pipes that date back to the Roman Empire, glazes on prehistoric ceramics, and the cosmetic kohl, used by ancient Egyptians to darken their eyelids, are a few examples of ancient uses of lead. Today, lead, which has been mined on all continents except Antarctica, is one of the most important metals to industrialized economies.

Modern Uses of Lead

Prior to the early 1900s, lead was used in the United States primarily in ammunition, burial vault liners, ceramic glazes, leaded glass and crystal, paints or other protective coatings, pewter, and water lines and pipes. Following World War I, the demand for lead increased because of growth in the production of motorized vehicles, many of which use lead-acid batteries to start their engines. The use of lead as radiation shielding in medical analysis and video display equipment and as an additive in gasoline also contributed to an increase in the demand for lead.

By the mid-1980s, a significant shift in the uses of lead had taken place in the United States as a result of compliance with environmental regulations and the substitution of other materials for lead in no battery products, such as gasoline, paints, solders, and water systems. By the early 2000s, 88 percent of apparent U.S. lead consumption was in lead-acid batteries, which was a substantial increase from 1960 when only 30 percent of global lead consumption was in lead-acid batteries. Today, the other significant uses of lead are in ammunition, oxides in glass and ceramics, casting metals, and sheet lead.

 

Lead in the Environment

According to the U.S. Agency for Toxic Substances and Disease Registry, environmental levels of lead have increased more than 1,000-fold over the past three centuries as a result of human activity. The greatest increase took place between 1950 and 2000 and reflected the increased use of leaded gasoline worldwide. During this period, the U.S. Government established Federal regulations and made recommendations to limit lead emissions to protect public health in the United States.

Types of Lead Deposits

Research to better understand the geologic processes that form mineral deposits, including those containing lead, is an important component of the USGS Mineral Resources Program. Lead commonly occurs in mineral deposits along with other base metals, such as copper and zinc. Lead deposits are broadly classified on the basis of how they are formed. Lead is produced mainly from three types of deposits: sedimentary exhalative (Sedex), Mississippi Valley type (MVT), and volcanogenic massive sulfide (VMS).

Sedimentary Exhalative Deposits

Sedex deposits account for more than 50 percent of the world's lead resources. They are formed when metal-rich hot liquids are released into a water-filled basin (usually an ocean) or in basin sediments, which results in the precipitation of ore-bearing material within basin-floor sediments.

Mississippi Valley Deposits

MVT deposits are found throughout the world and get their name from deposits that occur in the Mississippi Valley region of the United States. The deposits are characterized by ore mineral replacement of the carbonate host rock; they are often confined to a single stratigraphic layer and extend over hundreds of square kilometers. MVT deposits were a major source of lead in the United States from the 19th century through the mid-20th century.

Volcanogenic Massive Sulfide Deposits

In contrast to Sedex and MVT deposits, VMS deposits have a clear association with submarine volcanic processes. They also can contain significant amounts of copper, gold, and silver, in addition to lead and zinc. The "black smoker" sea vents discovered during deep ocean expeditions are examples of VMS deposits being formed on the sea floor today.

Worldwide Supply of and Demand for Lead

Currently, approximately 240 mines in more than 40 countries produce lead. World mine production was estimated to be 4.1 million metric tons in 2010, and the leading producers were China, Australia, the United States, and Peru, in descending order of output. In recent years, lead was mined domestically in Alaska, Idaho, Missouri, Montana, and Washington. In addition, secondary (recycled) lead is a significant portion of the global lead supply.

World consumption of refined lead was 9.35 million metric tons in 2010. The leading refined lead consuming countries were China, the United States, and Germany. Demand for lead worldwide is expected to grow largely because of increased consumption in China, which is being driven by growth in the automobile and electric bicycle markets.

Ensuring Future Supplies of Lead

To help predict where future lead supplies might be located, USGS scientists study how and where identified lead resources are concentrated in the Earth's crust and use that knowledge to assess the likelihood that undiscovered lead resources exist. Techniques to assess mineral resource potentials have been developed and refined by the USGS to support the stewardship of Federal lands and to better evaluate mineral resource availability in a global context.

United States Lead Resources

Lead Production and Reserves Country Production Reserves USA 400 7,000 Australia 620 27,000 Bolivia 90 1,600 Canada 65 650 China 1,600 13,000 India 95 2,600 Ireland 45 600 Mexico 185 5,600 Peru 280 6,000 Poland 35 1,500 Russia 90 9,200 South Africa 50 300 Sweden 65 1,100 Other 330 4,000 Total 4,100 80,000 Data is in thousand metric tons. Data from USGS Mineral Commodity Summary, January 2011.

In the 1990s, the USGS conducted an assessment of U.S. lead resources and concluded that about as much lead remained to be found as had already been discovered. Specifically, the USGS found that 92 million metric tons of lead had been discovered and estimated that about 85 million metric tons of lead remained undiscovered in the United States.

Mineral resource assessments are dynamic. Because they provide a snapshot that reflects our best understanding of how and where resources are located, the assessments must be updated from time to time as better data become available and new concepts are developed. Current research by the USGS involves updating mineral deposit models and mineral environmental models for lead and other important nonfuel commodities and improving the techniques used to assess for concealed mineral resource potential. The results of this research will provide new information and decrease the amount of uncertainty in future mineral resource assessments.