[tooltip hint=”United States Geological Survey”]“Research aimed at better understanding geological processes in the form of mineral deposits, including zinc, is a key part of the USGS mineral resources programs. Zinc is typically found in mineral deposits alongside other base metals such as copper and lead. Zinc deposits are generally classified based on their formation processes. Zinc is primarily extracted from three types of deposits:”[/tooltip]
sedimentary exhalative (SEDEX)
Mississippi Valley type (MVT)
volcanogenic massive sulfide (VMS)
Exhalative Sedimentary Deposits
SEDEX deposits constitute more than 50% of the world’s zinc resources and form when metal-rich hydrothermal fluids are released into a water-filled basin (typically an ocean), causing the precipitation of ore materials within the sedimentary layers of the basin.
The largest lead and zinc mine in the world is the Red Dog mine in Alaska, which has been developed from SEDEX deposits
Mississippi Valley-Type (MVT) Deposits
MVT deposits are found worldwide and get their name from the deposits in the Mississippi Valley of the United States.
These deposits are characterized by the replacement of the ore within the host carbonate ore. They are often confined to a specific stratigraphic layer and can extend over hundreds of square kilometers.
MVT deposits were a primary source of zinc in the United States from the 19th century until the mid-20th century.
Volcanogenic Massive Sulfide (VMS) Deposits
“Unlike SEDEX and MVT deposits, VMS deposits are closely associated with submarine volcanic processes. They can also contain substantial amounts of copper, gold, silver, as well as lead and zinc.”
During their journey to the ocean depths, the ‘black smoker’ vents have discovered samples of modern-day VMS deposits that form on the seafloor.
Global Zinc Supply and Demand
In 2009, zinc was mined in six different countries. However, the United States imported 76% of its refined zinc, primarily from Canada, Mexico, Kazakhstan, and South Korea, in descending order, to meet domestic demand. Global zinc consumption remained stable in 2008, while consumption in emerging markets (such as China, Brazil, and India) increased, offsetting the decline in consumption in Europe and the United States, according to data from the International Lead and Zinc Study Group.
Although many elements can serve as substitutes for zinc in chemicals, electronics, and pigment applications, the demand for galvanized zinc products has remained strong, especially in regions where significant infrastructure projects are under development. The substantial increase in both zinc production (supply) and consumption (demand) over the past 35 years globally reflects strong demand in sectors such as transportation and communications for items like vehicle bodies, highway barriers, and galvanized structures. This highlights the importance of ensuring a steady zinc supply for the future and aids in forecasting where future zinc resources might be located. As a result, USGS scientists have been motivated to study and explore where and how identified zinc resources are concentrated in the Earth’s crust, while also using this knowledge to assess the potential for undiscovered zinc resources. The USGS’s mineral resource potential assessment methods, originally developed to support monitoring of federal lands and available mineral resources, have now been adapted for global use.
In 1990, the United States Geological Survey (USGS) conducted an assessment of U.S. zinc resources and concluded that twice the amount of zinc currently discovered is expected to be found.
The USGS specifically found that less than 100 million tons of zinc had been discovered in the United States and estimated that approximately 210 million tons of zinc remained undiscovered.
Mineral resource assessments are dynamic and must be regularly updated, as they provide a snapshot at a specific moment in time, reflecting the current level of knowledge while new data and concepts continue to emerge. For example, during geological research in the late 1960s, USGS geologists noted widespread iron oxide staining in the drainage areas of the Western Brooks Range, Alaska.
Red Dog Lead and Zinc Deposits
Continued studies led to the discovery of the Red Dog lead-zinc deposits. In the late 1990s, after a decade of exploration and development, the Red Dog mine in Alaska began production and has since made a significant contribution to the global zinc supply. Further research in the region also provided a deeper understanding of the complex factors controlling the formation of Red Dog and other similar deposits, establishing a foundation for evaluating comparable deposits in similar geological settings worldwide.
Other recent research by the USGS includes updating models of mineral deposits, environmental models, zinc resources, other critical non-fuel commodities, and enhancing techniques for assessing the potential of undiscovered mineral resources. The findings from this research provide valuable new information and help reduce uncertainties in future mineral resource assessments.
Historical Applications of Zinc
Zinc was used for centuries before it was identified as an element, primarily for producing brass (an alloy of zinc and copper) and for medicinal purposes. Zinc metal and zinc oxide were produced in India between the 11th and 14th centuries, and in China by the 17th century. However, the discovery of pure zinc is credited to the German chemist Andreas Marggraf, who first isolated the element in 1746.
Sphalerite: The Primary Ore of Zinc
Sphalerite (zinc sulfide) is the primary ore from which most of the world’s zinc is produced, but several other minerals that do not contain sulfide also contain zinc as a major component. Much of the early zinc production came from non-sulfide deposits; however, as these resources were exhausted, production shifted to sulfide deposits. Over the past 30 years, advances in extraction and smelting technologies have led to the discovery of non-sulfide zinc deposits.
Refined Zinc Metal
Refined zinc metal has a bluish-white color in its pure form and is hard and brittle at most temperatures, with relatively low melting and boiling points. Zinc alloys readily with other metals and is chemically active.
In the presence of air, zinc forms a thin gray oxide layer (patina) that prevents further oxidation (corrosion) of the metal. This corrosion resistance is one of the key characteristics that make zinc valuable in various applications.
Current Applications of Zinc
Zinc is currently the fourth most widely used metal in the world, after iron, aluminum, and copper,
due to its strong corrosion resistance and good compatibility with other metals.
As a result, about half of the zinc produced is used in galvanizing, a process where thin layers of zinc are applied to iron or steel to prevent corrosion.
Another major application of zinc is in alloys, where it combines with copper (as brass) and other metals to create materials used in automobiles, electrical components, and household appliances.
The third major application of zinc is in the production of zinc oxide, the most important zinc chemical by production volume, which is used in the manufacture of rubber and as a skin protection ointment.
Zinc is vital for health. This element is necessary for the proper growth of humans, animals, and plants. The body of an adult contains 2 to 3 grams of zinc, which is essential for the proper functioning of enzymes and the immune system. It also plays an important role in taste, smell, and wound healing. Only small amounts of zinc are found in various foods, such as shellfish, beef, and peanuts.
Zinc Applications
A Metal Crucial for Corrosion Prevention
Published by the United States Geological Survey (USGS)
Translator: Shadi Jamili
