12.6: Mineral Resources

Figure \(\PageIndex{1}\): Gold-bearing quartz vein from California.

Mineral resources, while principally nonrenewable, are generally placed in two main categories: metallic (containing metals) or nonmetallic (containing other useful materials). Metallic minerals are those from which valuable metals (e.g. iron, copper) can be extracted for commercial use. Metals that are considered geochemically abundant occur at crustal abundances of 0.1 percent or more (e.g. iron, aluminum, manganese, magnesium, titanium). Metals that are considered geochemically scarce occur at crustal abundances of less than 0.1 percent (e.g. nickel, copper, zinc, platinum metals). Some important metallic minerals are: hematite (a source of iron), bauxite (a source of aluminum), sphalerite (a source of zinc) and galena (a source of lead). Metallic minerals occasionally but rarely occur as a single element (e.g. native gold or copper). Most mining is focused on metallic minerals. A significant part of the advancement of human society has been developing the knowledge and technologies that yielded metal from the Earth and allowed the machines, buildings, and monetary systems that dominate our world today. The location and recovery of these metals have been a key facet of the study of geology since its inception.

Minerals. SemiletovaOlga, CC BY-SA 4.0 <https://creativecommons.org/licenses/by-sa/4.0>, via Wikimedia Commons

While receiving much less attention, nonmetallic mineral resources (also known as industrial minerals) are just as vital to ancient and modern society as metallic minerals. Nonmetallic minerals are valuable, not for the metals they contain, but for their properties as chemical compounds. Because they are commonly used in industry, they are also often referred to as industrial minerals. They are classified according to their use. The most basic of these is building stone. Limestone, travertine, granite, slate, and marble are common building stones and have been quarried for centuries (Figure \(\PageIndex{2}\)). Some industrial minerals are also used for building materials (e.g. gypsum for plaster and kaolin for bricks). Some industrial minerals are used as sources of important chemicals (e.g. halite for sodium chloride and borax for borates). For everything made out of concrete or asphalt, we need sand and gravel. To make the cement that holds concrete together, we also need limestone. Others are used for making fertilizers (e.g. apatite for phosphate and sylvite for potassium). Still others are used as abrasives (e.g. diamond and corrundum). For the glass in our computer screens and for glass-sided buildings, we need silica sand plus sodium oxide (Na₂O), sodium carbonate (Na₂CO₃), and calcium oxide (CaO). For a wide range of applications (e.g., ceramics and many industrial processes), we also need various types of clay. Some nonmetallic mineral resources are not mineral specific; nearly any rock or mineral can be used. This is generally called aggregate and is used in concrete, roads, and foundations. Gravel is one of the more common aggregates. Quarried rock is also used in some applications where rounded gravel isn’t suitable, such as the ballast (road bed) for railways, where crushed angular rock is needed.

Figure \(\PageIndex{2}\): Carrara marble quarry in Italy, source to famous sculptures like Michelangelo’s David.

Mineral Deposits

Minerals are everywhere around us. For example, the ocean is estimated to contain more than 70 million tons of gold. Yet, it would be much too expensive to recover that gold because of its very low concentration in the water. Minerals must be concentrated into deposits to make their collection economically feasible. A mineral deposit containing one or more minerals that can be extracted profitably is called an ore. Many minerals are commonly found together (e.g. quartz and gold; molybdenum, tin and tungsten; copper, lead and zinc; platinum and palladium).

If the material can be mined at a profit, the body constitutes an ore deposit. Typically, the term ore is used for only metal-bearing minerals, though the concept of ore as a non-renewable resource can be applied to valuable concentrations of fossil fuels, building stones, and other non-metal deposits, even groundwater. Mineral ores are found in just a relatively few areas, because it takes a special set of circumstances to create them. Therefore, the signs of a mineral deposit are often small and difficult to recognize. Locating deposits requires experience and knowledge. Geologists can search for years before finding an economic mineral deposit. Deposit size, its mineral content, extracting efficiency, processing costs and market value of the processed minerals are all factors that determine if a mineral deposit can be profitably developed. For example, when the market price of copper increased significantly in the 1970s, some marginal or low-grade copper deposits suddenly became profitable ore bodies.

References

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32. London, D. & Kontak, D. J. Granitic Pegmatites: Scientific Wonders and Economic Bonanzas. Elements 8, 257–261 (2012).

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39. Bromfield, C. S., Erickson, A. J., Haddadin, M. A. & Mehnert, H. H. Potassium-argon ages of intrusion, extrusion, and associated ore deposits, Park City mining district, Utah. Econ. Geol. 72, 837–848 (1977).

Contributors and Attributions

Kevin Raskoff- Monterey Peninsula College

Modified by Kyle Whittinghill from the following sources

• Metal Deposits and Industrial Minerals from Physical Geology by Steven Earle (licensed under a Creative Commons Attribution 4.0 International License)
• Minerals from AP Environmental Science by University of California College Prep
• Non-Renewable Resources from Environmental Science: A Canadian Perspective by Bill Freedman (Creative Commons Attribution NonCommercial)
• Mineral Resources and Mining from An Introduction to Geology by Chris Johnson, Matthew D. Affolter, Paul Inkenbrandt, & Cam Mosher (Geology Faculty at Salt Lake Community College), download free from OpenGeology
• Mineral Resources: Formation, Mining, Environmental Impact from Sustainability: A Comprehensive Foundation by Tom Theis and Jonathan Tomkin