Layered deposit of heavy-mineral sands in a modern beach at Folly Beach, South Carolina.
Photograph by Carleton Bern, USGS.
We are assessing the extent of industrial mineral resources hosted by heavy-mineral sands in the coastal plain of the southeastern United States. “Heavy-mineral sands” (HMS) is a term commonly used in industry and geologic literature to describe layered sediments deposited in coastal environments that contain dense (“heavy”) minerals of economic value. The heavy minerals extracted from these coastal deposits contain titanium, zirconium, and rare earth elements, needed to manufacture, for example, modern electronics for consumer and defense applications. The extensive heavy-mineral sand deposits in the southeastern U.S. coastal plain represent an enormous, under-utilized domestic source of these mineral resources. The United States is heavily reliant on imports of these mineral commodities, which are critical to the U.S. economy and security. The characteristics and global importance of heavy-minerals sand deposits are described in USGS Scientific Investigations Report 2010-5070L, ‘Deposit model for heavy-mineral sands in coastal environments’.
U.S. Geological Survey, 2016, Mineral commodity summaries 2016: U.S. Geological Survey, 202 p., http://dx.doi.org/10.3133/70140094.
Van Gosen, B.S., Fey, D.L., Shah, A.K., Verplanck, P.L., and Hoefen, T.M., 2014, Deposit model for heavy-mineral sands in coastal environments: U.S. Geological Survey Scientific Investigations Report 2010–5070–L, 51 p., http://dx.doi.org/10.3133/sir20105070L.
Van Gosen, B.S., Verplanck, P.L., Long, K.R., Gambogi, Joseph, and Seal, R.R., II, 2014, The rare-earth elements—Vital to modern technologies and lifestyles: U.S. Geological Survey Fact Sheet 2014–3078, 4 p., http://dx.doi.org/10.3133/fs20143078.
Woodruff, Laurel, and Bedinger, George, 2013, Titanium—Light, strong, and white: U.S. Geological Survey Fact Sheet 2013–3059, 2 p., http://pubs.usgs.gov/fs/2013/3059/.
The Concord heavy-mineral-sands mine of Iluka Resources in south-central Virginia
. The mine excavates sand-silt deposits that contain about 4 percent heavy minerals, which were deposited along a shoreline that existed here between 3.5 and 3.0 million years ago. These ores are processed at nearby separation plants to recover the heavy minerals. The principal products are the titanium-rich minerals ilmenite, leucoxene, and rutile, and the zirconium-rich mineral zircon. Photo by Bradley Van Gosen, USGS.
In this project we will:
- Investigate the regional extent of potentially mineable heavy-mineral sand resources in the entire coastal plain of the southeastern United States, and conduct research to unravel the geologic processes that formed these deposits.
- Research and determine the socio-economic factors that can affect the mining of heavy-mineral sand deposits, from discovery to production:
- Economic factors
- Social issues
- Environmental issues
USGS mineral economists will place these coastal plain deposits in context with those that are already established in the global supply chain (a market analysis–materials flow study of heavy-mineral sand resources).
Regional Extent of Mineable Heavy-Mineral Sand Resources
- Map the regional scale, spatial distribution of heavy-mineral sand deposits in the coastal plain of the southeastern U.S. The spatial distribution is important because it (along with many other factors) affects whether mining is feasible and it provides a regional-scale context for small-scale, site-specific studies.
- Map the probabilities for high concentrations of heavy-mineral sands in the southeastern U.S. The maps will identify favorable areas where industry could conduct exploration and development.
- Investigate the regional-scale geologic processes that formed the heavy-mineral sand deposits. Understanding these processes will help us interpret both the spatial distributions maps and the probability maps. Also, this understanding will help us ensure the accuracy of both sets of maps.
To be comprehensive, the determination of the extent of heavy-mineral sand deposits will use multiple, existing earth-science data sets, such as geochemical, geological, geophysical, hydrological, and geographical data. Initial analyses of these different data sets were conducted by Ellefsen and others (USGS Open-File Report 2015-1111), establishing the foundation for this investigation.
Socio-Economic Factors Affecting the Mining of Heavy-Mineral Sand Deposits
- Compare the character of the undeveloped southeastern U.S. heavy-mineral sand deposits to analogous explored deposits and active operations in other parts of the world. This comparison will place into context the economic potential of the U.S. deposits as a domestic supply source.
- Examine the estimated lead time requirements for development.
- Examine the potential influence on reduction of import reliance.
- Develop flow figures that display the concept of mine to market and include byproducts, coproducts, and waste products of this deposit type.
- Illustrate the mining and mineral processing requirements, waste generation, resource requirements, and infrastructure requirements. These requirements include land, grade, tonnage, water, energy, site operations, fuel, and other factors.
- Examine the associated environmental factors and social issues affected by competing values that may restrict development. The competing values involve
- land disturbance,
- urban development,
- recreational values,
- national forest,
- national seashores,
- water quality and quantity, and
- radiation issues associated with the sale, stockpiling, and reburial of thorium-bearing monazite and xenotime.
Ellefsen, K.J., Van Gosen, B.S., Fey, D.L., Budahn, J.R., Smith, S.M., and Shah, A.K., 2015, First steps of integrated spatial modeling of titanium, zirconium, and rare earth element resources within the Coastal Plain sediments of the Southeastern United States: U.S. Geological Survey Open-File Report 2015–1111, 40 p., http://dx.doi.org/10.3133/ofr20151111.