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USGS National Map of Surficial Mineralogy

Landsat 7-based material mapping of the U.S. with inset showing one Landsat sceneMaps of exposed surface mineral groups derived from automated spectral analysis of Landsat 7 ETM+ and Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data are being generated for areas of the U.S. and its territories having potential for 1) undiscovered mineral deposits and (or) 2) environmental effects associated with mining and (or) unmined, hydrothermally-altered rocks. The mapping is being continually updated over the conterminous United States, and currently covers the western states with results 1,630 ASTER scenes and all of the lower 48 states with results from 447 Landsat 7 scenes.

More detailed and accurate mineral and vegetation maps generated from spectroscopic analysis of ASTER and "hyperspectral" data acquired by airborne imaging systems such as the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS), HyMap, and SpecTIR are also provided for comparison with the automated analysis products. Most of these detailed maps are available over important active or abandoned mining districts.

The maps are available online for interactive viewing in a web browser. The underlying map services can be accessed using ArcMap for integration with other geospatial data. References for the maps available in the online services are listed below.

An algorithm for the automated analysis of Landsat 8 Operational Land Imager (OLI) data has been developed, and preliminary results covering the western, conterminous United States are available for viewing and analysis as an internal USGS web service. The results will be posted to the public web application after supporting documentation has been published. The new "coastal aerosol" band present in OLI data provides important new capabilities for mineral mapping which will have particular impact on geoenvironmental site assessment and monitoring.

Support for this ongoing effort has been provided by the Updated National Mineral Resource Assessment and other projects of the USGS Mineral Resources Program.

Online Map Resources

Usage Guide for Large-Area Material Maps

The large-area material maps presented here were designed to aid in the identification of mineral groups in exposed rocks, soils, mine waste rock, and mill tailings on the Earth’s surface. Many man-made materials have spectral absorption features in the shortwave infrared region of the electromagnetic spectrum that can appear similar to those of various mineral groups at the spectral and spatial resolutions of Landsat and ASTER satellite data. For example, many plastics, asphalt, and other organic materials show deep absorption between 2.30 and 2.40 micrometers caused by a C-H combination band (Clark, 1999). This absorption can mimic those of the clay-sulfate-mica-marble mineral group detectable using Landsat Thematic Mapper (Rockwell, 2013a) and Operational Land Imager data, and the carbonate-propylitic mineral group detectable using the employed ASTER data analysis methodology (Rockwell, 2012). Some construction materials, including fine aggregates used in some asphalt shingles, have absorptions near 2.2 micrometers (Clark and others, 2007) that will be identified as the sericite-smectite mineral group in the ASTER-derived results. Therefore, mineral groups are often erroneously detected in built-up areas such as cities, towns, and along roadways. Reflections between man-made objects can also result in spurious spectral responses in such areas.

Scenes of Landsat and ASTER satellite data were selected based on several criteria, the most important of which are that the presence of clouds, smoke, haze, and snow is minimized, and that the scenes be acquired as close as possible to the northern hemisphere summer solstice in mid-June to insure maximal solar irradiance (solar elevation angle) and minimal terrain shadow. The number of scene acquisition dates was minimized by selecting as many high-quality scenes from a single satellite overpass (path, or swath) as possible (optimal scenes from a single swath acquired on the same day). Given these criteria, there may be substantial differences in scene acquisition date between scenes in a given swath and between those of adjacent swaths. The varying scene acquisition dates may result in seams of identified surface materials between scenes of the same and adjacent swaths, as the automated analysis methodologies utilize statistics generated from the data being processed, which are most often individual scenes. Most Landsat and ASTER scenes are analyzed individually and the resultant maps are then mosaicked into a single map. In rare cases, several scenes are mosaicked together prior to analysis. Variations in soil moisture and vegetation growth stage between scenes are another possible cause of seams in analysis results.

ASTER visible to near-infrared (VNIR) and short-wave infrared (SWIR) data are each collected by a unique telescope and detector array. In rare cases, the data in an ASTER scene collected by these two sensor systems are geometrically mis-registered to each other, resulting in corrupted pixel spectra. The VNIR data of one pixel will be combined with the SWIR data of another pixel located 30-100 meters away. For such scenes, the automated analysis methodology will result in an overabundance of pixels identified as “advanced argillic +/- ferric iron” (assigned a color of red in the maps) in areas where clay, sulfate, and mica minerals are abundant. Examples of scenes with such erroneous results are in the Independence Range in northern Nevada, and the area surrounding the Tintic mining district in the East Tintic Mountains near Eureka, Utah.

Suggested Citation

Additional Information

A poster describing the National Map of Surficial Mineralogy was presented at the Digital Mapping Techniques (DMT) 2013 conference.

DMT poster thumbnail
  • Reduced-resolution poster (9.4 MB): Download

  • Full-resolution poster (269 MB, 300 dpi): Download


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