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Todd Hoefen

Todd Hoefen is a Geophysicist with the Geology, Geophysics, and Geochemistry Science Center.

Science and Products

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Collage of airborne spectroscopy imagery

Spectroscopy and Hyperspectral Imaging of Critical Mineral Resources

Our project will characterize the primary critical minerals (minerals that contain critical elements in their base structure) that are not yet in the USGS Spectral Library. We propose to increase understanding of the spectral indicators of critical minerals using lab-based studies of hand specimens and drill core, hyperspectral field scanning, and hyperspectral images collected from aircraft.
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Mineral Resources Program, Geology, Geophysics, and Geochemistry Science Center, Spectroscopy Lab
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Spectroscopy and Hyperspectral Imaging of Critical Mineral Resources

Our project will characterize the primary critical minerals (minerals that contain critical elements in their base structure) that are not yet in the USGS Spectral Library. We propose to increase understanding of the spectral indicators of critical minerals using lab-based studies of hand specimens and drill core, hyperspectral field scanning, and hyperspectral images collected from aircraft.
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Hyperspectral camera measures output from calibration lamp

Development and Validation of Hyperspectral Imager for Field and Lab Scanning

The Mineral Resources Program has advanced methods of imaging spectroscopy (hyperspectral remote sensing) that are now used routinely by the earth science and remote sensing communities for mineral mapping, soil quality mapping, hazard mitigation, and other terrestrial and planetary applications. The USGS is highly qualified to advance this technology based on its world class expertise in mineral...
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Mineral Resources Program, Geology, Geophysics, and Geochemistry Science Center, Spectroscopy Lab
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Development and Validation of Hyperspectral Imager for Field and Lab Scanning

The Mineral Resources Program has advanced methods of imaging spectroscopy (hyperspectral remote sensing) that are now used routinely by the earth science and remote sensing communities for mineral mapping, soil quality mapping, hazard mitigation, and other terrestrial and planetary applications. The USGS is highly qualified to advance this technology based on its world class expertise in mineral...
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spectral library example

USGS High Resolution Spectral Library

The USGS Spectral Library contains reflectance spectra, including samples of minerals, rocks, soils, physically constructed as well as mathematically computed mixtures, plants, vegetation communities, microorganisms, and man-made materials. The samples and spectra collected were assembled for the purpose of using spectral features for the remote detection of these and similar materials. The latest...
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Mineral Resources Program, Geology, Geophysics, and Geochemistry Science Center, Spectroscopy Lab
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USGS High Resolution Spectral Library

The USGS Spectral Library contains reflectance spectra, including samples of minerals, rocks, soils, physically constructed as well as mathematically computed mixtures, plants, vegetation communities, microorganisms, and man-made materials. The samples and spectra collected were assembled for the purpose of using spectral features for the remote detection of these and similar materials. The latest...
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Hyperspectral images after the World Trade Center Twin Towers collapse

Environmental Studies of the World Trade Center Area After the September 11, 2001 Attack

USGS scientists conducted a remote sensing and mineralogical characterization study of lower Manhattan around the WTC after the September 11, 2001 attack.
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Geology, Geophysics, and Geochemistry Science Center, Denver Microbeam Laboratory, Spectroscopy Lab
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Environmental Studies of the World Trade Center Area After the September 11, 2001 Attack

USGS scientists conducted a remote sensing and mineralogical characterization study of lower Manhattan around the WTC after the September 11, 2001 attack.
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Geochemical data for carbonatite samples from the Mountain Pass rare earth element deposit, southeast California

This data release contains whole-rock major, minor, and trace element geochemical data for carbonatite samples from the Mountain Pass rare earth element (REE) deposit located in southeastern California. The Mountain Pass deposit is the largest REE deposit in the United States and in 2021, produced 43,000 metric tons (expressed as rare-earth-oxide equivalent; U.S. Geological Survey, 2022). Samples
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Mineral Resources Program, Geology, Geophysics, and Geochemistry Science Center

HySpex© VNIR-1800 and SWIR-384 imaging spectrometer radiance and reflectance data, with associated ASD© FieldSpecⓇ NG calibration data, collected at Cripple Creek Victor mine, Cripple Creek, Colorado, 2017

HySpex© VNIR-1800 and SWIR-384 imaging spectrometer radiance data were acquired on September 14, 2017 at the Cresson Pit of the Cripple Creek & Victor mine in Cripple Creek, Colorado. ASD© FieldSpecⓇ NG data were collected on September 13 and 14, 2017 at two calibration sites within the Cresson Pit imaged with the HySpex© imaging spectrometers. The HySpex© VNIR-1800 imaging spectrometer is a push
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Mineral Resources Program, Geology, Geophysics, and Geochemistry Science Center

Spectroscopy of Expanded Vermiculite Products and Insulation

This dataset contains descriptions and analytical data (i.e., electron microprobe, X-ray diffraction, spectral reflectance, and scanning electron microprobe analyses) for unexpanded and expanded vermiculite samples. These data are provided for 52 samples of vermiculite attic insulation, horticultural products, aggregate, and packing materials derived from mines near Enoree, South Carolina; Libby,
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Mineral Resources Program, Geology, Geophysics, and Geochemistry Science Center, Denver Microbeam Laboratory, Spectroscopy Lab

Corescan Hyperspectral Core Imager, Mark III system data collected for the characterization of mineral resources near Nabesna, Alaska, 2014-2016

Corescan Hyperspectral Core Imager Mark III (HCI-III) system data were acquired for hand samples, and subsequent billets made from the hand samples, collected during the U.S. Geological Survey (USGS) 2014, 2015, and 2016 field seasons in the Nabesna area of the eastern Alaska Range. This area contains exposed porphyry deposits and hand samples were collected throughout the region in support of the
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Geology, Geophysics, and Geochemistry Science Center

Imaging spectrometer reflectance data, mineral predominance map, and white mica wavelength position map, Nabesna Quadrangle, Alaska

Approximately 1,900 square kilometers of imagery were collected from July 14 to July 21, 2014 using a HyMap sensor (Cocks and others, 1998) mounted on a modified Piper Navajo aircraft. The survey area covered parts of the Wrangell and Nutzotin Mountains in the eastern Alaska Range near Nabesna, Alaska. The aircraft was flown at an altitude of approximately 5,050 meters (m) (3,480 m above the mean
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Mineral Resources Program, Geology, Geophysics, and Geochemistry Science Center

Whole rock, soil, sediment, x-ray diffraction, and electron microprobe analyses of samples from the Orange Hill-Bond Creek area, Nabesna Quadrangle, Alaska

This data release includes geochemical, x-ray diffraction mineralogical, and electron probe microanalysis (EPMA) data on rocks, soils, and sediments collected near the Orange Hill and Bond Creek porphyry copper deposits, Nabesna quadrangle, Alaska. Geochemical analyses were completed by a laboratory under contract with the U.S. Geological Survey (USGS). Electron microprobe and x-ray diffraction mi
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Mineral Resources Program, Geology, Geophysics, and Geochemistry Science Center, Denver Microbeam Laboratory, Spectroscopy Lab

Airborne imaging spectrometer data collected for characterizing mineral resources near Nabesna, Alaska, 2014

Imaging spectrometer (hyperspectral) data were collected using the HyMap sensor over the Nabesna Area of Interest (AOI) in the eastern Alaska Range, July 14 and July 21, 2014. The primary study area was a remote part of the eastern Alaska Range where porphyry deposits are exposed. The HyMap imaging spectrometer measured reflected sunlight in 126 narrow channels spanning the 0.4 to 2.5 micron wavel
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Mineral Resources Program, Geology, Geophysics, and Geochemistry Science Center

USGS Spectral Library Version 7 Data

This data release provides the U.S. Geological Survey (USGS) Spectral Library Version 7 and all related documents. The library contains spectra measured with laboratory, field, and airborne spectrometers. The instruments used cover wavelengths from the ultraviolet to the far infrared (0.2 to 200 microns). Laboratory samples of specific minerals, plants, chemical compounds, and man-made materials w
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Mineral Resources Program, Geology, Geophysics, and Geochemistry Science Center
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Multiscale hyperspectral imaging of hydrothermal alteration in Yellowstone National Park, USA

Imaging spectroscopy (hyperspectral imaging) data have mainly been used to map surface materials covering relatively small areas from airborne sensors over the past 20+ years. As part of the U.S. Geological Survey Integrated hyperspectral, geophysical and geochemical studies of Yellowstone National Park hydrothermal systems project, we have collected multiscale imaging spectrometer data including
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Mineral Resources Program, Geology, Geophysics, and Geochemistry Science Center, Spectroscopy Lab

Mineral Mapping of the Battle Mountain District, Nevada, USA, Using AVIRIS-Classic and SpecTIR Inc. AisaFENIX 1K Imaging Spectrometer Datasets

Imaging spectroscopy (hyperspectral imaging) has been used to successfully map minerals at the outcrop, deposit, district, and regional scale. This contribution presents spectral-based mineral maps of the Battle Mountain mining district, Nevada, USA, generated using multi-scale airborne imaging and ground-based point spectrometers. Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) and AisaFE
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Geology, Geophysics, and Geochemistry Science Center

Imaging spectroscopy for the detection, assessment and monitoring of natural and anthropogenic hazards

Natural and anthropogenic hazards have the potential to impact all aspects of society including its economy and the environment. Diagnostic data to inform decision-making are critical for hazard management whether for emergency response, routine monitoring or assessments of potential risks. Imaging spectroscopy (IS) has unique contributions to make via the ability to provide some key quantitative
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Geology, Geophysics, and Geochemistry Science Center, Spectroscopy Lab

Multiscale hyperspectral imaging of the Orange Hill Porphyry Copper Deposit, Alaska, USA, with laboratory-, field-, and aircraft-based imaging spectrometers

In the past decade, use of hyperspectral imaging (imaging spectroscopy) for mineral exploration and mining operations has been increasing at different spatial scales. In this paper, we focus on recent trends in applying imaging spectrometer data to: 1) airborne imaging of high latitude deposits, 2) field-based imaging of outcrops, and 3) laboratory-level imaging of geologic samples. Comparing mine
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Geology, Geophysics, and Geochemistry Science Center, Spectroscopy Lab

Characterizing the source of potentially asbestos-bearing commercial vermiculite insulation using in situ IR spectroscopy

Commercially produced vermiculite insulation from Libby, Montana, contains trace levels of asbestiform amphibole, which is known to cause asbestos-related diseases. When vermiculite insulation is found in a building, evaluation for its potential asbestos content traditionally involves collecting a sample from an attic or wall and submitting it for time-consuming analyses at an off-site laboratory.
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Geology, Geophysics, and Geochemistry Science Center, Denver Microbeam Laboratory, Spectroscopy Lab

Application of imaging spectroscopy for mineral exploration in Alaska: A study over porphyry Cu deposits in the eastern Alaska Range

The U.S. Geological Survey tested the utility of imaging spectroscopy (also referred to as hyperspectral remote sensing) as an aid to regional mineral exploration efforts in remote parts of Alaska. Airborne imaging spectrometer data were collected in 2014 over unmined porphyry Cu deposits in the eastern Alaska Range using the HyMap™ sensor. Maps of the distributions of predominant minerals, made b
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Geology, Geophysics, and Geochemistry Science Center, Geology, Energy & Minerals Science Center

USGS Spectral Library Version 7

We have assembled a library of spectra measured with laboratory, field, and airborne spectrometers. The instruments used cover wavelengths from the ultraviolet to the far infrared (0.2 to 200 microns [μm]). Laboratory samples of specific minerals, plants, chemical compounds, and manmade materials were measured. In many cases, samples were purified, so that unique spectral features of a material ca
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Mineral Resources Program, Geology, Geophysics, and Geochemistry Science Center, Denver Microbeam Laboratory, Spectroscopy Lab

Environmental implications of the use of sulfidic back-bay sediments for dune reconstruction — Lessons learned post Hurricane Sandy

Some barrier-island dunes damaged or destroyed by Hurricane Sandy's storm surges in October 2012 have been reconstructed using sediments dredged from back bays. These sand-, clay-, and iron sulfide-rich sediments were used to make berm-like cores for the reconstructed dunes, which were then covered by beach sand. In November 2013, we sampled and analyzed partially weathered materials collected fro
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Ecosystems Mission Area, Toxic Substances Hydrology, Environmental Health Program, Geology, Geophysics, and Geochemistry Science Center, Spectroscopy Lab

Hyperspectral surveying for mineral resources in Alaska

Alaska is a major producer of base and precious metals and has a high potential for additional undiscovered mineral resources. However, discovery is hindered by Alaska’s vast size, remoteness, and rugged terrain. New methods are needed to overcome these obstacles in order to fully evaluate Alaska’s geology and mineral resource potential. Hyperspectral surveying is one method that can be used to ra
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Energy and Minerals Mission Area, Mineral Resources Program, Geology, Energy & Minerals Science Center, Geology, Geophysics, and Geochemistry Science Center, Spectroscopy Lab

Trace elements in stormflow, ash, and burned soil following the 2009 station fire in southern California

Most research on the effects of wildfires on stream water quality has focused on suspended sediment and nutrients in streams and water bodies, and relatively little research has examined the effects of wildfires on trace elements. The purpose of this study was two-fold: 1) to determine the effect of the 2009 Station Fire in the Angeles National Forest northeast of Los Angeles, CA on trace element
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Water Resources Mission Area, Mineral Resources Program, California Water Science Center, Geology, Geophysics, and Geochemistry Science Center, Spectroscopy Lab

Mapping surficial minerals at high latitudes: The USGS 2014 imaging spectrometer data collection in Alaska

Passive optical remote sensing of high latitude regions faces many challenges including a short acquisition season and poor illumination due to low solar elevation. Additional complications are encountered in the identification of surface minerals for mineral resource characterization because minerals of interest commonly are exposed on steep terrain, further challenging reflectance retrieval and
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Mineral Resources Program, Geology, Energy & Minerals Science Center, Geology, Geophysics, and Geochemistry Science Center, Spectroscopy Lab

The environmental and medical geochemistry of potentially hazardous materials produced by disasters

Many natural or human-caused disasters release potentially hazardous materials (HM) that may pose threats to the environment and health of exposed humans, wildlife, and livestock. This chapter summarizes the environmentally and toxicologically significant physical, mineralogical, and geochemical characteristics of materials produced by a wide variety of recent disasters, such as volcanic eruptions
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Geology, Geophysics, and Geochemistry Science Center, Geology, Minerals, Energy, and Geophysics Science Center, Spectroscopy Lab

USGS Digital Spectral Library

References for material identification in remote sensing images. The library contains spectral reflectance data for of hundreds of materials, including minerals, vegetation, organic and volatile compounds, and man-made materials.

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Mineral Resources Program, Geology, Geophysics, and Geochemistry Science Center, Spectroscopy Lab
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Igniting a New Trend in Public Safety

U.S. Geological Survey scientists and partners are taking technology to the next level, using unmanned aircraft systems (UAS), commonly called drones...

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USGS Spectral Library gets Ultra- and Hyper- Revamp

We've got a library full of spectral signatures, like a police fingerprint library for minerals and other substances!

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