Map showing locations of placer mines in the Alaska Resource Data File (ARDF, red crosses), primary mineral districts that contain targeted critical minerals (black boxes) and locations that were sampled by the USGS in 2022 and 2023 (yellow stars).
Susan Karl
Sedimentology, stratigraphy, tectonics, geochemistry, and economic geology of southeast Alaska
Science and Products
Alaska Mine Waste
Critical minerals are essential to the U.S. economy and national security, have a supply chain that is vulnerable to disruption, and serve an essential function in the manufacturing of many products. Often, critical minerals are found as co- or by-products in deposits mined for precious or base metals. The projects described here develop an interdisciplinary (geological, societal, ecological) and...
Critical Minerals in Alaska Placer Deposits and Southeast Alaska Mineral Systems
Critical minerals have been identified in most Alaskan placers, yet little is known about the concentration of these phases. Historic and active placer mines have typically produced gold and are widespread across Alaska. Activity in the placer districts has resulted in gravel piles and sluice tailings that are products of gold mining. Gold has been the traditional target of placer mining; however...
Alaska Critical Mineral Resource Assessments
Alaska has potential for a wide range of critical minerals including, but not limited to, graphite, lithium, tin, tungsten, rare earth elements, and platinum-group elements.
GIS Prospectivity Analysis for Critical Minerals in Ore-Forming Systems in Alaska
Alaska is dominated by a history of tectonic events that foster mobilization and concentration of a wide variety of mineral commodities that are critical to the US economy and are vital to national defense, renewable-energy, and emerging electronics technologies.
Petrology, Tectonic Setting, and Potential for Concentration of Rare Earth Elements (REE) and High Field Strength Elements (HFSE) in the High-K Darby and Kachauik Plutons, Seward Peninsula, Alaska
One of the geologic environments that host rare earth and other critical and strategic element deposits are alkaline intrusive rocks.
Alaska locations of placer tailings sampling sites
Map showing locations of placer mines in the Alaska Resource Data File (ARDF, red crosses), primary mineral districts that contain targeted critical minerals (black boxes) and locations that were sampled by the USGS in 2022 and 2023 (yellow stars).
Uhler Creek
Scientist sieving a sample of gold placer tailings to analyze for critical mineral contents in Uhler Creek, a tributary to the South Fork of the Forty Mile River in east central Alaska.
Scientist sieving a sample of gold placer tailings to analyze for critical mineral contents in Uhler Creek, a tributary to the South Fork of the Forty Mile River in east central Alaska.
Cassiterite Creek
Scientist sieving a sample of tin placer tailings in Cassiterite Creek on the western Seward Peninsula.
Scientist sieving a sample of tin placer tailings in Cassiterite Creek on the western Seward Peninsula.
Dredge
Historic dredge and large volume of gold placer tailings that contain platinum group and chromium critical minerals on the Salmon River near Goodnews Bay, Alaska. Dragline-sluice tailings are in the foreground, stacked dredge tailings are in the background near the dredge.
Historic dredge and large volume of gold placer tailings that contain platinum group and chromium critical minerals on the Salmon River near Goodnews Bay, Alaska. Dragline-sluice tailings are in the foreground, stacked dredge tailings are in the background near the dredge.
Clear Creek
Scientists collecting a 1/5 yard composite sample in blue 5-gallon buckets from gold placer tailings to analyze for critical mineral contents in Clear Creek, in the Zane Hills north central Alaska.
Scientists collecting a 1/5 yard composite sample in blue 5-gallon buckets from gold placer tailings to analyze for critical mineral contents in Clear Creek, in the Zane Hills north central Alaska.
Chicken Creek
Scientist checking a gold pan for gold and critical minerals in placer tailings on lower Chicken Creek near Flat, Alaska, in the Kuskokwim Mountains. A sample was collected from legacy gold placer tailings at this site and 7 others in the Flat mining district to determine the critical mineral contents of tailings from which only gold has been removed.
Scientist checking a gold pan for gold and critical minerals in placer tailings on lower Chicken Creek near Flat, Alaska, in the Kuskokwim Mountains. A sample was collected from legacy gold placer tailings at this site and 7 others in the Flat mining district to determine the critical mineral contents of tailings from which only gold has been removed.
USGS geologist recording data on graphite mineralization in core sample
USGS geologist George Case is recording data on graphite mineralization in core sample from the Graphite Creek deposit in Nome, Alaska. The purpose of this research is to determine the genesis and key attributes of the world class large flake Graphite Creek deposit on the western Seward Peninsula, Alaska.
USGS geologist George Case is recording data on graphite mineralization in core sample from the Graphite Creek deposit in Nome, Alaska. The purpose of this research is to determine the genesis and key attributes of the world class large flake Graphite Creek deposit on the western Seward Peninsula, Alaska.
Evidence of previous exploration
A geologist, George Case, stands in front of an adit, an entrance to an underground mine, in the Graphite Creek Deposit on the Seward Peninsula, Alaska.
A geologist, George Case, stands in front of an adit, an entrance to an underground mine, in the Graphite Creek Deposit on the Seward Peninsula, Alaska.
View of fog and clouds in the Aaron Creek valley, Alaska
View of fog and clouds in the Aaron Creek valley with tail of R66 helicopter in right foreground.
View of fog and clouds in the Aaron Creek valley with tail of R66 helicopter in right foreground.
USGS Geologist approaches an old exploration trench
Geologist George Case approaches an old exploration trench exposing stratiform Ag-Sn-Pb-Zn mineralization in the Groundhog Basin deposit area.
Geologist George Case approaches an old exploration trench exposing stratiform Ag-Sn-Pb-Zn mineralization in the Groundhog Basin deposit area.
Rock hammer shows meter-scale width of a felsic sill
Rock hammer shows meter-scale width of a felsic sill associated with zinnwaldite-bearing Sn-granite at the Groundhog Basin Ag-Sn-Pb-Zn deposit. The layered host rocks to the sill are garnet-quartz-biotite gneiss.
Rock hammer shows meter-scale width of a felsic sill associated with zinnwaldite-bearing Sn-granite at the Groundhog Basin Ag-Sn-Pb-Zn deposit. The layered host rocks to the sill are garnet-quartz-biotite gneiss.
USGS geologist approaches helicopter with samples
USGS geologist George Case approaches an R66 helicopter with samples collected from mineralized rocks near the Groundhog Basin Ag-Sn-Pb-Zn deposit.
USGS geologist George Case approaches an R66 helicopter with samples collected from mineralized rocks near the Groundhog Basin Ag-Sn-Pb-Zn deposit.
USGS geologist breaks mineralized rocks for examination and sample collection
USGS geologist George Case breaks mineralized rocks for examination and sample collection at the Groundhog Basin Ag-Sn-Pb-Zn deposit.
USGS geologist George Case breaks mineralized rocks for examination and sample collection at the Groundhog Basin Ag-Sn-Pb-Zn deposit.
Geologist examines rocks at Darby Pluton, AK
USGS Geologist George Case examines granitic rocks in preparation for collecting samples for geochemistry and geochronology near the Boulder Creek prospect at the north end of the Darby pluton on the eastern Seward Peninsula.
USGS Geologist George Case examines granitic rocks in preparation for collecting samples for geochemistry and geochronology near the Boulder Creek prospect at the north end of the Darby pluton on the eastern Seward Peninsula.
Potassium feldspar phenocrysts in syenite
Stretched phenocrysts of potassium feldspar in syenite of the Kachauik pluton on the Bering Sea coast of the southeastern Seward Peninsula.
Stretched phenocrysts of potassium feldspar in syenite of the Kachauik pluton on the Bering Sea coast of the southeastern Seward Peninsula.
Torrs of the Ruby Batholith
Scintillometer and torrs of the Melozitna granite in the Ruby batholith. This granite contains abundant monazite and high levels of thorium and rare earth elements. This area is part of the Bureau of Land Management's Central Yukon Planning Area, which USGS did a mineral assessment of in 2015.
Scintillometer and torrs of the Melozitna granite in the Ruby batholith. This granite contains abundant monazite and high levels of thorium and rare earth elements. This area is part of the Bureau of Land Management's Central Yukon Planning Area, which USGS did a mineral assessment of in 2015.
Shearing of the Melozitna Granite
Geologist and cataclastic shear zones in the Melozitna granite in the Ruby batholith. This granite contains abundant monazite and high levels of thorium and rare earth elements.
Geologist and cataclastic shear zones in the Melozitna granite in the Ruby batholith. This granite contains abundant monazite and high levels of thorium and rare earth elements.
Taking soil samples
USGS researchers collecting a soil sample for rare earth elements at the Roy Creek prospect, Alaska. Jamey Jones is holding the bag while Erin Todd shovels soil into the bag.
USGS researchers collecting a soil sample for rare earth elements at the Roy Creek prospect, Alaska. Jamey Jones is holding the bag while Erin Todd shovels soil into the bag.
Panning for Rare Earths
A field assistant pans for monazite and rare earth minerals in Wolf Creek, which cuts through the Melozitna granite. This area is part of the Bureau of Land Management's Central Yukon Planning Area, where USGS did a critical mineral assessment in 2015.
A field assistant pans for monazite and rare earth minerals in Wolf Creek, which cuts through the Melozitna granite. This area is part of the Bureau of Land Management's Central Yukon Planning Area, where USGS did a critical mineral assessment in 2015.
Science and Products
Alaska Mine Waste
Critical minerals are essential to the U.S. economy and national security, have a supply chain that is vulnerable to disruption, and serve an essential function in the manufacturing of many products. Often, critical minerals are found as co- or by-products in deposits mined for precious or base metals. The projects described here develop an interdisciplinary (geological, societal, ecological) and...
Critical Minerals in Alaska Placer Deposits and Southeast Alaska Mineral Systems
Critical minerals have been identified in most Alaskan placers, yet little is known about the concentration of these phases. Historic and active placer mines have typically produced gold and are widespread across Alaska. Activity in the placer districts has resulted in gravel piles and sluice tailings that are products of gold mining. Gold has been the traditional target of placer mining; however...
Alaska Critical Mineral Resource Assessments
Alaska has potential for a wide range of critical minerals including, but not limited to, graphite, lithium, tin, tungsten, rare earth elements, and platinum-group elements.
GIS Prospectivity Analysis for Critical Minerals in Ore-Forming Systems in Alaska
Alaska is dominated by a history of tectonic events that foster mobilization and concentration of a wide variety of mineral commodities that are critical to the US economy and are vital to national defense, renewable-energy, and emerging electronics technologies.
Petrology, Tectonic Setting, and Potential for Concentration of Rare Earth Elements (REE) and High Field Strength Elements (HFSE) in the High-K Darby and Kachauik Plutons, Seward Peninsula, Alaska
One of the geologic environments that host rare earth and other critical and strategic element deposits are alkaline intrusive rocks.
Alaska locations of placer tailings sampling sites
Map showing locations of placer mines in the Alaska Resource Data File (ARDF, red crosses), primary mineral districts that contain targeted critical minerals (black boxes) and locations that were sampled by the USGS in 2022 and 2023 (yellow stars).
Map showing locations of placer mines in the Alaska Resource Data File (ARDF, red crosses), primary mineral districts that contain targeted critical minerals (black boxes) and locations that were sampled by the USGS in 2022 and 2023 (yellow stars).
Uhler Creek
Scientist sieving a sample of gold placer tailings to analyze for critical mineral contents in Uhler Creek, a tributary to the South Fork of the Forty Mile River in east central Alaska.
Scientist sieving a sample of gold placer tailings to analyze for critical mineral contents in Uhler Creek, a tributary to the South Fork of the Forty Mile River in east central Alaska.
Cassiterite Creek
Scientist sieving a sample of tin placer tailings in Cassiterite Creek on the western Seward Peninsula.
Scientist sieving a sample of tin placer tailings in Cassiterite Creek on the western Seward Peninsula.
Dredge
Historic dredge and large volume of gold placer tailings that contain platinum group and chromium critical minerals on the Salmon River near Goodnews Bay, Alaska. Dragline-sluice tailings are in the foreground, stacked dredge tailings are in the background near the dredge.
Historic dredge and large volume of gold placer tailings that contain platinum group and chromium critical minerals on the Salmon River near Goodnews Bay, Alaska. Dragline-sluice tailings are in the foreground, stacked dredge tailings are in the background near the dredge.
Clear Creek
Scientists collecting a 1/5 yard composite sample in blue 5-gallon buckets from gold placer tailings to analyze for critical mineral contents in Clear Creek, in the Zane Hills north central Alaska.
Scientists collecting a 1/5 yard composite sample in blue 5-gallon buckets from gold placer tailings to analyze for critical mineral contents in Clear Creek, in the Zane Hills north central Alaska.
Chicken Creek
Scientist checking a gold pan for gold and critical minerals in placer tailings on lower Chicken Creek near Flat, Alaska, in the Kuskokwim Mountains. A sample was collected from legacy gold placer tailings at this site and 7 others in the Flat mining district to determine the critical mineral contents of tailings from which only gold has been removed.
Scientist checking a gold pan for gold and critical minerals in placer tailings on lower Chicken Creek near Flat, Alaska, in the Kuskokwim Mountains. A sample was collected from legacy gold placer tailings at this site and 7 others in the Flat mining district to determine the critical mineral contents of tailings from which only gold has been removed.
USGS geologist recording data on graphite mineralization in core sample
USGS geologist George Case is recording data on graphite mineralization in core sample from the Graphite Creek deposit in Nome, Alaska. The purpose of this research is to determine the genesis and key attributes of the world class large flake Graphite Creek deposit on the western Seward Peninsula, Alaska.
USGS geologist George Case is recording data on graphite mineralization in core sample from the Graphite Creek deposit in Nome, Alaska. The purpose of this research is to determine the genesis and key attributes of the world class large flake Graphite Creek deposit on the western Seward Peninsula, Alaska.
Evidence of previous exploration
A geologist, George Case, stands in front of an adit, an entrance to an underground mine, in the Graphite Creek Deposit on the Seward Peninsula, Alaska.
A geologist, George Case, stands in front of an adit, an entrance to an underground mine, in the Graphite Creek Deposit on the Seward Peninsula, Alaska.
View of fog and clouds in the Aaron Creek valley, Alaska
View of fog and clouds in the Aaron Creek valley with tail of R66 helicopter in right foreground.
View of fog and clouds in the Aaron Creek valley with tail of R66 helicopter in right foreground.
USGS Geologist approaches an old exploration trench
Geologist George Case approaches an old exploration trench exposing stratiform Ag-Sn-Pb-Zn mineralization in the Groundhog Basin deposit area.
Geologist George Case approaches an old exploration trench exposing stratiform Ag-Sn-Pb-Zn mineralization in the Groundhog Basin deposit area.
Rock hammer shows meter-scale width of a felsic sill
Rock hammer shows meter-scale width of a felsic sill associated with zinnwaldite-bearing Sn-granite at the Groundhog Basin Ag-Sn-Pb-Zn deposit. The layered host rocks to the sill are garnet-quartz-biotite gneiss.
Rock hammer shows meter-scale width of a felsic sill associated with zinnwaldite-bearing Sn-granite at the Groundhog Basin Ag-Sn-Pb-Zn deposit. The layered host rocks to the sill are garnet-quartz-biotite gneiss.
USGS geologist approaches helicopter with samples
USGS geologist George Case approaches an R66 helicopter with samples collected from mineralized rocks near the Groundhog Basin Ag-Sn-Pb-Zn deposit.
USGS geologist George Case approaches an R66 helicopter with samples collected from mineralized rocks near the Groundhog Basin Ag-Sn-Pb-Zn deposit.
USGS geologist breaks mineralized rocks for examination and sample collection
USGS geologist George Case breaks mineralized rocks for examination and sample collection at the Groundhog Basin Ag-Sn-Pb-Zn deposit.
USGS geologist George Case breaks mineralized rocks for examination and sample collection at the Groundhog Basin Ag-Sn-Pb-Zn deposit.
Geologist examines rocks at Darby Pluton, AK
USGS Geologist George Case examines granitic rocks in preparation for collecting samples for geochemistry and geochronology near the Boulder Creek prospect at the north end of the Darby pluton on the eastern Seward Peninsula.
USGS Geologist George Case examines granitic rocks in preparation for collecting samples for geochemistry and geochronology near the Boulder Creek prospect at the north end of the Darby pluton on the eastern Seward Peninsula.
Potassium feldspar phenocrysts in syenite
Stretched phenocrysts of potassium feldspar in syenite of the Kachauik pluton on the Bering Sea coast of the southeastern Seward Peninsula.
Stretched phenocrysts of potassium feldspar in syenite of the Kachauik pluton on the Bering Sea coast of the southeastern Seward Peninsula.
Torrs of the Ruby Batholith
Scintillometer and torrs of the Melozitna granite in the Ruby batholith. This granite contains abundant monazite and high levels of thorium and rare earth elements. This area is part of the Bureau of Land Management's Central Yukon Planning Area, which USGS did a mineral assessment of in 2015.
Scintillometer and torrs of the Melozitna granite in the Ruby batholith. This granite contains abundant monazite and high levels of thorium and rare earth elements. This area is part of the Bureau of Land Management's Central Yukon Planning Area, which USGS did a mineral assessment of in 2015.
Shearing of the Melozitna Granite
Geologist and cataclastic shear zones in the Melozitna granite in the Ruby batholith. This granite contains abundant monazite and high levels of thorium and rare earth elements.
Geologist and cataclastic shear zones in the Melozitna granite in the Ruby batholith. This granite contains abundant monazite and high levels of thorium and rare earth elements.
Taking soil samples
USGS researchers collecting a soil sample for rare earth elements at the Roy Creek prospect, Alaska. Jamey Jones is holding the bag while Erin Todd shovels soil into the bag.
USGS researchers collecting a soil sample for rare earth elements at the Roy Creek prospect, Alaska. Jamey Jones is holding the bag while Erin Todd shovels soil into the bag.
Panning for Rare Earths
A field assistant pans for monazite and rare earth minerals in Wolf Creek, which cuts through the Melozitna granite. This area is part of the Bureau of Land Management's Central Yukon Planning Area, where USGS did a critical mineral assessment in 2015.
A field assistant pans for monazite and rare earth minerals in Wolf Creek, which cuts through the Melozitna granite. This area is part of the Bureau of Land Management's Central Yukon Planning Area, where USGS did a critical mineral assessment in 2015.
*Disclaimer: Listing outside positions with professional scientific organizations on this Staff Profile are for informational purposes only and do not constitute an endorsement of those professional scientific organizations or their activities by the USGS, Department of the Interior, or U.S. Government