Jeffrey L Mauk
Jeff Mauk is a Research Geologist with the Geology, Geophysics, and Geochemistry Science Center.
Science and Products
USMIN Mineral Deposit Database
Our objective is to develop a national-scale, geospatial database that is the authoritative source of the most important mines, mineral deposits, and mineral districts of the United States.
Sediment-Hosted Copper Deposits in the Lake Superior Portion of the Midcontinent Rift System
This project is focused on the sediment-hosted copper deposits of the Midcontinent Rift, with three main objectives: 1) describe the ore mineralogy and geochemistry of the White Pine and Copperwood deposits, 2) evaluate whether hydrothermal alteration in footwall rocks can be used as a vector towards ore, and 3) provide a careful scoping study to evaluate whether unconventional platinum-group...
Filter Total Items: 20
GIS Data for Geologic Maps of Ravalli Group and other Mesoproterozoic Belt Supergroup Strata Based on Mapping by ASARCO in Northern Idaho and Northwestern Montana
The data release for geologic maps of Ravalli Group and other Mesoproterozoic Belt Supergroup strata in northern Idaho and northwestern Montana is a digital, Geologic Map Schema (GeMS)-compliant version of maps published in U.S. Geological Survey (USGS) Open-File Report 2001-438 (Boleneus and others, 2001). The new digital data present attribute tables and geospatial features (points, lines, and p
The major, minor, and trace element geochemistry of mineral scales from The Geysers geothermal field, California, USA
This data release provides quantitative whole rock geochemical results from The Geysers vapor-dominated geothermal field in California. The concentrations of major elements are reported in oxide weight percent by wavelength dispersive x-ray fluorescence (WDXRF), the concentrations for sixty elements are reported in elemental weight percent (pct) or parts per million (ppm) from inductively coupled
Semiquantitative mineralogy results from powder X-ray diffraction (XRD) analyses of mineral scales from The Geysers geothermal field, California, USA
This data release provides semiquantitative mineralogy results from X-ray diffraction (XRD) analyses of mineral scales from The Geysers vapor-dominated geothermal field in California. The mineral species and their abundances are reported in weight percent and values have been normalized to total 100 percent for each sample. The X-ray diffraction results show that the mineral samples from the wellh
Indium deposits in the United States
This U.S. Geological Survey (USGS) data release provides the descriptions of the only U.S. sites-including mining districts, mineral occurrences, and mine features-that have reported production and (or) resources of indium (In). This dataset contains the Bingham and West Desert deposits in Utah, and the Chino site in New Mexico.
Indium is considered a critical and strategic mineral because of its
Whole rock major, minor, and trace element geochemistry of the upper part of the Mount Emmons-Redwell porphyry molybdenum (Climax-type) deposit, Redwell Basin, Crested Butte, Colorado
This U.S. Geological Survey (USGS) data release provides whole rock major, minor, and trace element geochemical data from the fluorine-rich Mount Emmons-Redwell porphyry molybdenum (Climax-type) deposit (Mt. Emmons-Redwell deposit), located approximately 5.6 km (3.5 mi) northwest of Crested Butte, Colorado. The Mt. Emmons-Redwell deposit partly underlies Redwell Basin on the northwest flank of Mou
Graphite deposits in the United States
This U.S. Geological Survey (USGS) data release provides the descriptions of 10 U.S. sites that include mineral regions, mineral occurrences, and mine features that contain enrichments of graphite. To be included in this data release, sites must have a contained resource and (or) past production of more than 1,000 metric tons of graphite, which is approximately 3 percent of the average annual U.S.
Table of Electron Probe Microanalyses of Native Copper and Sulfide Minerals from the White Pine Sediment-hosted Copper Deposit, Michigan
This data release provides electron microprobe geochemical data that was collected as part of a scoping study to evaluate whether unconventional critical element resources may be associated with sediment-hosted copper systems in the Midcontinent Rift. We report abundances of trace elements in native copper and sulfide minerals in 12 thin sections from samples of the Mesoproterozoic lower Nonesuch
Hydrologic and geophysical data from high-elevation boreholes in Redwell Basin near Crested Butte, Colorado
Four boreholes (MW1, MW1UZ, MW2, MW2.1) were drilled in the fall of 2017 and summer of 2018 in upper Redwell Basin, a headwater catchment underlain by hydrothermally altered sedimentary rock in the Elk Mountains near the town of Crested Butte, Colorado. The boreholes were continuously cored using a wireline HQ-sized coring system and sample a combination of Quaternary-aged surficial colluvium and
Multi-element geochemical analyses of samples from the Mesoproterozoic Nonesuch Formation and Copper Harbor Conglomerate at the Copperwood copper deposit, Western Syncline, Michigan, USA
This data release provides multi-element data for drill core samples from the Mesoproterozoic Nonesuch Formation and Copper Harbor Conglomerate at the Copperwood copper deposit, Michigan, USA. Copper was determined by assay, and sulfur by inductively coupled plasma-optical emission spectrometry (ICP-OES) after aqua regia digestion for most samples. Multi-element whole rock analyses were determined
Gallium Deposits in the United States
This U.S. Geological Survey (USGS) data release provides the descriptions of the only U.S. sites—including mineral regions, mineral occurrences, and mine features—that have reported production and (or) resources of gallium (Ga). The sites in this data release have contained resource and (or) past production of more than 16 metric tons Ga metal, which was the approximate average annual consumption
Tantalum Deposits in the United States
This U.S. Geological Survey (USGS) data release provides the descriptions of the only U.S. sites--including mineral regions, mineral occurrences, and mine features--that have reported production and (or) resources of tantalum (Ta). The sites in this data release have contained resource and (or) past production of more than 900 metric tons Ta metal, which was the approximate average annual consumpt
Niobium Deposits in the United States
This U.S. Geological Survey (USGS) data release provides the descriptions of 11 U.S. sites that include mineral regions, mines, and mineral occurrences that contain enrichments of niobium (Nb). To be included in this data release, a site must have a contained resource and (or) past production of Nb metal greater than 10,000 metric tons, which was the approximate consumption of Nb in the U.S. in 20
Filter Total Items: 27
Annual review 2023: Critical minerals
No abstract available.
Authors
Graham W. Lederer, James V. Jones, Darcy McPhee, Jeffrey L. Mauk, Robert R. Seal, Kate M. Campbell, Jane M. Hammarstrom, Paul A. Bedrosian, Patricia Grace Macqueen, Garth E. Graham, Federico Solano, George N. D. Case, David George Pineault
Can the mining industry meet global demand for critical minerals?
No abstract available.
Authors
Jeffrey L. Mauk, Jonathan Andrew Funk, Nick Karl
Mineralogical, magnetic and geochemical data constrain the pathways and extent of weathering of mineralized sedimentary rocks
The oxidative weathering of sulfidic rock can profoundly impact watersheds through the resulting export of acidity and metals. Weathering leaves a record of mineral transformation, particularly involving minor redox-sensitive phases, that can inform the development of conceptual and quantitative models. In sulfidic sedimentary rocks, however, variations in depositional history, diagenesis and mine
Authors
Sergio Carrero, Sarah P. Slotznick, Sirine C. Fakra, M. Cole Sitar, Sharon E. Bone, Jeffrey L. Mauk, Andrew H. Manning, Nicholas L. Swanson-Hysell, Kenneth H. Williams, Jillian F. Banfield, Benjamin Gilbert
USGS Critical Minerals Review: 2021
In 2021, the U.S. Geological Survey (USGS) continued to play a central role in understanding and anticipating potential supply chain disruptions by defining and quantitatively evaluating mineral criticality. In addition, the USGS continued to evaluate new sources of domestic critical minerals by conducting mineral resource assessments, mapping and surveying regions prospective for critical minera
Authors
Steven M. Fortier, Nedal T. Nassar, Garth E. Graham, Jane M. Hammarstrom, Warren C. Day, Jeffrey L. Mauk, Robert R. Seal
USGS 2020 critical minerals review
Concerns about the lack of domestic production and availability of essential mineral raw materials were a recurring theme throughout the 20th century, particularly in the periods around armed conflicts (Congressional Research Service, 2019). These concerns resulted in the designation of particular minerals as “strategic” or “critical,” terms that commonly depend on the perspective of the user, but
Authors
Steven M. Fortier, Nedal T. Nassar, Karen D. Kelley, Graham W. Lederer, Jeffrey L. Mauk, Jane M. Hammarstrom, Warren C. Day, Robert R. Seal
The critical minerals initiative of the U.S. Geological Survey’s mineral deposit database project: USMIN
The objective of the US Geological Survey’s mineral deposit database project (USMIN) is to develop a comprehensive twenty-first century geospatial database that is the authoritative source of the most important mines, mineral deposits, and mineral districts of the US. Since May 2017, the project has focused on critical minerals. Data for critical minerals that are produced as products are relative
Authors
Jeffrey L. Mauk, Nick A Karl, Carma A. San Juan, Liam Dandurand Knudsen, German Schmeda, Clayton Robert Forbush, Bradley S. Van Gosen, Morgan Mullins, Patrick Christopher Scott
Pyrrhotite distribution in the conterminous United States, 2020
In parts of Connecticut and Massachusetts, foundations of some homes are cracking and crumbling. Failing foundations can reduce the market value of a home and lifting a house to replace and repour a foundation is an expensive undertaking. In response, some homeowners are defaulting on their mortgages and abandoning their homes. The culprit is pyrrhotite, which occurs in construction aggregate (cru
Authors
Jeffrey L. Mauk, Thomas C. Crafford, John D. Horton, Carma A. San Juan, Gilpin R. Robinson,
Descriptive models for epithermal gold-silver deposits
Epithermal gold-silver deposits are vein, stockwork, disseminated, and replacement deposits that are mined primarily for their gold and silver contents; some deposits also contain substantial resources of lead, zinc, copper, and (or) mercury. These deposits form in the uppermost parts of the crust, at depths less than about 1,500 meters below the water table, and at temperatures below about 300 °C
Authors
David A. John, Peter G. Vikre, Edward A. du Bray, Richard J. Blakely, David L. Fey, Barnaby W. Rockwell, Jeffrey L. Mauk, Eric D. Anderson, Frederick Graybeal
By
Ecosystems Mission Area, Energy Resources Program, Mineral Resources Program, National Laboratories Program, Science and Decisions Center, Geology, Geophysics, and Geochemistry Science Center, Geology, Minerals, Energy, and Geophysics Science Center, Western Fisheries Research Center, Central Energy Resources Science Center
Element partitioning in magnetite under low-grade metamorphic conditions – A case study from the Proterozoic Belt Supergroup, USA
The distribution and partitioning of elements in igneous rocks is well established for various melt –(fluid) –solid pairs and provides important insights into the petrogenesis of these rocks. Studies of the partitioning behavior of elements under metamorphic conditions are scarce and commonly focus on high-grade metamorphic facies. Little is known about the partitioning behavior of elements under
Authors
Patrick Nadoll, Jeffrey L. Mauk, Timothy Hayes, Alan Koenig, Stephen E. Box
Sedimentology, sequence-stratigraphy, and geochemical variations in the Mesoproterozoic Nonesuch Formation, northern Wisconsin, USA
We use core descriptions and portable X-ray fluorescence analyses to identify lithofacies and stratigraphic surfaces for the Mesoproterozoic Nonesuch Formation within the Ashland syncline, Wisconsin. We group lithofacies into facies associations and construct a sequence stratigraphic framework based on lithofacies stacking and stratigraphic surfaces. The fluvial-alluvial facies association (upper
Authors
Esther Kingsbury Stewart, Jeffrey L. Mauk
Constraining the thermal history of the North American Midcontinent Rift System using carbonate clumped isotopes and organic thermal maturity indices
The Midcontinent Rift System (MRS) is a Late Mesoproterozoic (∼1.1 Ga) sequence of volcanic and sedimentary rocks exposed in the Lake Superior Region of North America. The MRS continues to be the focus of much research due to its economic mineral deposits as well as its archive of Precambrian life and tectonic processes. In order to constrain the post-depositional thermal history of the MRS, sampl
Authors
Timothy M. Gallagher, Nathan D. Sheldon, Jeffrey L. Mauk, Sierra V. Petersen, Nur Gueneli, Jochen J. Brocks
Episodic formation of the world-class Waihi epithermal Au-Ag vein system, Hauraki Goldfield, New Zealand
The world-class Waihi vein system in New Zealand has produced more than 248,400 kg Au and 1.43 million kg Ag. New high-precision 40Ar/39Ar dates of adularia from different veins show that some veins formed at different times (6.15 Ma Martha vs. 5.83 and 5.85 Ma Empire and Welcome, respectively), even though they have similar mineralogy. The Martha vein formed over a period of approximately 150,000
Authors
Erin Gasston, Jeffrey L. Mauk, Michael A. Cosca, Leah E. Morgan, Chris M. Hall
Science and Products
USMIN Mineral Deposit Database
Our objective is to develop a national-scale, geospatial database that is the authoritative source of the most important mines, mineral deposits, and mineral districts of the United States.
Sediment-Hosted Copper Deposits in the Lake Superior Portion of the Midcontinent Rift System
This project is focused on the sediment-hosted copper deposits of the Midcontinent Rift, with three main objectives: 1) describe the ore mineralogy and geochemistry of the White Pine and Copperwood deposits, 2) evaluate whether hydrothermal alteration in footwall rocks can be used as a vector towards ore, and 3) provide a careful scoping study to evaluate whether unconventional platinum-group...
Filter Total Items: 20
GIS Data for Geologic Maps of Ravalli Group and other Mesoproterozoic Belt Supergroup Strata Based on Mapping by ASARCO in Northern Idaho and Northwestern Montana
The data release for geologic maps of Ravalli Group and other Mesoproterozoic Belt Supergroup strata in northern Idaho and northwestern Montana is a digital, Geologic Map Schema (GeMS)-compliant version of maps published in U.S. Geological Survey (USGS) Open-File Report 2001-438 (Boleneus and others, 2001). The new digital data present attribute tables and geospatial features (points, lines, and p
The major, minor, and trace element geochemistry of mineral scales from The Geysers geothermal field, California, USA
This data release provides quantitative whole rock geochemical results from The Geysers vapor-dominated geothermal field in California. The concentrations of major elements are reported in oxide weight percent by wavelength dispersive x-ray fluorescence (WDXRF), the concentrations for sixty elements are reported in elemental weight percent (pct) or parts per million (ppm) from inductively coupled
Semiquantitative mineralogy results from powder X-ray diffraction (XRD) analyses of mineral scales from The Geysers geothermal field, California, USA
This data release provides semiquantitative mineralogy results from X-ray diffraction (XRD) analyses of mineral scales from The Geysers vapor-dominated geothermal field in California. The mineral species and their abundances are reported in weight percent and values have been normalized to total 100 percent for each sample. The X-ray diffraction results show that the mineral samples from the wellh
Indium deposits in the United States
This U.S. Geological Survey (USGS) data release provides the descriptions of the only U.S. sites-including mining districts, mineral occurrences, and mine features-that have reported production and (or) resources of indium (In). This dataset contains the Bingham and West Desert deposits in Utah, and the Chino site in New Mexico.
Indium is considered a critical and strategic mineral because of its
Whole rock major, minor, and trace element geochemistry of the upper part of the Mount Emmons-Redwell porphyry molybdenum (Climax-type) deposit, Redwell Basin, Crested Butte, Colorado
This U.S. Geological Survey (USGS) data release provides whole rock major, minor, and trace element geochemical data from the fluorine-rich Mount Emmons-Redwell porphyry molybdenum (Climax-type) deposit (Mt. Emmons-Redwell deposit), located approximately 5.6 km (3.5 mi) northwest of Crested Butte, Colorado. The Mt. Emmons-Redwell deposit partly underlies Redwell Basin on the northwest flank of Mou
Graphite deposits in the United States
This U.S. Geological Survey (USGS) data release provides the descriptions of 10 U.S. sites that include mineral regions, mineral occurrences, and mine features that contain enrichments of graphite. To be included in this data release, sites must have a contained resource and (or) past production of more than 1,000 metric tons of graphite, which is approximately 3 percent of the average annual U.S.
Table of Electron Probe Microanalyses of Native Copper and Sulfide Minerals from the White Pine Sediment-hosted Copper Deposit, Michigan
This data release provides electron microprobe geochemical data that was collected as part of a scoping study to evaluate whether unconventional critical element resources may be associated with sediment-hosted copper systems in the Midcontinent Rift. We report abundances of trace elements in native copper and sulfide minerals in 12 thin sections from samples of the Mesoproterozoic lower Nonesuch
Hydrologic and geophysical data from high-elevation boreholes in Redwell Basin near Crested Butte, Colorado
Four boreholes (MW1, MW1UZ, MW2, MW2.1) were drilled in the fall of 2017 and summer of 2018 in upper Redwell Basin, a headwater catchment underlain by hydrothermally altered sedimentary rock in the Elk Mountains near the town of Crested Butte, Colorado. The boreholes were continuously cored using a wireline HQ-sized coring system and sample a combination of Quaternary-aged surficial colluvium and
Multi-element geochemical analyses of samples from the Mesoproterozoic Nonesuch Formation and Copper Harbor Conglomerate at the Copperwood copper deposit, Western Syncline, Michigan, USA
This data release provides multi-element data for drill core samples from the Mesoproterozoic Nonesuch Formation and Copper Harbor Conglomerate at the Copperwood copper deposit, Michigan, USA. Copper was determined by assay, and sulfur by inductively coupled plasma-optical emission spectrometry (ICP-OES) after aqua regia digestion for most samples. Multi-element whole rock analyses were determined
Gallium Deposits in the United States
This U.S. Geological Survey (USGS) data release provides the descriptions of the only U.S. sites—including mineral regions, mineral occurrences, and mine features—that have reported production and (or) resources of gallium (Ga). The sites in this data release have contained resource and (or) past production of more than 16 metric tons Ga metal, which was the approximate average annual consumption
Tantalum Deposits in the United States
This U.S. Geological Survey (USGS) data release provides the descriptions of the only U.S. sites--including mineral regions, mineral occurrences, and mine features--that have reported production and (or) resources of tantalum (Ta). The sites in this data release have contained resource and (or) past production of more than 900 metric tons Ta metal, which was the approximate average annual consumpt
Niobium Deposits in the United States
This U.S. Geological Survey (USGS) data release provides the descriptions of 11 U.S. sites that include mineral regions, mines, and mineral occurrences that contain enrichments of niobium (Nb). To be included in this data release, a site must have a contained resource and (or) past production of Nb metal greater than 10,000 metric tons, which was the approximate consumption of Nb in the U.S. in 20
Filter Total Items: 27
Annual review 2023: Critical minerals
No abstract available.
Authors
Graham W. Lederer, James V. Jones, Darcy McPhee, Jeffrey L. Mauk, Robert R. Seal, Kate M. Campbell, Jane M. Hammarstrom, Paul A. Bedrosian, Patricia Grace Macqueen, Garth E. Graham, Federico Solano, George N. D. Case, David George Pineault
Can the mining industry meet global demand for critical minerals?
No abstract available.
Authors
Jeffrey L. Mauk, Jonathan Andrew Funk, Nick Karl
Mineralogical, magnetic and geochemical data constrain the pathways and extent of weathering of mineralized sedimentary rocks
The oxidative weathering of sulfidic rock can profoundly impact watersheds through the resulting export of acidity and metals. Weathering leaves a record of mineral transformation, particularly involving minor redox-sensitive phases, that can inform the development of conceptual and quantitative models. In sulfidic sedimentary rocks, however, variations in depositional history, diagenesis and mine
Authors
Sergio Carrero, Sarah P. Slotznick, Sirine C. Fakra, M. Cole Sitar, Sharon E. Bone, Jeffrey L. Mauk, Andrew H. Manning, Nicholas L. Swanson-Hysell, Kenneth H. Williams, Jillian F. Banfield, Benjamin Gilbert
USGS Critical Minerals Review: 2021
In 2021, the U.S. Geological Survey (USGS) continued to play a central role in understanding and anticipating potential supply chain disruptions by defining and quantitatively evaluating mineral criticality. In addition, the USGS continued to evaluate new sources of domestic critical minerals by conducting mineral resource assessments, mapping and surveying regions prospective for critical minera
Authors
Steven M. Fortier, Nedal T. Nassar, Garth E. Graham, Jane M. Hammarstrom, Warren C. Day, Jeffrey L. Mauk, Robert R. Seal
USGS 2020 critical minerals review
Concerns about the lack of domestic production and availability of essential mineral raw materials were a recurring theme throughout the 20th century, particularly in the periods around armed conflicts (Congressional Research Service, 2019). These concerns resulted in the designation of particular minerals as “strategic” or “critical,” terms that commonly depend on the perspective of the user, but
Authors
Steven M. Fortier, Nedal T. Nassar, Karen D. Kelley, Graham W. Lederer, Jeffrey L. Mauk, Jane M. Hammarstrom, Warren C. Day, Robert R. Seal
The critical minerals initiative of the U.S. Geological Survey’s mineral deposit database project: USMIN
The objective of the US Geological Survey’s mineral deposit database project (USMIN) is to develop a comprehensive twenty-first century geospatial database that is the authoritative source of the most important mines, mineral deposits, and mineral districts of the US. Since May 2017, the project has focused on critical minerals. Data for critical minerals that are produced as products are relative
Authors
Jeffrey L. Mauk, Nick A Karl, Carma A. San Juan, Liam Dandurand Knudsen, German Schmeda, Clayton Robert Forbush, Bradley S. Van Gosen, Morgan Mullins, Patrick Christopher Scott
Pyrrhotite distribution in the conterminous United States, 2020
In parts of Connecticut and Massachusetts, foundations of some homes are cracking and crumbling. Failing foundations can reduce the market value of a home and lifting a house to replace and repour a foundation is an expensive undertaking. In response, some homeowners are defaulting on their mortgages and abandoning their homes. The culprit is pyrrhotite, which occurs in construction aggregate (cru
Authors
Jeffrey L. Mauk, Thomas C. Crafford, John D. Horton, Carma A. San Juan, Gilpin R. Robinson,
Descriptive models for epithermal gold-silver deposits
Epithermal gold-silver deposits are vein, stockwork, disseminated, and replacement deposits that are mined primarily for their gold and silver contents; some deposits also contain substantial resources of lead, zinc, copper, and (or) mercury. These deposits form in the uppermost parts of the crust, at depths less than about 1,500 meters below the water table, and at temperatures below about 300 °C
Authors
David A. John, Peter G. Vikre, Edward A. du Bray, Richard J. Blakely, David L. Fey, Barnaby W. Rockwell, Jeffrey L. Mauk, Eric D. Anderson, Frederick Graybeal
By
Ecosystems Mission Area, Energy Resources Program, Mineral Resources Program, National Laboratories Program, Science and Decisions Center, Geology, Geophysics, and Geochemistry Science Center, Geology, Minerals, Energy, and Geophysics Science Center, Western Fisheries Research Center, Central Energy Resources Science Center
Element partitioning in magnetite under low-grade metamorphic conditions – A case study from the Proterozoic Belt Supergroup, USA
The distribution and partitioning of elements in igneous rocks is well established for various melt –(fluid) –solid pairs and provides important insights into the petrogenesis of these rocks. Studies of the partitioning behavior of elements under metamorphic conditions are scarce and commonly focus on high-grade metamorphic facies. Little is known about the partitioning behavior of elements under
Authors
Patrick Nadoll, Jeffrey L. Mauk, Timothy Hayes, Alan Koenig, Stephen E. Box
Sedimentology, sequence-stratigraphy, and geochemical variations in the Mesoproterozoic Nonesuch Formation, northern Wisconsin, USA
We use core descriptions and portable X-ray fluorescence analyses to identify lithofacies and stratigraphic surfaces for the Mesoproterozoic Nonesuch Formation within the Ashland syncline, Wisconsin. We group lithofacies into facies associations and construct a sequence stratigraphic framework based on lithofacies stacking and stratigraphic surfaces. The fluvial-alluvial facies association (upper
Authors
Esther Kingsbury Stewart, Jeffrey L. Mauk
Constraining the thermal history of the North American Midcontinent Rift System using carbonate clumped isotopes and organic thermal maturity indices
The Midcontinent Rift System (MRS) is a Late Mesoproterozoic (∼1.1 Ga) sequence of volcanic and sedimentary rocks exposed in the Lake Superior Region of North America. The MRS continues to be the focus of much research due to its economic mineral deposits as well as its archive of Precambrian life and tectonic processes. In order to constrain the post-depositional thermal history of the MRS, sampl
Authors
Timothy M. Gallagher, Nathan D. Sheldon, Jeffrey L. Mauk, Sierra V. Petersen, Nur Gueneli, Jochen J. Brocks
Episodic formation of the world-class Waihi epithermal Au-Ag vein system, Hauraki Goldfield, New Zealand
The world-class Waihi vein system in New Zealand has produced more than 248,400 kg Au and 1.43 million kg Ag. New high-precision 40Ar/39Ar dates of adularia from different veins show that some veins formed at different times (6.15 Ma Martha vs. 5.83 and 5.85 Ma Empire and Welcome, respectively), even though they have similar mineralogy. The Martha vein formed over a period of approximately 150,000
Authors
Erin Gasston, Jeffrey L. Mauk, Michael A. Cosca, Leah E. Morgan, Chris M. Hall