Browsing by Author "Hudak, George J"

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    Bedrock Geologic Map of the Disappointment and Ima Lakes Area, Lake County, Northeastern Minnesota
    (2008-08) Stifter, Eric; Wartman, Jakob; Gibbons, Jack; Kane, Kevin; Murphy, Laura; Carlson, Anders; Mason, Tracey; Hudak, George J; Peterson, Dean M
    This map is the result of seven days of field mapping by the authors in 2008, as well as a compilation of information gathered from Van Hise (1901), Gruner (1941), and Chandler (1991). This map was created by PRC Field Camp students under the supervision and guidance of Dr. Dean Peterson, NRRI Senior Research Associate, and Dr. George Hudak, professor at UW-Oshkosh. The purpose of this map is to aid in understanding the nature of the basal contact between the Duluth Complex and Wawa Subprovince Archean metavolcanic-metasedimentary rocks, which was last mapped in the early 1940's. Additionally, this map will serve as a basis for additional undergraduate honors theses studies. Access to the 663 outcrops mapped for this project was provided by extensive canoe shoreline mapping and traverses in the blown-down bush of the Dissapointment and Ima Lakes field area. This map was made at a 1:10,000 scale, and is the first detailed map done in an area previously mapped on a reconnaissance scale.
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    Bedrock Geologic Map of the Disappointment Lake Area, Lake County, Northeastern Minnesota
    (2009-08) Mulvey, Lucy; Ross, Cabin; Zeitler, Joseph; Pendleton, Matthew; McCarthy, Andrew; Copp, Lee; Nowak, Robert; Hudak, George J; Peterson, Dean M
    This map was created by PRC Field Camp students under the guidance of Dr. Dean Peterson, Duluth Metals Limited Senior Vice President of Exploration, and Dr. George Hudak, Associate Professor of Geology at the University of Wisconsin Oshkosh. The purpose of this map is to further understand the relationship between the Duluth Complex and the older Archean metasediment, volcanic and volcaniclastic rocks in the area which were last mapped in the early 1940's by Gruner. This map will also facilitate undergraduate research theses studies. This map is the result of seven days of field mapping by the authors in 2009. Access to the 955 outcrops included in this project was achieved through extensive mapping of shorelines within the Disappointment, Parent and Snowbank Lakes field area combined with multiple traverses through dense bush and swamp areas. This is the first detailed map of the area produced at a 1:10,000 scale.
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    Bedrock Geologic Map of the Putnam Lake Area, St. Louis County, Northeastern Minnesota
    (2012-08) Fehrs, Ellen; Kenny, Edward; Kuchma, John; Sauer, Sarah; Sylvester, William; Hudak, George J
    This map was created by five students of the Precambrian Research Center under the guidance of Dr. George Hudak, Senior Research Associate at the Natural Resources Research Institute and Associate Director of the PRC. The map was produced from detailed (1:5000 scale) geological field mapping between August 6 and August 11, 2012. The resulting geological map is projected using a Universal Transverse Mercator (UTM) Grid, Zone 15, using the North American Datum of 1983 (NAD83). Base map LIDAR imagery, topographic contour lines, administrative boundaries, and hydrologic features were obtained as digital files from the Minnesota Department of Natural Resources Data Deli (http://deli.dnr. state.mn.us/) and the Minnesota Geospatial Information Office (http://www.mngeo.state.mn.us/chouse/elevation/lidar.html). A series of logging roads and trails provided access to the state public lands which were mapped during this exercise. This mapping was performed to: 1) conduct detailed property-scale mapping on the southwestern side of the Tower-Soudan Anticline which, to date, has only been mapped on a regional scale; 2) evaluate the supracrustal stratigraphy on the south side of the Tower-Soudan anticline, and try to make further correlations between stratigraphic units on the north side and southwest sides of the Tower-Soudan anticline; 3) to explore for evidence of syn-volcanic and/or post-volcanic hydrothermal alteration and associated mineralization in the eld area; and 4) evaluate the utility of using LIDAR basemaps for detailed geological mapping in heavily forested regions of greenstone belt terranes. Taken together, this mapping was performed to provide additional detail to existing regional geological maps of the Vermilion District (for example Peterson and Jirsa, 1999 and Peterson, 2005).
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    Bedrock Geology Map of the Footwall of the Soudan Iron Formation South of Twin Lakes, St. Louis County, Northeastern Minnesota
    (2007-08) Moosavi, Sadedin; Johnson, Tom; Wendland, Corey; Anderson, Ashley; Hudak, George J
    This map is one of four maps produced from the capstone project of the Precambrian Research Center Field Mapping Course during the summer of 2007. Publication of this map is the beginning of a planned series of detailed maps of the Precambrian Crustal Terrain of northeastern Minnesota. Efforts to obtain this map information were conducted in association with the University of Minnesota-Duluth, Precambrian Research Center and the Natural Resources Research Institute. Such mapping will help aid in the exploration for VMS-style mineralization deposits as well as provide a better understanding of the Twin Lakes supracrustal volcanic stratigraphy. Prior to this project, the geology of the Twin Lakes area was inferred from other published maps. The first of these publications describing the geology in the Twin Lakes area was included in the larger scale regional map of the Lower Ely Greenstone Member, (Sims and Southwick, 1985). Additional mapping and compilation of exploratory data collected by Bear Creek Mining (during the 1960's) was included in a later publication compiled by D. Peterson and M. Jirsa, 1999. Recent mapping by the authors was concentrated in the Twin Lakes region at a scale of 1:5000. The authors mapped 300 outcrops in an area covering approximately 260 hectares south of Twin Lakes. The authors believe that further geological studies (i.e. additional field mapping, petrographic studies, and lithogeochemical studies) should be completed to better constrain the geological and geochemical processes that occurred during the evolution of both the supracrustal and intrusive strata in the Twin Lakes area. Such studies will assist in unambiguously determining the correlations between the geology of the western and eastern parts of the Vermillion District.
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    Bedrock Geology of Lake Vermilion/Soudan Underground Mine State Park
    (University of Minnesota Duluth, 2016-06) Radakovich, Amy; Pignotta, Geoff; Schwierske, Kelly; Students from the 2010-2013 Precambrian Research Center Geology Field Camp; Hudak, George J; Peterson, Dean M
    Lake Vermilion/Soudan Underground Mine State Park possesses a rich cultural and natural history that is directly related to the bedrock geology in this part of Minnesota’s Vermilion District. The bedrock geology comprises a complex record of Neoarchean-age (>2.5 billion years old) volcanic, sedimentary, hydrothermal, structural, and tectonic events associated with the Wawa-Abitibi Terrane within the southwestern part of the Superior Craton (Stott et al., 2007; Stott and Mueller, 2009; Lodge et al., 2013, 2015). Considerable geological research has been conducted since the late 1990s to study the stratigraphy, hydrothermal alteration, structural geology, and economic geology in the Vermilion District (Lawler and Riihilouma, 1997; Hudak and Morton, 1999; Peterson and Jirsa, 1999; Hovis, 2001; Jirsa et al., 2001; Newkirk et al., 2001; Odette et al., 2001; Peterson, 2001, 2005; Peterson et al., 2001; Hudak et al., 2002a, 2002b, 2006, 2007, 2012; Hocker et al., 2003; Peterson and Patelke, 2003; Hoffman, 2007; Jansen et al., 2009; Lodge et al. 2013, 2015). As well, numerous geological field trips have been conducted in this region since the mid-2000s (Hudak et al., 2004, 2014; Jirsa et al., 2004, 2016; Larson and Mooers, 2009; Peterson and Patelke, 2004; Peterson et al., 2009a, 2009b). Although several regional scale geologic maps exist for regions encompassing, and in close proximity to, Lake Vermilion/Soudan Underground Mine State Park (Ojakangas et al., 1978; Sims and Southwick, 1980, 1985; Sims, 1985; Southwick, 1993; Peterson and Jirsa, 1999; Jirsa et al., 2001; Peterson and Patelke, 2003; Hudak et al., 2002b; Hoffman, 2007), no coherent, detailed (1:10,000 scale) geologic map exists for the region comprising Minnesota’s newest state park. Minnesota Department of Natural Resources Parks and Trails staff have partnered with the Precambrian Research Center (PRC) at the Natural Resources Research Institute (NRRI) at the University of Minnesota Duluth to conduct geologic mapping in Lake Vermilion/Soudan Underground Mine State Park since 2010. This partnership had two primary goals: 1) to offer a collaborative opportunity to train upper-level undergraduate and graduate university geology students effective and efficient methods to conduct geologic mapping in Precambrian terranes; and 2) through geologic mapping, gain a deeper understanding of the geological processes and events associated with the development of the Vermilion District within the context of the larger Wawa-Abitibi Terrane. This partnership has led to the development of a new geologic map for Lake Vermilion/Soudan Underground Mine State Park (Peterson et al., 2016) which this report describes.
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    Bench-Scale Evaluation of Hydrometallurgical Processing to Recover Vanadium from Minnesota Titanium Resources
    (University of Minnesota Duluth, 2021-10) Hudak, George J; Monson Geerts, Stephen D; Chen, Jonathan; Halim, A; Sridhar, Ram; Lakshmanan, V.I.
    Vanadium is the twenty-second most abundant element in the Earth’s crust and occurs as a major component (greater than 10% by weight) in 156 minerals that occur in a variety of mineral deposit types. These mineral deposit types are globally distributed and include vanidiferous titanomagnetite (VTM) deposits, sandstone hosted (SSV) deposits, shale-hosted vanadium deposits, and vanadate deposits (Kelley et al., 2017). The Duluth Complex of northeastern Minnesota contains a variety of base and precious metal resources (Fig. 1), including a number of Mesoproterozoic-age copper-nickel-cobalt-platinum group element (Cu-Ni-Co-PGE) resources as well as a series of younger, Mesoproterozoic-age oxide ultramafic intrusions (OUIs) that contain both titanium and vanadium resources (Minnesota Minerals Coordinating Committee, 2016; Table 1). Vanadium deposits within OUI deposits associated with the Duluth Complex are classified as vanadiferous titanomagnetite (VTM-type) vanadium deposits by the United States Geological Survey (USGS; Kelley et al., 2017). World resources of vanadium are greater than 63 million tons; however, vanadium concentrations generally constitute less than 2% of the deposit host rock (Polyak, 2021). In 2020, mine production of vanadium worldwide was approximately 94,800 tons, with the United States (0.2%), Brazil (7.7%), China (61.6%), Russia (21.0%) and South Africa (9.5%) being the major producers (Polyak, 2021). Vanadium is utilized in a variety of applications. Its principal use is for the production of metal alloys such as high-strength steel and alloys utilized in the aerospace industry. It is also used for catalysts in the chemical industry, in ceramics, in glasses, and as a pigment (Schulz et al., 2017). Production of carbon-, full-alloy-, and high-strength low-alloy steels accounted for 18%, 45%, and 33% of domestic consumption in 2020, respectively (Polyak, 2021). The emerging need for large-scale “green” electrical energy storage associated with wind, solar, and other intermittent power sources may result in major utilization of vanadium in the form of vanadium redox-flow batteries (VFRB) which take advantage of the various electrical valencies of vanadium cations (https://energystorage.org/why-energy-storage/technologies/vanadium-redox-vrb-flow-batteries/). As well, vanadium is utilized in other battery applications, including lithium-vanadium-phosphate batteries and lithium ion batteries (Schulz et al., 2017). Commercial products resulting from processing of vanadium ores include ferrovanadium (FeV, an iron-vanadium alloy), which is used in the production of steel alloys, vanadium pentoxide (V2O5), which is commonly utilized as a chemical catalyst, and ammonium metavanadate (NH4VO3), a precursor for the production of vanadium pentoxide, catalysts, and analytical reagents (Pérez-Benítez and Bernès, 2018). In 2020, U.S. net import reliance for vanadium was 96%, with major import sources being Brazil, South Africa, Austria and Canada (United States Geological Survey, 2021). A large portion of domestic needs could be met by domestic resources and secondary recovery processes (Polyak, 2021). As a result of this large net import reliance, vanadium is considered a critical mineral resource in the United States (Executive Order 13817 “Federal Strategy to Ensure Reliable Supplies of Critical Metals”; Schulz et al., 2017; Nassar and Fortier, 2021). Results of recent hydrometallurgical experiments conducted by Process Research Ortech (PRO) and the Natural Resources Research Institute (NRRI) indicate that vanadium concentrations continue to increase within titanium raffinate as recycling of organics takes place in a closed-system hydrometallurgical circuit developed to produce TiO2 and Fe2O3 products from the Longnose OUI mineral deposit (Hudak et al., 2021). The research described in this report discusses collaborative research conducted by PRO and NRRI to evaluate whether or not high-purity vanadium materials (specifically ammonium metavanadate and vanadium pentoxide) could be produced as by-products of hydrometallurgical processing of the titanium raffinate solutions resulting from continuous pilot-scale hydrometallurgical processing of Longnose mineral concentrates (Hudak et al., 2021).
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    A Bibliography of Published Research in Minnesota Related to the State’s Mineral Potential: April 2020
    (University of Minnesota Duluth, 2020-04) Hudak, George J
    The United States Geological Survey (USGS) provided funding via the FY 2019 National Geological and Geophysical Data Preservation Program (NGGDPP) for the project “Updated Minnesota Data Inventory: Preservation of Pillsbury Hall Rock Collections with Associated Additional Documentation: Assembly of Mineral Potential Related Information.” The three priority components of this project were as follows: • Priority 1: Collection Inventory and metadata record revision in the National Digital Catalog; • Priority 2: Preservation of Pillsbury Hall Rock collections with associated and additional documentation; and • Priority 3: Assemble information that supports identification of critical mineral resources in Minnesota. As part of Priority 3, the Natural Resources Research Institute (NRRI) was subcontracted by the Minnesota Geological Survey to prepare a bibliography briefly describing published research specific to Minnesota that supports inference of mineral potential on the basis of geological mapping, and a bibliography listing references for published literature on this topic. The NRRI provided matching funding to complete this work from the NRRI University of Minnesota Permanent University Trust Fund. The USGS has recently developed a new minerals system approach for critical minerals inventory, research and assessment (https://www.usgs.gov/energy-and-minerals/mineral-resourcesprogram/ science/systems-approach-critical-minerals-inventory?qt-science_center_objects=0#qtscience_ center_objects; Hostra, 2019). The following bibliography is organized utilizing this minerals system classification scheme. As Minnesota has a preserved geologic history that spans greater than 3.6 billion years, and as a wide variety of geological processes have been active over this geological history, mineral potential exists in many of the mineral systems, including Chemical Weathering, Placer, Meteoric Recharge, Marine Chemocline, Volcanogenic Seafloor, Orogenic, Metamorphic, IOA-IOCG, and Mafic Magmatic. As well, a short bibliography of potential By-Products/Recycling resources has been included with this bibliography.
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    A Bibliography of Published Research in Minnesota Related to the State’s Mineral Potential: June 2022
    (University of Minnesota Duluth, 2022-06) Hudak, George J
    The Minnesota Geological Survey (MGS) was provided funding from the United States Geological Survey (USGS) via the FY 2021 National Geological and Geophysical Data Preservation Program for the “FY21 Minnesota Geological and Geophysical Data Preservation Program.” The program included two priorities that collectively involved 11 separate Projects: Priority 1: Data Preservation • Project 1: Preservation of MGS Field Data • Project 2: Preservation of MGS Cuttings • Project 3: Minnesota Drill Core Library Inventory, Phase I • Project 4: Data Preservation Workshop Priority 2: Mineral Potential-Related Information • Project 5: State Compilation of Mineral Deposits / Districts • Project 6: Contribute Data to USGS Map Compilation of Focus Areas • Projects 7 and 8: State Compilation of Borehole Data with Metadata to NDC • Project 9: Update Geologic Map Database • Project 10: USGS Critical Minerals Workshop • Project 11: Strategic Plan for Critical Minerals As a Component of Priority 2, Project 6, “Contribute Data to USGS Map Compilation of Focus Areas,” the Natural Resources Research Institute (NRRI) was subcontracted by the Minnesota Geological Survey (MGS) to prepare a bibliography indicating published geological, geochemical, and geophysical research specific to Minnesota that supports inference of Mineral potential. Matching funding was provided from the NRRI University of Minnesota Permanent University Trust Fund to complete this work. The publications that form the basis of this bibliography are in NRRI Technical Summary Report “Duluth Complex Geological Bibliography” (Hauck, 2017), “A Bibliography of Published Research in Minnesota Related to the State’s Mineral Potential” (Hudak, 2020), and “Minnesota Data Preservation Report for 2019/2020: Updated Data Inventory, Preservation of Pillsbury Hall Rock Collections and Documentation, Assembly of Mineral Potential Related Information (Thorleifson, 2020). Matching funding was provided from the NRRI University of Minnesota Permanent University Trust Fund to complete this work. The following bibliography has been organized utilizing the USGS Mineral Systems approach for critical minerals inventory, research and assessment (Hofstra, 2019; Hofstra and Kreiner, 2020). As Minnesota has a preserved Geologic history that spans greater than 3.6 billion years, a wide variety of geological Processes encompassing a number of Mineral Systems have been active within the State. These include Chemical Weathering, Placer, Meteoric Recharge, Marine Chemocline, Volcanogenic Seafloor, Orogenic, Metamorphic, IOA-IOCG, and Mafic Magmatic. This bibliography includes references specific to each of these Mineral Systems, as well as a list of references Related to potential by-products, recycling, and carbon Mineralization publications focused on Minnesota resources.
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    A Bibliography of Published Research in Minnesota Related to the State’s Mineral Potential: June 2023
    (University of Minnesota Duluth, 2023-06) Hudak, George J
    The Minnesota Geological Survey (MGS) was provided funding from the United States Geological Survey (USGS) via the FY 2022 National Geological and Geophysical Data Preservation Program for the “FY22 Minnesota Geological and Geophysical Data Preservation Program.” The program included two priorities that collectively involved 10 separate projects: Priority 1: Data Preservation • Project 1: Preservation of MGS Field Data • Project 2: Seismic Database and Geophysical Compilation • Project 3: Preservation of MGS Cuttings, Phase Three • Project 4: Minnesota Drill Core Library Inventory, Phase Two • Project 5: Data Preservation Workshop Priority 2: Mineral Potential-Related Information • Project 6: State Compilation of Mineral Deposits / Districts • Project 7: Mapping for USGS Compilation of Earth MRI Focus Areas • Projects 8: State Compilation of Borehole Data • Project 9: Prepare For, and Attend, and Follow-Up Earth MRI Workshop • Project 10: Preservation Plan for Critical Minerals As a Component of Priority 2, Project 7, “Mapping for USGS Compilation of Earth MRI Focus Areas,” the Natural Resources Research Institute (NRRI) was subcontracted by the Minnesota Geological Survey (MGS) to prepare a bibliography indicating published geological, geochemical, and geophysical research specific to Minnesota that supports inference of Mineral potential. Matching funding was provided from the NRRI University of Minnesota Permanent University Trust Fund to complete this work. The publications that form the basis of this bibliography are included in NRRI Technical Summary Report “Duluth Complex Geological Bibliography” (Hauck, 2017), “A Bibliography of Published Research in Minnesota Related to the State’s Mineral Potential” (Hudak, 2020), “Minnesota Data Preservation Report for 2019/2020: Updated Data Inventory, Preservation of Pillsbury Hall Rock Collections and Documentation, Assembly of Mineral Potential Related Information” (Thorleifson, 2020), and “A Bibliography of Published Research in Minnesota Related to the State’s Mineral Potential: June 2022” (Hudak, 2022). The following bibliography has been organized utilizing the USGS Mineral Systems approach for critical minerals inventory, research and assessment (Hofstra, 2019; Hofstra and Kreiner, 2020). As Minnesota has a preserved geologic history that spans greater than 3.6 billion years, a wide variety of geological processes encompassing several mineral systems have been active within the State. These include Chemical Weathering, Placer, Meteoric Recharge, Marine Chemocline, Volcanogenic Seafloor, Orogenic, Metamorphic, IOA-IOCG, and Mafic Magmatic. This bibliography includes references specific to each of these mineral systems, as well as a list of references related to potential by-products, recycling, and carbon mineralization publications focused on—and/or referencing—Minnesota resources.
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    Comparative Geology, Stratigraphy, and Lithogeochemistry of the Five Mile Lake, Quartz Hill, and Skeleton Lake VMS Occurrences, Western Vermilion District, NE Minnesota
    (University of Minnesota Duluth, 2002-12) Hudak, George J; Heine, John J; Newkirk, Trent; Odette, Jason; Hauck, Steven A
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    Continuous Pilot-Scale Demonstration of Ilmenite Processing Technology
    (University of Minnesota Duluth, 2021-05) Hudak, George J; Rao, Shashi; Peterson, Dean M; Chen, Jonathan; Lakshmanan, V.I.; Sridhar, Ram; Gluck, Eugen
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    Electron Microprobe Analysis of Alteration Mineralogy at the Archean Five Mile Lake Volcanic Associated Massive Sulfide Mineral Prospect in the Vermilion District of Northeastern Minnesota
    (University of Minnesota Duluth, 2003-05) Hocker, Stephanie M; Hudak, George J; Heine, John J
    Alteration mineral assemblage mapping at the Five Mile Lake Prospect in the Vermilion District of northeastern Minnesota has identified two distinct types of alteration zones within 2.7 billion year-old volcanic and volcaniclastic rocks associated with volcanic-hosted massive sulfide (VHMS) mineralization (Hudak et al., in press; Odette et al., 2001a, 2001b; Peterson, 2001). Regional semi-conformable alteration zones are composed of various proportions of quartz + epidote ± amphibole ± chlorite ± plagioclase feldspar. These regional, semiconformable alteration zones are locally crosscut by several relatively narrow, northeasttrending disconformable alteration zones composed of fine-grained chlorite and/or sericite that are closely associated with synvolcanic fault zones. Electron microprobe analyses of the various alteration mineral phases (epidote group minerals, chlorite, amphibole, white mica, and feldspar) have been conducted in an effort to better understand the hydrothermal processes associated with the development of the semiconformable and disconformable alteration zones at the Five Mile Lake Prospect. These analyses indicate that: a) epidote group minerals range in composition from zoisite/clinozoisite to pistacite; b) chlorite is dominantly ripidolite; c) amphibole is primarily actinolite and ferroactinolite, with magnesio-hornblende and ferro-hornblende also present; d) sericite is finegrained muscovite; and e) feldspar is albite. This mineral chemistry suggests the presence of a complex, long-lived hydrothermal system that evolved from seafloor-proximal (hundreds of meters) to deeper subseafloor environments (~1-3 km) as the volcanic rocks were buried by rapid, dominantly effusive mafic to intermediate volcanism and associated sedimentation. Alteration mineral chemistry at the Five Mile Lake Prospect is remarkably similar to that from the Noranda VHMS mining camp of Canada as well as other VHMS orebodies. This mineral chemistry, combined with favorable volcanology and numerous untested geophysical targets, suggest that the Five Mile Lake Prospect, as well as the uppermost several hundred meters of the Lower Member of the Ely Greenstone, have excellent exploration potential for VHMS mineral deposits.
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    Electron Microprobe Analysis of Alteration Mineralogy at the Archean Five Mile Lake Volcanic Associated Massive Sulfide Mineral Prospect in the Vermilion District of Northeastern Minnesota
    (University of Minnesota Duluth, 2003-05) Hocker, Stephanie M; Hudak, George J; Heine, John J
    Alteration mineral assemblage mapping at the Five Mile Lake Prospect in the Vermilion District of northeastern Minnesota has identified two distinct types of alteration zones within 2.7 billion year-old volcanic and volcaniclastic rocks associated with volcanic-hosted massive sulfide (VHMS) mineralization (Hudak et al., in press; Odette et al., 2001a, 2001b; Peterson, 2001). Regional semi-conformable alteration zones are composed of various proportions of quartz + epidote ± amphibole ± chlorite ± plagioclase feldspar. These regional, semiconformable alteration zones are locally crosscut by several relatively narrow, northeast trending disconformable alteration zones composed of fine-grained chlorite and/or sericite that are closely associated with synvolcanic fault zones. Electron microprobe analyses of the various alteration mineral phases (epidote group minerals, chlorite, amphibole, white mica, and feldspar) have been conducted in an effort to better understand the hydrothermal processes associated with the development of the semiconformable and disconformable alteration zones at the Five Mile Lake Prospect. These analyses indicate that: a) epidote group minerals range in composition from oisite/clinozoisite to pistacite; b) chlorite is dominantly ripidolite; c) amphibole is primarily actinolite and ferroactinolite, with magnesio-hornblende and ferro-hornblende also present; d) sericite is finegrained muscovite; and e) feldspar is albite. This mineral chemistry suggests the presence of a complex, long-lived hydrothermal system that evolved from seafloor-proximal (hundreds of meters) to deeper subseafloor environments (~1-3 km) as the volcanic rocks were buried by rapid, dominantly effusive mafic to intermediate volcanism and associated sedimentation. Alteration mineral chemistry at the Five Mile Lake Prospect is remarkably similar to that from the Noranda VHMS mining camp of Canada as well as other VHMS orebodies. This mineral chemistry, combined with favorable volcanology and numerous untested geophysical targets, suggest that the Five Mile Lake Prospect, as well as the uppermost several hundred meters of the Lower Member of the Ely Greenstone, have excellent exploration potential for VHMS mineral deposits.
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    Geological Mapping of the Needleboy Lake – Six Mile Lake Area, Northeastern Minnesota: a Summary of Volcanogenic Massive Sulfide Potential
    (University of Minnesota Duluth, 2002-09) Hudak, George J; Heine, John J; Hocker, Stephanie M; Hauck, Steven A
    The Needleboy Lake and Six Mile Lake areas has focused on evaluating the stratigraphic succession, hydrothermal alteration, and synvolcanic and post-volcanic structures in an effort to better understand the VHMS potential in this region of the Lower Ely Greenstone. Field mapping in the Needleboy Lake area (performed during August, 2001) investigated all outcrops within a 100 to 200 meter perimeter of the Lake. A north-south section was also completed from the north-central shoreline of Five Mile Lake to the western shoreline of Needleboy Lake. Field mapping in the vicinity of Six Mile Lake (performed August-September, 2002) included three detailed north-south traverses (Fig. 4). Traverse 1 extended from the northwestern shoreline of Needleboy Lake to the western shoreline of Six Mile Lake. Traverse 2 extended from the northeastern shoreline of Needleboy Lake to approximately 200 meters north of Six Mile Lake. Traverse 3 extended from the southeastern part of Needleboy Lake to approximately 500 meters northeast of Six Mile Lake. In addition, all outcrops occurring along roads in the study area were investigated.
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    Minnesota Taconite Workers Health Study: Environmental Study of Airborne Particulate Matter - Development of Standard Operating Procedures for Particle Collection and Gravimetric Analysis
    (University of Minnesota Duluth, 2013-06) Monson Geerts, Stephen D; Hudak, George J; Marple, Virgil; Lundgren, Dale; Bernard, Olson; Bandli, Bryan; Brecke, Devon M
    Since late 2008, the Natural Resources Research Institute’s overall participation in the Minnesota Taconite Workers Health Study has been focused on the characterization of aerosol particulate matter on the Mesabi Iron Range in northeastern Minnesota. This study is formally known as the “Environmental Study of Airborne Particulates,” and it is one of five studies being conducted by the University of Minnesota School of Public Health and the Natural Resources Research Institute. An initial standard operating procedure (SOP) for particle sampling associated with the “Environmental Study of Airborne Particulates” was first developed through planning and collaboration with aerosol scientists at the University of Minnesota, Department of Mechanical Engineering. Since then, through additional experimentation and revisions, the original SOP sampling document has evolved into the comprehensive narrative that it is at present. This current document outlines a history of evolving in-house experiments and observations that ultimately resulted in the development of the SOP adopted by and practiced in the “Environmental Study of Airborne Particulates.” Equipment utilized in sample collection included the Micro-Orifice Uniform Deposition Impactor (MOUDI; Marple et al., 1991), a device which collects size-fractionated samples of particulate matter with aerodynamic diameters ranging from 30.0 to 0.056 microns, and a final filter that collects particles with aerodynamic diameters less than 0.056 microns. As well, a Total Filter Sampler (TFS), which collects all size fractions of particulate matter on a single substrate, was utilized so that particulate could be evaluated using Minnesota Department of Health analytical methods (Minnesota Department of Health Method 852). Results from the MOUDI sampling allow particulate matter (PM) to be classified into specific size classifications including: PM1, PM2.5 and PM10, which are important in assessing potential air quality measurements. As well, samples collected using the MOUDI sampler could be further evaluated using a wide variety of physical and chemical methods (for example, analysis using transmission and scanning electron microscopy, chemical analysis using proton induced X-ray emission analysis (PIXE)).
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    Minnesota Taconite Workers Health Study: Environmental Study of Airborne Particulate Matter in Mesabi Iron Range Communities and Taconite Processing Plants - A Characterization of the Mineral Component of Particulate Matter
    (University of Minnesota Duluth, 2019-12) Monson Geerts, Stephen D; Hudak, George J; Marple, Virgil; Lundgren, Dale; Zanko, Lawrence M; Olson, Bernard; Bandli, Bryan
    The Minnesota Taconite Workers Health Study (MTWHS) was initiated in 2008 and included a multicomponent study to further understand taconite worker health issues on the Mesabi Iron Range (MIR) in northeastern Minnesota. Approximately $4.9 million funding was provided by the Minnesota Legislature to conduct five separate studies related to this initiative, including:  An Occupational Exposure Assessment, conducted by the University of Minnesota School of Public Health (SPH);  A Mortality (Cause of Death) study, conducted by the University of Minnesota SPH;  Incidence studies, conducted by the University of Minnesota SPH;  A Respiratory Survey of Taconite Workers and Spouses, conducted by the University of Minnesota SPH; and  An Environmental Study of Airborne Particulate Matter, conducted by the Natural Resources Research Institute (NRRI) at the University of Minnesota Duluth (UMD). Results of the four studies conducted by the University of Minnesota SPH can be found on the Taconite Workers Health Study website (http://taconiteworkers.umn.edu/news/documents/Taconite_FinalReport_120114.pdf). NRRI’s “Environmental Study of Airborne Particulate Matter” comprises a multi-faceted characterization of size-fractionated airborne particulate matter (PM) from MIR community “rooftop” locations, background sites, and all taconite processing facilities active between 2008 and 2014. Characterization includes gravimetric determinations, chemical characterization, mineralogical characterization, and morphological characterization. This report specifically discusses the mineralogy and morphology of EMPs collected from the rooftops of five communities located within the MIR, three reference or background locations, and the six taconite processing plants. The samples were collected between 2008 and 2011.
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    Minnesota Taconite Workers Health Study: Environmental Study of Airborne Particulate Matter in Mesabi Iron Range Communities and Taconite Processing Plants - Development of Standard Operating Procedures for Particulate Collection and Gravimetric Analysis
    (University of Minnesota Duluth, 2019-12) Monson Geerts, Stephen D; Hudak, George J; Marple, Virgil; Lundgren, Dale; Olson, Bernard; Zanko, Lawrence M; Bandli, Bryan; Brecke, Devon M
    The Minnesota Taconite Workers Health Study (MTWHS) was initiated in 2008 and included a multicomponent study to further understand taconite worker health issues on the Mesabi Iron Range (MIR) in northeastern Minnesota. Approximately $4.9 million funding was provided by the Minnesota Legislature to conduct five separate studies related to this initiative, including:  An Occupational Exposure Assessment, conducted by the University of Minnesota School of Public Health (SPH);  A Mortality (Cause of Death) study, conducted by the University of Minnesota SPH;  Incidence studies, conducted by the University of Minnesota SPH;  A Respiratory Survey of Taconite Workers and Spouses, conducted by the University of Minnesota SPH; and  An Environmental Study of Airborne Particulate Matter, conducted by the Natural Resources Research Institute (NRRI) at the University of Minnesota Duluth (UMD). NRRI’s “Environmental Study of Airborne Particulate Matter” comprises a multi-faceted characterization of size-fractionated airborne particulate matter (PM) from MIR community “rooftop” locations, background sites, and all taconite processing facilities active between 2008 and 2014. Characterization includes gravimetric determinations, chemical characterization, mineralogical characterization, and morphological characterization. This report discusses the standard operating procedures for particle collection and gravimetric analysis. The methodology and practices that have been developed and performed have been completed in conjunction with NRRI’s Science Advisory Board and in collaboration with aerosol scientists at the University of Minnesota Department of Mechanical Engineering and University of Florida-Gainesville. As well, this report outlines the development of the sampling methodology and the history of in-house experiments conducted throughout the project to strengthen the sampling design that ultimately resulted in the development of the standard operating procedures adopted by, and practiced in, this portion of the study. Definitions for specific terms used in this document are consistent with terminology described in Appendix G.
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    Minnesota Taconite Workers Health Study: Environmental Study of Airborne Particulate Matter in Mesabi Iron Range Communities and Taconite Processing Plants - Elemental Chemistry of Particulate Matter
    (University of Minnesota Duluth, 2019-12) Monson Geerts, Stephen D; Hudak, George J; Marple, Virgil; Lundgren, Dale; Gordee, Sarah M; Olson, Bernard; Zanko, Lawrence M
    The Minnesota Taconite Workers Health Study (MTWHS) was initiated in 2008 and included a multicomponent study to further understand taconite worker health issues on the Mesabi Iron Range (MIR) in northeastern Minnesota. Approximately $4.9 million funding was provided by the Minnesota Legislature to conduct five separate studies related to this initiative, including: ▪ An Occupational Exposure Assessment, conducted by the University of Minnesota School of Public Health (SPH); ▪ A Mortality (Cause of Death) study, conducted by the University of Minnesota SPH; ▪ Incidence studies, conducted by the University of Minnesota SPH; ▪ A Respiratory Survey of Taconite Workers and Spouses, conducted by the University of Minnesota SPH; and ▪ An Environmental Study of Airborne Particulate Matter, conducted by the Natural Resources Research Institute (NRRI) at the University of Minnesota Duluth (UMD). NRRI’s “Environmental Study of Airborne Particulate Matter” comprises a multi-faceted characterization of size-fractionated airborne particulate matter (PM) from MIR community “rooftop” locations, background sites, and all taconite processing facilities active between 2008 and 2014. Characterization includes gravimetric determinations, chemical characterization, mineralogical characterization, and morphological characterization. This report specifically discusses the elemental chemistry of particulate matter (PM) collected from the rooftops of five communities located within the Mesabi Iron Range (MIR), three reference or background locations, and the six taconite processing plants while they were active (operating) and inactive (temporarily, but completely, shut down). The samples were collected between 2008 and 2011.
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    Minnesota Taconite Workers Health Study: Environmental Study of Airborne Particulate Matter in Mesabi Iron Range Communities and Taconite Processing Plants - Mesabi Iron Range Community Particulate Matter Collection and Gravimetric Analysis
    (University of Minnesota Duluth, 2019-12) Monson Geerts, Stephen D; Hudak, George J; Marple, Virgil; Lundgren, Dale; Zanko, Lawrence M; Olson, Bernard
    The Minnesota Taconite Workers Health Study (MTWHS) was initiated in 2008 and included a multicomponent study to further understand taconite worker health issues on the Mesabi Iron Range (MIR) in northeastern Minnesota. Approximately $4.9 million funding was provided by the Minnesota Legislature to conduct five separate studies related to this initiative, including:  An Occupational Exposure Assessment, conducted by the University of Minnesota School of Public Health (SPH);  A Mortality (Cause of Death) study, conducted by the University of Minnesota SPH;  Incidence studies, conducted by the University of Minnesota SPH;  A Respiratory Survey of Taconite Workers and Spouses, conducted by the University of Minnesota SPH; and  An Environmental Study of Airborne Particulate Matter, conducted by the Natural Resources Research Institute (NRRI) at the University of Minnesota Duluth (UMD). NRRI’s “Environmental Study of Airborne Particulate Matter” comprises a multi-faceted characterization of size-fractionated airborne particulate matter (PM) from MIR community “rooftop” locations, background sites, and all taconite processing facilities active between 2008 and 2014. Characterization includes gravimetric determinations, chemical characterization, mineralogical characterization, and morphological characterization. This report specifically discusses the methods and gravimetric results of multiple aerosol PM sample collections from five communities located within the MIR, as well as three background locations. The samples were collected between 2008 and 2011.