Albert H Hofstra (Former Employee)
Science and Products
Filter Total Items: 83
Analyzing legacy U.S. Geological Survey geochemical databases using GIS: applications for a national mineral resource assessment Analyzing legacy U.S. Geological Survey geochemical databases using GIS: applications for a national mineral resource assessment
This report emphasizes geographic information system analysis and the display of data stored in the legacy U.S. Geological Survey National Geochemical Database for use in mineral resource investigations. Geochemical analyses of soils, stream sediments, and rocks that are archived in the National Geochemical Database provide an extensive data source for investigating geochemical anomalies...
Authors
Douglas B. Yager, Albert H. Hofstra, Matthew Granitto
Integration of new geologic mapping and satellite-derived quartz mapping yields insights into the structure of the Roberts Mountains allochthon applicable to assessments for concealed Carlin-type gold deposits Integration of new geologic mapping and satellite-derived quartz mapping yields insights into the structure of the Roberts Mountains allochthon applicable to assessments for concealed Carlin-type gold deposits
Geologic mapping and remote sensing across north-central Nevada enable recognition of a thick sheet of Middle and Upper Ordovician Valmy Formation quartzite that structurally overlies folded and faulted Ordovician through Devonian stratigraphic units of the Roberts Mountains allochthon. In the northern Independence Mountains and nearby Double Mountain area, the Valmy Formation is in...
Authors
Christopher S. Holm-Denoma, Albert H. Hofstra, Barnaby W. Rockwell, Paula J. Noble
Shipboard magnetic field "noise" reveals shallow heavy mineral sediment concentrations in Chesapeake Bay Shipboard magnetic field "noise" reveals shallow heavy mineral sediment concentrations in Chesapeake Bay
Shipboard magnetic field data collected over Chesapeake Bay exhibit low-amplitude, short-wavelength anomalies that most likely indicate shallow concentrations of heavy mineral sediments. Piston core layers and black sand beach samples exhibit enhanced magnetic susceptibilities and carry remanent magnetization, with mineralogical analyses indicating ilmenite and trace magnetite and/or...
Authors
Anjana K. Shah, Peter R. Vogt, Joseph G. Rosenbaum, Wayne L. Newell, Thomas M. Cronin, Debra A. Willard, Rick A. Hagen, John Brozena, Albert Hofstra
Mapping argillic and advanced argillic alteration in volcanic rocks, quartzites, and quartz arenites in the western Richfield 1° x 2 ° quadrangle, southwestern Utah, using ASTER satellite data Mapping argillic and advanced argillic alteration in volcanic rocks, quartzites, and quartz arenites in the western Richfield 1° x 2 ° quadrangle, southwestern Utah, using ASTER satellite data
The Richfield quadrangle in southwestern Utah is known to contain a variety of porphyry Mo, skarn, polymetallic replacement and vein, alunite, and kaolin resources associated with 27-32 Ma calc-alkaline or 12-23 Ma bimodal volcano-plutonic centers in Neoproterozoic to Mesozoic carbonate and siliciclastic rocks. Four scenes of visible to shortwave-infrared image data acquired by the...
Authors
Barnaby W. Rockwell, Albert H. Hofstra
Occurrence model for volcanogenic beryllium deposits Occurrence model for volcanogenic beryllium deposits
Current global and domestic mineral resources of beryllium (Be) for industrial uses are dominated by ores produced from deposits of the volcanogenic Be type. Beryllium deposits of this type can form where hydrothermal fluids interact with fluorine and lithophile-element (uranium, thorium, rubidium, lithium, beryllium, cesium, tantalum, rare earth elements, and tin) enriched volcanic...
Authors
Nora K. Foley, Albert H. Hofstra, David A. Lindsey, Robert R. Seal, Brian W. Jaskula, Nadine M. Piatak
Ore genesis constraints on the Idaho Cobalt Belt from fluid inclusion gas, noble gas isotope, and ion ratio analyses Ore genesis constraints on the Idaho Cobalt Belt from fluid inclusion gas, noble gas isotope, and ion ratio analyses
The Idaho cobalt belt is a 60-km-long alignment of deposits composed of cobaltite, Co pyrite, chalcopyrite, and gold with anomalous Nb, Y, Be, and rare-earth elements (REEs) in a quartz-biotite-tourmaline gangue hosted in Mesoproterozoic metasedimentary rocks of the Lemhi Group. It is the largest cobalt resource in the United States with historic production from the Blackbird Mine. All...
Authors
Albert H. Hofstra, Gary P. Landis
Science and Products
Filter Total Items: 83
Analyzing legacy U.S. Geological Survey geochemical databases using GIS: applications for a national mineral resource assessment Analyzing legacy U.S. Geological Survey geochemical databases using GIS: applications for a national mineral resource assessment
This report emphasizes geographic information system analysis and the display of data stored in the legacy U.S. Geological Survey National Geochemical Database for use in mineral resource investigations. Geochemical analyses of soils, stream sediments, and rocks that are archived in the National Geochemical Database provide an extensive data source for investigating geochemical anomalies...
Authors
Douglas B. Yager, Albert H. Hofstra, Matthew Granitto
Integration of new geologic mapping and satellite-derived quartz mapping yields insights into the structure of the Roberts Mountains allochthon applicable to assessments for concealed Carlin-type gold deposits Integration of new geologic mapping and satellite-derived quartz mapping yields insights into the structure of the Roberts Mountains allochthon applicable to assessments for concealed Carlin-type gold deposits
Geologic mapping and remote sensing across north-central Nevada enable recognition of a thick sheet of Middle and Upper Ordovician Valmy Formation quartzite that structurally overlies folded and faulted Ordovician through Devonian stratigraphic units of the Roberts Mountains allochthon. In the northern Independence Mountains and nearby Double Mountain area, the Valmy Formation is in...
Authors
Christopher S. Holm-Denoma, Albert H. Hofstra, Barnaby W. Rockwell, Paula J. Noble
Shipboard magnetic field "noise" reveals shallow heavy mineral sediment concentrations in Chesapeake Bay Shipboard magnetic field "noise" reveals shallow heavy mineral sediment concentrations in Chesapeake Bay
Shipboard magnetic field data collected over Chesapeake Bay exhibit low-amplitude, short-wavelength anomalies that most likely indicate shallow concentrations of heavy mineral sediments. Piston core layers and black sand beach samples exhibit enhanced magnetic susceptibilities and carry remanent magnetization, with mineralogical analyses indicating ilmenite and trace magnetite and/or...
Authors
Anjana K. Shah, Peter R. Vogt, Joseph G. Rosenbaum, Wayne L. Newell, Thomas M. Cronin, Debra A. Willard, Rick A. Hagen, John Brozena, Albert Hofstra
Mapping argillic and advanced argillic alteration in volcanic rocks, quartzites, and quartz arenites in the western Richfield 1° x 2 ° quadrangle, southwestern Utah, using ASTER satellite data Mapping argillic and advanced argillic alteration in volcanic rocks, quartzites, and quartz arenites in the western Richfield 1° x 2 ° quadrangle, southwestern Utah, using ASTER satellite data
The Richfield quadrangle in southwestern Utah is known to contain a variety of porphyry Mo, skarn, polymetallic replacement and vein, alunite, and kaolin resources associated with 27-32 Ma calc-alkaline or 12-23 Ma bimodal volcano-plutonic centers in Neoproterozoic to Mesozoic carbonate and siliciclastic rocks. Four scenes of visible to shortwave-infrared image data acquired by the...
Authors
Barnaby W. Rockwell, Albert H. Hofstra
Occurrence model for volcanogenic beryllium deposits Occurrence model for volcanogenic beryllium deposits
Current global and domestic mineral resources of beryllium (Be) for industrial uses are dominated by ores produced from deposits of the volcanogenic Be type. Beryllium deposits of this type can form where hydrothermal fluids interact with fluorine and lithophile-element (uranium, thorium, rubidium, lithium, beryllium, cesium, tantalum, rare earth elements, and tin) enriched volcanic...
Authors
Nora K. Foley, Albert H. Hofstra, David A. Lindsey, Robert R. Seal, Brian W. Jaskula, Nadine M. Piatak
Ore genesis constraints on the Idaho Cobalt Belt from fluid inclusion gas, noble gas isotope, and ion ratio analyses Ore genesis constraints on the Idaho Cobalt Belt from fluid inclusion gas, noble gas isotope, and ion ratio analyses
The Idaho cobalt belt is a 60-km-long alignment of deposits composed of cobaltite, Co pyrite, chalcopyrite, and gold with anomalous Nb, Y, Be, and rare-earth elements (REEs) in a quartz-biotite-tourmaline gangue hosted in Mesoproterozoic metasedimentary rocks of the Lemhi Group. It is the largest cobalt resource in the United States with historic production from the Blackbird Mine. All...
Authors
Albert H. Hofstra, Gary P. Landis