Skip to main content
U.S. flag

An official website of the United States government

Albert H Hofstra

Al Hofstra is a Research Geologist with the Geology, Geophysics, and Geochemistry Science Center.

Science and Products

link
Li brine and clay conceptual model

Lithium from Source to Sink: Genesis and Evolution of Li Brines and Clays

The purpose of this project is to trace the lithium (Li) geochemical cycle in the Great Basin, with an emphasis on the pathways that lead to the development of lithium clay and brine resources.
By
Mineral Resources Program, Geology, Geophysics, and Geochemistry Science Center, Geology, Minerals, Energy, and Geophysics Science Center
link

Lithium from Source to Sink: Genesis and Evolution of Li Brines and Clays

The purpose of this project is to trace the lithium (Li) geochemical cycle in the Great Basin, with an emphasis on the pathways that lead to the development of lithium clay and brine resources.
Learn More
link
critical mineral distribution map

Systems Approach to Critical Minerals Inventory, Research, and Assessment

This project supports the Earth Mapping Resources Initiative (EarthMRI) by developing a mineral systems approach for defining focus areas. This project is investigating domestic sources of critical minerals in three sequential stages: inventory, research, and assessment. 1) Inventory the abundance of critical minerals in ore, minerals, and processed materials from major deposits in each system...
By
Mineral Resources Program, Geology, Geophysics, and Geochemistry Science Center, Geology, Minerals, Energy, and Geophysics Science Center, Earth Mapping Resources Initiative (Earth MRI)
link

Systems Approach to Critical Minerals Inventory, Research, and Assessment

This project supports the Earth Mapping Resources Initiative (EarthMRI) by developing a mineral systems approach for defining focus areas. This project is investigating domestic sources of critical minerals in three sequential stages: inventory, research, and assessment. 1) Inventory the abundance of critical minerals in ore, minerals, and processed materials from major deposits in each system...
Learn More

National Geochemical Database on Ore Deposits: Legacy data

There is a growing demand for commodities (elements, compounds, minerals) used in today's advanced technologies. Critical minerals are usually found in ore deposits that are deemed vital to economic and national security. The National Geochemical Database on Ore Deposits: Legacy data (NGDOD) contains chemistry and geologic information for nearly 30,000 historic ore and ore-related rock samples fro
By
Geology, Geophysics, and Geochemistry Science Center

Melt inclusion and mineral geochemical analyses supporting the evaluation of petrogenesis, degassing, and metallogenic potential of mid-Cenozoic rhyolite magmas in northern Nevada, USA

This data release presents geochemical analyses of silicate melt inclusions, host quartz phenocrysts, and biotite phenocrysts in samples collected by the U.S. Geological Survey (USGS) from mid-Cenozoic rhyolitic rocks from northern Nevada. Igneous intrusions and volcanic rocks in this study encompass nineteen rhyolitic samples from five magmatic centers across northeastern Nevada. Rhyolites were e
By
Geology, Geophysics, and Geochemistry Science Center

Global Geochemical Database for Critical Minerals in Archived Mine Samples

The Critical Minerals in Archived Mine Samples Database (CMDB) contains chemistry and geologic information for historic ore and ore-related rock samples from mineral deposits in the United States. In addition, the database contains samples from archetypal deposits from 27 other countries in North America, South America, Asia, Africa and Europe. Samples were obtained from archived ore collections u
By
Mineral Resources Program, Geology, Geophysics, and Geochemistry Science Center

GIS and Data Tables for Focus Areas for Potential Domestic Nonfuel Sources of Rare Earth Elements

In response to Executive Order 13817 of December 20, 2017, the U.S. Geological Survey (USGS) coordinated with the Bureau of Land Management (BLM) to identify 35 nonfuel minerals or mineral materials considered critical to the economic and national security of the United States (U.S.). Acquiring information on possible domestic sources of these critical minerals is the basis of the USGS Earth Mappi
By
Mineral Resources Program, Geology, Geophysics, and Geochemistry Science Center, Earth Mapping Resources Initiative (Earth MRI)

Locatable Mineral Assessment Tracts for the U.S. Geological Survey Sagebrush Mineral Resource Assessment Project

The polygon (vector) feature class represents locatable mineral resource assessment tracts (tracts of land) associated with the Department of the Interior (DOI) Sagebrush Focal Areas in Montana, Wyoming and Utah, central Idaho, and the Oregon-Nevada-Idaho border area. The mineral resources tracts are geographic areas that were assessed by the U.S. Geological Survey (USGS) and were determined to be
By
Mineral Resources Program, Geology, Geophysics, and Geochemistry Science Center

Improved Automated Identification and Mapping of Iron Sulfate Minerals, Other Mineral Groups, and Vegetation using Landsat 8 Operational Land Imager Data, San Juan Mountains, Colorado, and Four Corners Region

Multispectral remote sensing data acquired by the Landsat 8 Operational Land Imager (OLI) sensor were analyzed using a new, automated technique to generate a map of exposed mineral and vegetation groups in the western San Juan Mountains, Colo., and the Four Corners Region of the United States. Band ratio results were combined into displayed mineral and vegetation groups using Boolean algebra. New
By
Mineral Resources Program, Geology, Geophysics, and Geochemistry Science Center
Filter Total Items: 74

40Ar/39Ar geochronology of magmatic-steam alunite from Alunite Ridge and Deer Trail Mountain, Marysvale Volcanic Field, Utah: Timing and duration of miocene hydrothermal activity associated with concealed intrusions

Porphyry and epithermal deposits are important sources of base and precious metals. Most actively mined deposits have been exhumed such that ore bodies are relatively close to the surface and are therefore locatable and economic to extract. Identifying and characterizing concealed deposits, particularly more deeply buried porphyry deposits, represents a far greater challenge for mineral exploratio
Authors
Cameron Mark Mercer, M. Cosca, Albert H. Hofstra, Wayne R. Premo, Robert O. Rye, Gary P. Landis
By
Mineral Resources Program, Geology, Geophysics, and Geochemistry Science Center

A case of Te-rich low-sulfidation epithermal Au-Ag deposits in a calc-alkaline magmatic arc, NE China

Tellurium-bearing low-sulfidation epithermal Au-Ag deposits are significant producers of gold, silver, and potentially strategic elements if mineral processing methods are optimized for recovery. Although these deposits are generally related to alkaline magmatism, our study documents an unusual occurrence of Te-rich low-sulfidation epithermal systems in the North Heilongjiang Belt in northeast Chi
Authors
Shen Gao, Albert H. Hofstra, K. Qin, H. Xue
By
Mineral Resources Program, Geology, Geophysics, and Geochemistry Science Center

Focus areas for data acquisition for potential domestic resources of 13 critical minerals in the conterminous United States and Puerto Rico — Antimony, barite, beryllium, chromium, fluorspar, hafnium, helium, magnesium, manganese, potash, uranium, vanadiu

The Earth Mapping Resources Initiative (Earth MRI) is conducted in phases to identify areas for acquiring new geologic framework data to identify potential domestic resources of the 35 mineral materials designated as critical minerals for the United States. This report describes the data sources and summary results for 13 critical minerals evaluated in the conterminous United States and Puerto Ric
Authors
Jane M. Hammarstrom, Connie L. Dicken, Laurel G. Woodruff, Allen K. Andersen, Sean T. Brennan, Warren C. Day, Benjamin J. Drenth, Nora K. Foley, Susan Hall, Albert H. Hofstra, Anne E. McCafferty, Anjana K. Shah, David A. Ponce
By
Energy and Minerals Mission Area, Mineral Resources Program, Central Energy Resources Science Center, Geology, Energy & Minerals Science Center, Geology, Geophysics, and Geochemistry Science Center, Geology, Minerals, Energy, and Geophysics Science Center, Earth Mapping Resources Initiative (Earth MRI)

Deposit classification scheme for the Critical Minerals Mapping Initiative Global Geochemical Database

A challenge for the global economy is to meet the growing demand for commodities used in today’s advanced technologies. Critical minerals are commodities (for example, elements, compounds, minerals) deemed vital to the economic and national security of individual countries that are vulnerable to supply disruption. The national geological agencies of Australia, Canada, and the United States recentl
Authors
Albert H. Hofstra, Vladimir Lisitsin, Louise Corriveau, Suzanne Paradis, Jan Peter, Kathleen Lauzière, Christopher Lawley, Michael Gadd, Jean-Luc Pilote, Ian Honsberger, Evgeniy Bastrakov, David Champion, Karol Czarnota, Michael Doublier, David Huston, Oliver Raymond, Simon VanDerWielen, Poul Emsbo, Matthew Granitto, Douglas C. Kreiner
By
Geology, Geophysics, and Geochemistry Science Center

Systems-deposits-commodities-critical minerals table for the earth mapping resources initiative

To define and prioritize focus areas across the United States with resource potential for 35 critical minerals in a few years’ time, the U.S Geological Survey Earth Mapping Resources Initiative (Earth MRI) required an efficient approach to streamline workflow. A mineral systems approach based on current understanding of how ore deposits that contain critical minerals form and relate to broader geo
Authors
Albert H. Hofstra, Douglas C. Kreiner
By
Geology, Geophysics, and Geochemistry Science Center, Earth Mapping Resources Initiative (Earth MRI)

Focus areas for data acquisition for potential domestic resources of 11 critical minerals in the conterminous United States, Hawaii, and Puerto Rico—Aluminum, cobalt, graphite, lithium, niobium, platinum-group elements, rare earth elements, tantalum, tin,

In response to a need for information on potential domestic sources of critical minerals, the Earth Mapping Resources Initiative (Earth MRI) was established to identify and prioritize areas for acquisition of new geologic mapping, geophysical data, and elevation data to improve our knowledge of the geologic framework of the United States. Phase 1 of Earth MRI concentrated on those geologic terrane
Authors
Jane M. Hammarstrom, Connie L. Dicken, Warren C. Day, Albert H. Hofstra, Benjamin J. Drenth, Anjana K. Shah, Anne E. McCafferty, Laurel G. Woodruff, Nora K. Foley, David A. Ponce, Thomas P. Frost, Lisa L. Stillings
By
Energy and Minerals Mission Area, Mineral Resources Program, Geology, Energy & Minerals Science Center, Geology, Geophysics, and Geochemistry Science Center, Geology, Minerals, Energy, and Geophysics Science Center, Earth Mapping Resources Initiative (Earth MRI)

Absence of magnetite microlites, geochemistry of magnetite veins and replacements in IOA deposits, SE Missouri, USA: Relations to intermediate intrusions

The paragenesis, textures, and chemical compositions of magnetite in two mafic to intermediate intrusions and four IOA deposits in SE Missouri were studied to discriminate between igneous and hydrothermal sources. In this study, we found that replacement magnetite with mineral inclusion-rich cores yields erroneously high Ti, Al, Si, Mg, and Mn contents as determined by EMP and LA-ICP-MS due to ru
Authors
Corey J. Meighan, Albert H. Hofstra, David Adams, Erin E. Marsh, Heather A. Lowers, Alan Koenig
By
Mineral Resources Program, Geology, Geophysics, and Geochemistry Science Center, Denver Microbeam Laboratory

Geochemistry of hematite veins in IOA-IOCG deposits of SE Missouri, USA: Relation to felsic magmatism and caldera lakes

The paragenesis, textures, and chemical compositions of secondary hematite in regional potassic altered rhyolites, four IOA deposits, the sedimentary iron deposit at Pilot Knob and the Boss IOCG deposit in SE Missouri were determined and compared to primary magnetite from the IOA and IOCG deposits. Magnetite is composed of elements characteristics of mafic to intermediate intrusions whereas hemati
Authors
Corey J. Meighan, Albert H. Hofstra, Erin E. Marsh, Heather A. Lowers, Alan Koenig
By
Mineral Resources Program, Geology, Geophysics, and Geochemistry Science Center, Denver Microbeam Laboratory

Crustal architecture beneath the southern Midcontinent (USA) and controls on Mesoproterozoic iron-oxide mineralization from 3D geophysical models

Several types of critical mineral-bearing ore deposits in the southern Midcontinent region of the U.S. are hosted in Mesoproterozoic igneous rocks largely concealed beneath Paleozoic cover. Discerning the architecture of igneous intrusions and volcanic centers in the crust is fundamental to understanding the geologic evolution of this vast region and its mineral resources. To advance the understan
Authors
Anne E. McCafferty, Jeffrey D. Phillips, Albert H. Hofstra, Warren C. Day
By
Mineral Resources Program, Geology, Geophysics, and Geochemistry Science Center

Tourmaline boron and strontium isotope systematics reveal magmatic fluid pulses and external fluid influx in a giant iron oxide-apatite (IOA) deposit

Tourmaline is a common boron-bearing mineral in hydrothermal system and has been widely used as a mineral probe to reconstruct geological processes because of its broad range in composition and resistance to metasomatic alteration. The origin of Kiruna-type iron oxide-apatite (IOA) deposits, commonly linked to andesitic subvolcanic or volcanic rocks, is highly controversial. Constraints on the evo
Authors
Zhi-kun Su, Xinfu Zhao, Li-ping Zeng, Kui-dong Zhao, Albert H. Hofstra
By
Geology, Geophysics, and Geochemistry Science Center

Noble gas data from Goldfield and Tonopah epithermal Au-Ag deposits, ancestral Cascades Arc, USA: Evidence for a primitive mantle volatile source

The He, Ne, and Ar isotopic composition of fluid inclusions in ore and gangue minerals were analyzed to determine the source of volatiles in the high-grade Goldfield and Tonopah epithermal Au-Ag deposits in southwestern Nevada, USA. Ar and Ne are mainly atmospheric, whereas He has only a minor atmospheric component. Corrected 3He/4He ratios (with atmospheric He removed) range widely from 0.05 to 3
Authors
Andrew H. Manning, Albert H. Hofstra
By
Mineral Resources Program, Geology, Geophysics, and Geochemistry Science Center, Subduction Zone Science

The Valmy thrust sheet: A regional structure formed during the protracted assembly of the Roberts Mountains allochthon, Nevada, USA

A synthesis of field, biostratigraphic, detrital zircon geochronologic, and remote sensing data across north-central Nevada, United States, defines a thick, regionally extensive sheet of Middle–Upper Ordovician Valmy Formation quartzite that structurally overlies deformed early Paleozoic units of the Roberts Mountains allochthon. Late Paleozoic regional unconformities that record tectonic disrupti
Authors
Christopher S. Holm-Denoma, Albert H. Hofstra, Barnaby W. Rockwell, Paula J. Noble
By
Mineral Resources Program, Geology, Geophysics, and Geochemistry Science Center

Science and Products