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Results from our Program’s research and minerals information activities are published in USGS publications series as well as in outside journals.  To follow Minerals Information Periodicals, subscribe to the Mineral Periodicals RSS feed.

Filter Total Items: 2154

Towards a holistic sulfate-water-O2 triple oxygen isotope systematics

Triple oxygen isotope (∆17O with δ18O) signals of H2O and O2 found in sulfate of oxidative weathering origin offer promising constraints on modern and ancient weathering, hydrology, atmospheric gas concentrations, and bioproductivity. However, interpretations of the sulfate-water-O2 system rely on assuming fixed oxygen-isotope fractionations between sulfate and water, which, contrastingly, are sho

Assessment of undiscovered copper resources of the world, 2015

The U.S. Geological Survey completed the first-ever global assessment of undiscovered copper resources for the two most significant sources of global copper supply: porphyry copper deposits and sediment-hosted stratabound copper deposits. The geology-based study identified 236 areas for undiscovered copper in 11 regions of the world. Estimated amounts of undiscovered copper resources are reported

Mapping critical minerals from the sky

Critical mineral resources titanium, zirconium, and rare earth elements occur in placer deposits over vast parts of the U.S. Atlantic Coastal Plain. Key questions regarding provenance, pathways of minerals to deposit sites, and relations to geologic features remain unexplained. As part of a national effort to collect data over regions prospective for critical minerals, the first public high-resolu

Geochemistry and mineralogy of metallurgical slag

Slag is a waste product from the pyrometallurgical processing of natural ores or the recycling of man-made materials. This chapter provides an overview of the geochemical and mineralogical characteristics of different types of slag. A review of the analytical methods used to determine these characteristics is also provided. Ferrous slags include blast furnace, steelmaking, and ferroalloy slags; th

Reconnaissance study of the major and trace element content of bauxite deposits in the Arkansas bauxite region, Saline and Pulaski Counties, central Arkansas

The Arkansas bauxite district, which comprises about 275 square miles (710 square kilometers) of central Arkansas, produced an order of magnitude more bauxite and alumina than the other bauxite districts in the United States combined. Bauxite was mined in the region continuously from 1898 to 1982. These bauxites are laterite deposits, formed from intensive in-place weathering of the exposed surfac

Chemical and structural degradation of CH3NH3PbI3 propagate from PEDOT:PSS interface in the presence of humidity

Understanding interfacial reactions that occur between the active layer and charge-transport layers can extend the stability of perovskite solar cells. In this study, the exposure of methylammonium lead iodide (CH3NH3PbI3) thin films prepared on poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS)-coated glass to 70% relative humidity (R.H.) leads to a perovskite crystal structure c

Economic geology and environmental characteristics of antimony deposits

Antimony is commonly listed as a critical mineral, particularly in the United States and European Union [1]. Its criticality, or supply risk, is derived from a combination of economic vulnerability, disruption potential of supply, and trade exposure [2].Disruption potential relates a country’s ability and willingness to supply a commodity. Commodities for which supply is concentrated in the fewest

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

Dating fault damage along the eastern Denali fault zone with hematite (U-Th)/He thermochronometry

Unraveling complex slip histories in fault damage zones to understand relations among deformation, hydrothermal alteration, and surface uplift remains a challenge. The dextral eastern Denali fault zone (EDFZ; southwest Yukon, Canada) bounds the Kluane Ranges and hosts a variety of fault-related rocks, including hematite fault surfaces, which have been exhumed through the brittle regime over a prot

Petrology and geochronology of 1.48 to 1.45 Ga igneous rocks in the St. Francois Mountains terrane, southeast Missouri

The igneous geology of the St. Francois Mountains terrane in southeast Missouri is dominated by the products of 1.48 to 1.45 billion year old volcanic and plutonic magmatism but also includes volumetrically minor, compositionally bimodal contributions added during plutonism between 1.34 and 1.27 billion years ago. The 1.48 to 1.45 billion year old igneous rocks in the St. Francois Mountains terran

The role of hydrates, competing chemical constituents, and surface composition on CLNO2 formation

Atomic chlorine (Cl•) affects air quality and atmospheric oxidizing capacity. Nitryl chloride (ClNO2) – a common Cl• source–forms when chloride-containing aerosols react with dinitrogen pentoxide (N2O5). A recent study showed that saline lakebed (playa) dust is an inland source of particulate chloride (Cl–) that generates high ClNO2. However, the underlying physiochemical factors responsible for o

Tectonic and magmatic controls on the metallogenesis of porphyry deposits in Alaska

Porphyry Cu and Mo deposits and occurrences are found throughout Alaska; they formed episodically during repeated subduction and arc-continent collisions spanning the Silurian to Quaternary. Porphyry systems occur in continental-margin and island arcs, which are broadly grouped into pre-accretionary or post-accretionary arcs. Pre-Mesozoic occurrences formed in continental or island arcs prior to a