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The mineral pyrrhotite, which is an unstable sulfide mineral, was present in crushed stone aggregate used in concrete foundations of homes in Connecticut and Massachusetts, many of those foundations are failing as the mineral weathers. Because of the substantial costs of lifting homes and replacing their foundations, in 2019 the U.S. Congress directed the U.S. Geological Survey’s (USGS) Mineral Resources Program to help assess the national risk of pyrrhotite in aggregate. The data presented here help form a map that shows where pyrrhotite may occur across the conterminous United States, which can help inform risk assessments. Pyrrhotite occurs in some mineral deposits, and it also forms from pyrite during metamorphism,...
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This DGGS Raw Data File presents 40Ar/39Ar age dating results for selected igneous rocks encountered in the Styx River area of the western Alaska Range. Crystallization ages on biotite and hornblende from plutonic rocks range from about ~60 to ~63 Ma, while a sericite alteration age in plutonic rocks altered by a dike swarm also is around ~63 Ma. Sericite alteration associated with a copper-molybdenum porphyry ranges from ~10 to ~11 Ma. Analyses were performed by the University of Alaska Fairbanks Geochronology Laboratory, and results were reported by Paul Layer and Jeff Benowitz. This data release includes the following products: a summary of sample collection methods, the laboratory report, analytical data tables...


    map background search result map search result map 40Ar/39Ar data, Styx River map area, Lime Hills C-1 Quadrangle, Alaska Data to accompany U.S. Geological Survey Fact Sheet 2020-3017: Pyrrhotite distribution in the conterminous United States 40Ar/39Ar data, Styx River map area, Lime Hills C-1 Quadrangle, Alaska Data to accompany U.S. Geological Survey Fact Sheet 2020-3017: Pyrrhotite distribution in the conterminous United States