Images

Intensely altered propylitic rocks (red and yellow) in the Red Mountain mining district, overprinting the regional, propylitically altered igneous rocks (grayish-green), peaks at top of image. View to west.

Sample of eudialyte (pink) within layered vein consisting of quartz, albite, and sodic amphibole, Dora Bay, Alaska. Size of sample is 11 by 9 cm. Sample of coarse-grained, tabular bastnäsite within matrix of ferruginous dolomite, Birthday Claim, Mountain Pass, California. Photographs by Philip Verplanck, U.S. Geological Survey. SIR 2010-5070-J

Geologist doing field work in Alaska

Aerial view over Weka Dur, Afghanistan’s largest known gold deposit, Badakhshan Province.

Light-colored rocks in the foreground overlay a pluton, formed as a plume of magma rose, cooled and deposited minerals in the earth’s crust. Sedimentary rocks dip away from the intrusion.

Aerial view looking into the center of the dome-shaped pluton.

A low-level helicopter towing a large wire-loop contraption hanging from a cable is flying straight across an open field in Nebraska on a clear day.

Aerial view near Herat. Dark red iron stains hint that other minerals might be found.

Helicopter towing a large, wire-loop contraption hanging from a cable is turning in air on a relatively clear day in Nebraska.

USGS scientist Art Bookstrom uses a hand-lens to search for sulfide minerals in oxidized copper-cobalt-bearing siltite of the banded siltite unit of the Apple Creek Formation, exposed in the Blacktail pit of the Blackbird cobalt-copper mine, Salmon River Mountains, east-central Idaho.

USGS scientist John Slack holds his hammer to a biotitic mafic dike, intruded into twice-folded banded siltite, exposed in the Hawkeye adit of the Blackbird cobalt-copper mine, in the Salmon River Mountains of east-central Idaho. Biotite is a type of mica, and mafic refers to a high magnesium and iron content.

USGS scientist Art Bookstrom looks at puzzling sedimentary structures in metasedimentary rocks of the Apple Creek Formation, near the Jackass prospect, near Iron Creek, in the southeastern part of the Idaho cobalt belt, in east-central Idaho.

USGS scientist Art Bookstrom looks at greenish copper stain and pale pink cobalt bloom on limonite-stained meta-siltite and meta-argillite at the No Name prospect, near Iron Creek, in the southeastern part of the Idaho cobalt belt, in east-central Idaho.

USGS scientist Art Bookstrom hammers on limonite-stained breccia, cutting banded siltite of the Apple Creek Formation, exposed near the Uncle Sam portal of the Blackbird cobalt-copper mine, in the Salmon River Mountains of east-central Idaho.

USGS scientist Art Bookstrom maps and samples a gossan, developed on tightly folded, mineralized, metamorphosed, and weathered banded siltite, exposed on the southwest rim of the Blacktail pit of the Blackbird cobalt-copper mine, in the Salmon River Mountains of east-central Idaho. The gossan is overlain by unconsolidated colluvial debris.

USGS scientist Steve Box takes an oriented sample of folded, crenulated, and metamorphosed banded siltite, exposed in the Blacktail pit of the Blackbird cobalt-copper mine, in the Salmon River Mountains of east-central Idaho.

USGS scientist Tom Frost measures the distance across the transition from garnet-bearing rocks, upslope from the end of the tape, to garnet-free rocks below it, as exposed on the northeast wall of the Blacktail pit of the Blackbird cobalt-copper mine, in the Salmon River Mountains of east-central Idaho.

USGS scientist Tom Frost stands on the northeast rim of the Blacktail pit of the Blackbird cobalt-copper mine, in the Salmon River Mountains of east-central Idaho.

USGS scientist Art Bookstrom photographs copper-stained banded siltite, exposed in the Blacktail pit of the Blackbird cobalt-copper mine, Salmon River Mountains, east-central Idaho.

Residents and visitors should not be alarmed to witness a low-flying helicopter over southeastern Missouri starting in mid to late February, 2014.

Specimen of stibnite, an ore mineral of antimony. Antimony compounds help to prevent skin burns, increase battery life, and refine the glass used in cell-phone screens.