Images

Ernie Valdez, USGS Fort Collins Science Center, examines a bat caught over the mine detention pond.

A field assistant pans for monazite and rare earth minerals in Wolf Creek, which cuts through the Melozitna granite. This area is part of the Bureau of Land Management's Central Yukon Planning Area, where USGS did a critical mineral assessment in 2015.

The Concord heavy-mineral-sands mine of Iluka Resources in south-central Virginia.

Mylonitic breccia in alluvium of Little Deer Creek, downstream from a moderately west-dipping contact between biotitic quartzite of the Gunsight Formation, which is structurally overlain by garnet-chloritoid-bearing banded siltite of the banded siltite unit of the Apple Creek Formation.

Small-scale syncline in siltite of banded siltite unit of Apple Creek Formation, within a zone of tight, north-plunging chevron folds, exposed on the south-facing slope above the upper part of Little Deer Creek, east of the Blackbird cobalt-copper mine area, in east-central Idaho.

Outcrop of biotitic meta-sandstone in the lower part of the Gunsight Formation, cut by white quartz veins with alteration envelopes of coarsely crystalline black biotite and minor muscovite. USGS intern, Shane Kostka prepares to collect representative samples from this outcrop.

Limonite-stained outcrop of the banded siltite unit of the Apple Creek Formation, near Blackbird Creek, south of the Blackbird cobalt-copper mine area, in the Salmon River Mountains of east-central Idaho.

Outcrop of the banded siltite unit of the Apple Creek Formation of the Lemhi Group, in the Lemhi sub-basin of the Mesoproterozoic Belt Basin. This exposure is along the Deep Creek road, southeast of the Blackbird cobalt-copper mine area, in the Salmon River Mountains of east-central Idaho.

A thick lens of biotite-rich rock, interlayered with thick beds of cross-bedded meta-sandstone + scapolite of the Gunsight Formation of the Lemhi Group in the Lemhi sub-basin of the Mesoproterozoic Belt Basin. The biotite-rich rock is exposed in a prospect pit above the Sweet Repose mine adit.

Blocks of biotitic meta-sandstone from the lower part of the Gunsight Formation, and drill core from the underlying banded siltite unit of the Apple Creek Formation, lying on the dump of the lower workings of the Copper Queen mine, southeast of the Blackbird cobalt-copper mine area.

Outcrop of the banded siltite unit of the Apple Creek Formation, east of the Slippery Gulch fault, and south of the Blackbird cobalt-copper mine area, in the Salmon River Mountains of east-central Idaho.

Quartz vein in biotite-rich rock in the Gunsight Formation of the Mesoproterozoic Lemhi Group. Bluish green copper-bearing minerals coat the quartz vein. Pale pinkish cobalt bloom and white caliche coat adjacent biotite-rich wallrock.

Cross-bedded sandstone of the Gunsight Formation of the Mesoproterozoic Lemhi Group. These beds are interpreted as products of alluvial sedimentation in a deltaic setting.

Figure 3. Secondary electron images of elongate amphibole bundles from the sink fractions of commercial expanded vermiculite ore.

Photo showing intense acid-sulfate hydrothermal alteration on Red Mountain No. 2, Silverton CO. View is looking to the west across Corkscrew Gulch. 

This setup is used for processing water-quality samples at Sowats Point on the Kaibab Plateau.

This view is from Sowats Point on the Kaibab Plateau, looking southwest towards Kanab Creek.

Supergene chrysocolla zone in the Ray porphyry copper mine.

Potash ore is mined at a depth of about 1500 m through a solution mining process. Examination of the world's largest potash producing basin was part of a global assessment of undiscovered.

Stratigraphic studies of Quaternary alluvium provides resource data to the U.S. aggregate industry.

Gordon Haxel (USGS, Flagstaff) explains the Jurassic geology of the Baboquivari Mountains, Arizona. Kitt Peak, Arizona, November 2009. Bob Powell (USGS, Tucson) holds the map.