Eastern Mineral and Environmental Resources Science Center

Cross-polarized light photomicrograph of minerals in drill core samples from the Local Boy deposit, Duluth Complex, Minnesota. The number in the upper right hand corner is the drill core number.

A sample of azurite, the blue mineral, and malachite, the green mineral. Both azurite and malachite are copper minerals that were once used as pigments but are now mostly valued as collectors minerals. They do serve as good indicators of copper deposits that can be developed. Read more information about copper here.

Cross-polarized light photomicrograph of minerals in drill core samples from the Mesaba copper-nickel deposit, Duluth Complex, Minnesota. The number in the upper right hand corner is the drill core number.

This sample is clinozoisite, a calcium aluminum silicate mineral. It is mostly prized as a collectors mineral rather than a source of its industrial mineral commodities.

Sample provided by Carlin Green, USGS. Sample originated from Hachupa, Pakistan, and is 6.0cm in size.

Scanning Electron Microscope backscatter image of legacy steelmaking slag from the Calumet region, Chicago, Illinois, showing silicate minerals, some of which may have acid-neutralizing potential.

Elbaite is one of the best-known members of the tourmaline mineral family, particularly for its high-quality gemstones. Read more about the tourmaline mineral family here. 

Sample provided by Carlin Green, USGS. Sample originated from Himalaya Mine, California, and is 4

Scientists sampling water and measuring streamflow in Keeley Creek, a stream in northern Minnesota that is in the vicinity of copper-nickel-platinum group element deposits. 

Epidote is a silicate mineral used mostly as a semiprecious gemstone.

Sample provided by Carlin Green, USGS. Sample originated from Prince of Wales Island, Alaska, and is 6.0cm in size.

USGS scientists sampling​ the​ Ironwood Iron-Formation, Gogebic ​I​ron ​R​ange in northern Wisconsin.

Pyrrhotite is an iron sulfide mineral related to iron pyrite, which is one of the minerals known as Fool's Gold. Pyrrhotite, although not one of the Fool's Gold minerals, is sometimes called magnetic pyrite as it is weakly magnetic. It is most valued as a collectors mineral.

Sample provided by Carlin Green, USGS. Sample originated from Eagle Mine, Michigan, and is 4

Scientists standing on an outcrop of the Ironwood Iron-Formation, Gogebic Iron Range in northern Wisconsin.