Energy and Minerals

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Image shows a sample of lignite on a rock background
December 31, 2013

Lignite Coal

A sample of lignite, the lowest rank of coal. It is primarily mined for burning in steam-generation power plants. Read more about our coal research here: https://www.usgs.gov/centers/cersc/science/us-coal-resources-and-reserves-assessment

Image shows a sample of lignite on a rock background
December 31, 2013

Lignite Coal

A sample of lignite, the lowest rank of coal. It is primarily mined for burning in steam-generation power plants. Read more about our coal research here: https://www.usgs.gov/centers/cersc/science/us-coal-resources-and-reserves-assessment

Image shows a sample of lignite on a rock background
December 31, 2013

Lignite Coal

A sample of lignite, the lowest rank of coal. It is primarily mined for burning in steam-generation power plants. Read more about our coal research here: https://www.usgs.gov/centers/cersc/science/us-coal-resources-and-reserves-assessment

Image shows a sample of peat against a rock background
December 31, 2013

Peat

Peat is the precursor to coal. It's made up of decayed plant materials or other organic matter that, over time, can undergo heat and pressure to become lignite. Read more about our coal resources here: https://www.usgs.gov/centers/cersc/science/us-coal-

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Image shows a sample of peacock coal against a rock background
December 31, 2013

Peacock Coal

This sample is of peacock coal. Peacock coal is not a specific class of coal, but rather the name for an effect in which oxidizing materials in the coal create a dazzling array of colors on the surface of the coal. Usually it is short-lived, as the material fully oxidizes away shortly after exposed to air. Read more about our coal research here: 

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Image shows a sample of anthracite coal on a rock backdrop
December 31, 2013

Anthracite Coal

This is anthracite, the highest rank of coal. It is a hard, brittle, and black lustrous coal, often referred to as hard coal, containing a high percentage of fixed carbon and a low percentage of volatile matter. Anthracite is not as commonly mined as other ranks of coal. It played a significant role in Pennsylvania coal during the Industrial Revolution in the United

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Image shows a sample of bituminous coal on a rock backdrop
December 31, 2013

Bituminous Coal

This sample is of bituminous coal, a middle rank coal (between subbituminous and anthracite) formed by additional pressure and heat on lignite. Usually has a high Btu value and may be referred to as "soft coal." Read more about USGS coal research here: 

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Image shows a sample of anthracite coal on a rock backdrop
December 31, 2013

Anthracite Coal

This is anthracite, the highest rank of coal. It is a hard, brittle, and black lustrous coal, often referred to as hard coal, containing a high percentage of fixed carbon and a low percentage of volatile matter. Anthracite is not as commonly mined as other ranks of coal. It played a significant role in Pennsylvania coal during the Industrial Revolution in the United

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Image shows a sample of clinker on a rock background
December 31, 2013

Clinker Coal

Clinker coal is the result of a seam of coal catching fire and burning so hot that it baked surrounding rock layers into brick-like formations. Some of the most famous clinker formations in the United States can be seen at the Theodore Roosevel National Park in North Dakota. Read more about our

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Sandstone block shown here contains a large fossil palm leaf.
December 4, 2013

Sandstone Block with Large Fossil Palm Leaf

Most fossils occur in sedimentary rocks including shale, limestone and sandstone. The sandstone block shown here contains a large fossil palm leaf, found at the Coryell Coal mines in Colorado. “Fossil plants and animals became important tools for establishing the geologic age of rocks and correlating them from one region to another.” This photo was taken

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Image shows a pyramidal rock formation with grass around it and three USGS scientists standing near the base
September 16, 2013

Surprise Creek, Western North Slope of Alaska

Geologists measuring petroleum source rocks in Triassic rocks along Surprise Creek in southern part of Western North Slope.

Image shows exposed rock formations with grass coverings
September 16, 2013

Surprise Creek, Western North Slope of Alaska

Geologist describes petroleum source rocks in Triassic and Jurassic rocks along Surprise Creek in southern part of Western North Slope.