Formed after a volcanic eruption when lava cools so fast that mineral crystals are unable to form, the rock appears as amorphous dark-colored glass known as obsidian. Notable qualities of obsidian ...

The Yellowstone Plateau Volcanic Field has some of the largest rhyolite lava flows on Earth. Have you ever wondered what these flows look like in their interior, or how the ...

Discover how an analysis of more than 700 objects reveals obsidian came into the Aztec capital from far and wide.

This was the start of the dream of KMT: The Krafla Magma Testbed, named for the volcanic system in Iceland. It’s a dream that ...

Then I came to Panarea and found one—with the whole world within it.” This scrawl, attributed to one “Mastro Ciccio, 1920”, ...

Of the eight active volcanoes on the USGC watch list, three are relatively easy to explore — Long Valley, Mt. Lassen, and ...

Yooperlites are a variety of sodalite-rich syenite found in the Upper Peninsula of Michigan.

Agates are formed when gas bubbles in lava leave a hole in the "vesicle" in the rock, according to the Michigan Department of Environment, Great Lakes, and Energy. Silica (silicon dioxide ...