MICHAEL SZOENYI / SCIENCE PHOTO LIBRARY MICHAEL SZOENYI / SCIENCE PHOTO LIBRARY
Obsidian sample. Obsidian is a vitreous (glassy, non-crystalline) mineral that forms in extrusive rocks that are cooled rapidly, such as in volcanic eruptions. The reddish colour is where tuff from previous volcanic eruptions has been trapped in the rock as it cooled. This sample is from the Canadas caldera, Teide volcano, Tenerife, Canary Islands.
Model release not required. Property release not required.