Gallery: Hidden Rainbows in Ordinary Rocks

By slicing rocks very thin and using special filters, geologists can turn a drab-looking rock sample into a slice of color. These photographs zoom in on tiny sections of rock just a few millimeters across. The images can tell geologists about the formation and composition of a rock, or, as Italian geoscientist Bernardo Cesare discovered, they can provide a palette for artistic beauty.
Above, a sample of slag (a byproduct from smelting ore into metals) provided by Ivana Angelini. Read the full article.
Rocks aren't the only material that can reveal colors using the technique. This is a fragment of a plastic bag.
This is one of Cesare's favorite images, a type of metamorphic rock called a schist bearing the mineral charoite.
A garnet peridotite from Alpe Arami, Switzerland.
Graphite (the mineral used to make pencil "lead") in a metamorphic rock called a granulite from Kerala, India. The sample was provided by Satish Kumar.
Ocean Jasper from Madagascar is on of Bernardo Cesare's favorite rock micrographs, due to its flower-like patterns.
Charoite-bearing rock from Yakutia, Russia
A granulite (a type of metamorphic rock) from Manitoba, Canada, provided by Martha Growdon.
Crystals in a chunk of lava from Lipari, Italy, take the shape of a heart.
Crystals of the mineral plagioclase in gabbro, an igneous rock.
Ocean Jasper from Madagascar.
Another view of Madagascar Ocean Jasper.
Microfolds in a metamorphic rock called phyllite from the eastern Alps of Italy.
A limestone from Veneto, Italy holds a secret: A coin-shaped fossil, the remains of a marine protozoan called a Nummulite. These fossils are common in rocks around the Mediterranean.
