Mysterious dark spots on Mars are made of glass

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Mysterious dark spots on Mars are made of glass

In the northern lowlands of Mars, there are vast regions that are darker than the normal red, sandy areas. Other dark regions on Mars are made of basalt, but these are different. These are nearly pure glass, forged in the fires of ancient volcanos.

Briony Horgan and Jim Bell of Arizona State University in Tempe analysed near-infrared spectra of the regions, gathered by the Mars Express orbiter. They found absorption bands characteristic of the iron in volcanic glass, a shiny substance similar to obsidian that forms when magma cools too fast for its minerals to crystallise (Geology, DOI: 10.1130/G32755.1).

The glass likely takes the form of sand-sized grains, as it does in glass-rich fields in Iceland. The spectra suggest the grains are coated with silica-rich “rinds”.

On Earth, such rinds coat volcanic glass weathered by water. How the glassy grains formed on Mars is unknown, but Horgan says magma from Martian volcanoes interacting with water ice and snow is a possibility. That would make these regions (pictured right) potential hotspots for alien life because they would have held chemical-rich water - a key ingredient for life.

Via