"It is, nonetheless, a sublime scene to consider." (Image by Glenn J. Mason.)

From a post on that wonderful BLDGBLOG, a post about the glass-covered surfaces of Mars:

“More than 10 million square kilometers of landscape on the surface of Mars, a region nearly the size of Europe, is made of glass—specifically volcanic glass, ‘a shiny substance similar to obsidian that forms when magma cools too fast for its minerals to crystallize.’

In a paper called ‘Widespread Weathered Glass On the Surface of Mars,’ authors Briony Horgan and James F. Bell III, from the School of Earth and Space Exploration at Arizona State University, go on to suggest that ‘the ubiquitous dusty mantle covering much of the northern plains [of Mars] may obscure more extensive glass deposits’ yet to mapped.

Although it’s worth emphasizing that this glass is present mostly in the form of ‘Eolian’ grains—that is, small pieces of windblown sand accumulating in dune fields—it is, nonetheless, a sublime scene to consider.”