Scientists studying a moon rock have found an unknown mineral, one that illustrates how weathering can occur even in a waterless, airless world. “I saw a couple of particles that I thought were tarnish,” says geoscientist Lawrence Taylor of the University of Tennessee. “It was actually the color of the new mineral.” An exotic mix of iron and silicon, the mineral probably formed in the continual shower of mite-size meteor-ites that strike the moon. These highly energetic particles melt the rocks, vaporizing elements that in turn combine to form substances that never arise under terrestrial conditions. Taylor and his collaborator, postdoc Mahesh Anand, named the mineral hapkeite after physicist Bruce Hapke, who first described the dramatic potential of space weathering in 1973.