Glass.

... a sublime scene to consider, with endless glass ridges and hills rolling off beneath stars and red dust storms, slippery to the touch, as hard as bedrock, cold, perhaps glistening and prismatic inside with distorted reflections of constellations, like blisters of light on a television screen coextensive with the surface of the planet. You could slide from one hill to the next, for hours—for days—alone on a frozen ocean of self-reflecting landforms, dizzy with the images locked within.

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