Mars’s chrome dunes revealed: frost-coated basalt sands look metallic

ESA’s Mars Express images show a vast field of dark basaltic-sand dunes in Kaiser Crater that look chrome-like when coated with seasonal CO2 frost. The illusion comes from light interacting with dark sand and bright frost, not actual metal. The dunes, spanning kilometers and more than 100 meters tall, form in a crater that traps sand, highlighting the power of Martian winds in a thin atmosphere and offering clues about Mars’ past climate and geological history.