Why is Mars Red?

Universe Today writes Why is Mars Red? New Study Offers Surprises

"Is Mars red due to rocks being rusted by the water that once flooded the red planet? And is the only explanation for the hematite found by Mars orbiters and studied by the Mars Exploration rovers is that water once was present in volumes on Mars? Not necessarily, says a new study. Research done by Dr. Jonathan Merrison at the Aarhus Mars Simulation Laboratory in Denmark shows that the red dust that covers Mars may be formed by ongoing grinding of surface rocks. Liquid water need not have played any significant role in the red dust formation process."

"In their recent laboratory study, the scientists at the Mars Simulation Laboratory have pioneered a novel technique to simulate the sand transport on Mars. They hermetically sealed sand (quartz) t samples in glass flasks and mechanically ‘tumbled’ them for several months, turning each flask ten million times. After gently tumbling pure quartz sand for seven months, almost 10% of the sand had been reduced to dust. When scientists added powdered magnetite, an iron oxide present in Martian basalt, to the flasks they were surprised to see it getting redder as the flasks were tumbled."