Lanmannalaguar, Iceland:
is filled with banks of rocks colored by hydrothermal alteration from rivers running through the area. Some of the rocks were green, like chlorite, some were purple manganese, and I crossed a stream to pull red from the rock wall. A thin coat of red dust combined with the water on my hands. The mixture sank into the lines in my palms, looking like I was stained with blood.
Mars:
is red because of nanophase mineral dust covering its surface. Some of it is poorly crystalline hematite and maghemite and lepidoctoite that is too small to cling to rock, and the wind plucks it off of basalt and carries it across the planet. All of it is iron oxide, blown from basaltic surfaces and deposited in piles below thin atmosphere.