There's gems in them thar craters!

The Mars Global Surveyor has detected a 30,000 square kilometer area rich with surface olivine outcroppings in the Nili Fossae region of Mars. Olivine is widely used in jewelry and on Earth mostly takes the form of peridot, the birthstone for August and Leo.

Peridot (pronounced pair-a-doe), or precious olivine, is a volcanic gemstone that was once treasured by native Hawaiians as the tears of the Goddess-of-Fire, Pele. [...] In ancient Egypt, peridot was mined on an island called Zeberget. Mining was done at night because legend said that peridot could not be easily seen during the day, but its pale iridescent green was easily illuminated by lamplight at night. It was for this characteristic that the Romans called peridot the "evening emerald." Peridot later was also often used to decorate medieval churches, and was probably carried back to Europe by the Crusaders. Large peridots, more than 200 carats in size, adorn the shrine of the Three Magi at the Cologne Cathedral.

Because it breaks down quickly when exposed to wet weather, the amount of unweathered olivine on the surface of Mars could provide clues as to how long Mars has been a dry planet, though scientists would need to determine whether it was thrust to the surface relatively recently or during the impact that created the crater about 3.6 billion years ago. Perhaps more importantly, this discovery means that the Martians can pay for the reconstruction of their planet after we liberate them.