Whether or not we head to the asteroid belt before Mars, one thing is clear–while we may have the means to land upon and (hopefully) sift the metal from “the rubble” (or useless rocky material), we probably will be unable to inexpensively melt the metals on site.
Even though lasers are always an option, future colonists may not be too thrilled with using extra power to melt down the space metals, as that would only add to the overall cost of shipping the material elsewhere.
While some may be content to pass the cost onto the customer, it may be cheaper (and wiser) to ship the metals to the red planet in order to have the metals melted down via Martian sunlight.
Since Martian sunlight operates at half the strength of Earth’s, the solar furnace would probably have to be slightly altered to achieve the same strength as its bluer big brother.
Although some may suggest that the future asteroid mining industry could simply ship the metals to Earth, it may be wiser to divert the route towards Mars, as the red planet orbits about 100 million kilometers closer (at Aphelion) than Earth.
Martian colonists would also have the advantage of utilizing the crimson worlds two orbiting moons, allowing mining fleets to melt their metals upon either Phobos or Deimos without having to land on the Martian surface (which has a fairly steep gravity well).
Either way, Mars may play a critical role in our quest to colonize the solar system (which may make it a prime spot for future real estate).