In theory Mars can put stuff in orbit for a much lower cost than Earth can. The delta v is so much lower that you could supply Earth orbit from Mars with less fuel than launching from Earth.
Great, here's some more Martian rocks for space. We don't have a lot of variety here on Mars, but what we do have, we've got plenty of it. We got some red rocks, some slightly less red rocks, we got some red dust, we got some red sand. Is that what we really want to launch into orbit?
Mars has water (probably, or there won’t be any colonies), and CO2. Water, Oxygen, Hydrogen and Methane, all of which there could be a demand for in orbit.
But according to GP, those rocks are really expensive to get off the ground, so, enjoy these nice Martian rocks instead. They're the generics to your name brand.
