So much is so unknown.
Further up topic, an interesting statement was made about Earth orbit being the natural temperature for uranium to precipitate out at (giving Earth an unusually high percentage of uranium compared to the rest of the solar system). I have no idea if this is correct or not, but it offers an interesting possibility from a game perspective.
If we assume that all elements start out as a gas or liquid at the sun and naturally precipitate out at the orbital distance where the black body temperature from the sun falls below it's melting point ... Then the elemental table can be arranged by decreasing melting point and plotted by orbit to estimate where the above average concentration of each element would typically be found. This could identify which elements might be available for export on each world in the system. So mercury might have an above average ratio of very high melting point elements (like tungsten) that could drive settlement for commercial exploitation.
Again, this is probably not very accurate, but until large scale mineral exploration begins on moons in the outer solar system, nobody will really be able to prove it to be wrong.