I bet that you are on the right track.
Although I think they have found carbon on Mars already, and methane, so perhaps some other type of hydrocarbon.
Although a huge gold discovery would be neat! “GOLD! Thar’s gold in them thar hills!!”
An aside - there are still lots of rich gold deposits in the world. But it takes more money than it is worth to get it out and shipped. I’m guessing the cost of mining on Mars would be....astronomical.
“I’m guessing the cost of mining on Mars would be....astronomical.”
Shipping costs too.
Actually, it is probably easier/more efficient to mine iron there. Future space fleets might be made from Martian steel, because of that advantage.