You can also try a Wetlands map. Usually has a lot of the different ores/metals, including large marble deposits, ice crystals, igneo, darksteel and the others. Yeah, a lot of water, but if you're looking for ores, it has 'em.

You can get 2k + marble if you go to the taiyi sect easily enough to build ur whole sect out of it

Thanks, I meant to do the same, saved me some time. However, stacks of marble are available in the sect Ruins, random numbers per stack but you can grab 1200+ marble per trip with your first inner sect member(just found out reading in the ACS Foundation Guide from discord) as you can grab 6 stacks per trip to Taiyi ruins. Plus iron, and spirit stone blocks. Just leave the stacks that have a few items and they be randomly regenerated next visit. I only grab stuff with 200+ per stack