To be honest, Feng Jun has seriously prepared for extracting resources from the mobile phone's dimension.
Much like in those urban novels from Qidian, where someone knows they will be reborn and needs to remember useful information, he's made various hypotheses to transfer resources.
So he knows a lot about many metals, especially platinum group elements, which he's studied in depth.
Why delve deep? Because platinum group metals are extremely expensive, with rhodium being the most expensive metal on Earth, having a crust abundance of only one part per billion! Palladium is the next most expensive, and other metals aren't cheap either.
More importantly, while Huaxia's rare earth metal reserves are said to be the largest in the world, its platinum group metal reserves aren't substantial!
Therefore, discovering a platinum group metal mine means no need for hesitation.
