With an ability as insane as Li Xiang's, all the ore veins deep underground were his for the taking, like his own private property.
When Li Xiang used his Crystal Vein Armor to mine underground, it was exceptionally stealthy. He didn't have to apply for any permits, and he didn't have to pay taxes.
Of course, these ore veins were just "byproducts" of their search for a special Earth Vein, not the true purpose of their trip.
