Where it is
Coal turns up near the surface. Copper comes a little deeper, then iron, and gold deepest of all. Caves cut through the pockets, so they are the way down.
Spotting it
The rock around ore is faintly stained: greenish for copper, rusty for iron, sooty for coal and pale quartz veins for gold. The stain is strongest right at the ore.
Mining and smelting
Break ore with a maul. Coal is ready to use. Copper, iron and gold have to go through the Smelter first.