Pentlandite is a yellowish-bronze coloured metal of iron nickel sulfide. It is one of the main ores for Nickel.
Nickel is a chemical element with the symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge.
In certain places, like Afghanistan, Canada, and the USA, they dig underground tunnels and use drills and shovels to harvest the ore, transporting it back to the surface by the cartload.
In most other places, they dig away the surface of the ground, layer by layer, which forms these giant pits.