Petroleum, gold, iron, different gaseous mixtures that make natural gas (used for energy).
Petroleum can be refined and burned as fuel, or it can be made into plastic.
Gold is very malleable, giving it the right proprieties to make coins and works of art. Gold is rare, so its worth alot more than other metals.
Iron is hard and very easy to find. So its cheap and is all over the place. Iron is made into anything from an expensive pen, to a billion dollar sky scraper in Dubai.
