Petroleum and its derivatives are called Black Gold as they are very valuable. It is a term applied to oil or petroleum, which is black when it comes out of the ground and is worth a great deal of money. The word petroleum is derived from Latin words –Petra meaning rock, oleum meaning oil.
Oil is not the only black Gold on the planet. There’s other black Gold that is very wealthy. That is not the answer I’m looking for. Thank you Eric, for your response