@Jacques6 - Metallurgy is amazing when you think about the science behind it. The inventor must have been a really smart person to come up with it. They must have seen metal melting and decided to try to imitate it. Humans imitate nature for a lot of their inventions.
Metal smelting in any form has given humans leaps and bounds in technology. Think of the Ancient Egyptians. They smelted bronze, iron, gold and silver. Most of their weapons were made from bronze and one of the earliest known iron blades was found over there.
When most people think of gold, they think of the golden tombs and golden treasures of Ancient Egypt. Egyptians mastered gold metallurgy early on, which is why they were considered to be such a wealthy nation.
The reason Egypt got invaded so often probably has to do with the fact that they flaunted their gold. They had easier access to it than most countries, so of course other countries would want to get it.
Why work hard mining gold and smelting it, when the Egyptians had done all the work? Honestly, I'm amazed Ancient Egypt survived as long as it did with all the greed back then.