I was recently listening to a history show and the topic of Bulgarian expansion in the 8th-9th century came up. At some point the guest proffessor stated that at the time rulers werent as concerned with natural resources in newly conquered lands, rather the indigenous population, that could later be taxed, conscriped, etc. However resources like iron, copper, silver, gold, salt, etc were surely also important so how did people back then probe for them, considering they're hidden so far underground?
I can't speak for all of history, but in 1492-93, Columbus kept a journal that is partially available today. Parts were directly transcribed and others paraphrased. The book is simply "The Journal of Christopher Columbus"
In it, he makes landfall in the Caribbean, and his primary goal is seeking gold. He mentions many times that the natives claim to have mines of gold, and he discovers a river that has small gold pieces tumbling from its mouth, perhaps washed down from a mountain. He names the river Rio Del Oro.
So from this we see that native Carribeaners had the knowledge to make shallow mines, and found gold in riverbeds often. Though, by Columbus own account, they did not prescribe much value to the ore, and wore small pieces as jewelry.
They willingly traded it for inconsequential Spaniard trinkets, as they believed the men had sailed from heaven.
However, they were aware of gold and silver as metals. But beyond decorative uses, naught. There is no evidence in his journal they had ever weaponized it, though they expressed great wonder when Columbus fired Lombards into the sea for them