Copper is mostly found around 70 feet or even sometimes 100 to 200 feet down in the earth in the copper mines.
Most copper in copper mines are found in copper mines that are only 70 feet deep which is pretty deep but some copper mines may go down much father than that depending on the location of the copper mine.
Copper is found in several locations.
During the Bronze age is when copper was in very high demand and during that time of the Bronze age copper was found in copper mines as deep as 70 feet.
Copper mines can be found in several places such as the USA, China, India and much more places.
China does a lot of copper mining now but the USA used to mine a lot of copper at one time.
There are still a lot of copper ore available to be mined and we likely will never run out of copper at least for another 2,000 to 10,000 years.
Copper is recycled a lot so it would likely never run out at all.