Three regions are named in the Bible as being rich in minerals like copper and gold: Havilah at the source of the Nile in Kush (Genesis 2:11); Dedan in southwestern Arabia, and Ophir, south of Dedan.
The region of Dedan and Ophir is riddled with lava caves dating to many thousands of years ago. The archaic populations of Dedan and Ophir lived in these caves and collected epithermal gold. This is gold that is mined close to the surface because it has been brought up by volcanism.
Scientists have been studying this area. They are especially interested in the lava caves of Harrat Khaybar. Here researchers have found hundreds of stone walls surrounding large basaltic lava fields. The largest of the walls reaches almost 1,700 feet long. The stone walls were built during active volcanism.
The lava caves and walls of Harrat Khaybar (Arabic for "White Mountain") are in the news today. Scientists have known about this region for 30 years. This is the region of biblical Dedan and Ophir, described as rich in precious metals. This is probably the oldest known site of recovery of copper and gold, and the miners lived in the caves, many of which collapsed long ago. Ophir was one the sons of Joktan (Gen. 10:26-28). The Joktanite clans still live in this region of Arabia.
This area of Saudi Arabia and Yemen is a site for porphyry copper and epithermal gold deposits captured by people living in the caves.
In 1946 an inscribed pottery shard was found at Tell Qasile (Tel Aviv) dating to the eight century BC. The Paleo-Hebrew inscription says, "gold of Ophir for Beth-Horon [...] 30 shekels." This, and other such finds, confirm that gold was exported from Ophir.
Every three years Solomon received tribute of gold, silver, sandalwood, precious stones, ivory, apes and peacocks from Ophir. Solomon's navy traveled to Ophir, taking "four hundred and twenty talents of gold from there" (1 Kin. 9:26-28; 22:48; 2 Chr. 8:17-18; 9:10).
Related reading: The Afro-Arabian Dedanites; The Gold of Ophir; Kushite Gold; The Lava Caves of Khaybar in Saudi Arabia; The Religious Symbolism of Gold; The Lava Fields of Saudi Arabia