TARKWA, Ghana (Reuters) -As the afternoon sun beats down on Gold Fields' sprawling Tarkwa gold mine in southwestern Ghana, three men launch a drone into the clear sky, its cameras scanning the lush 210-square-kilometer tract for intruders. In West Africa, three to five million people depend on unregulated mining, accounting for approximately 30% of its gold production, other industry data show, serving as economic lifelines in a region with few formal employment opportunities.