At the foot of Mount Sobo lie the remains of the Obira mine. From its opening in 1617 until its closing in 1954, it had been flourishing as the leading Japanese mine. Apart from Obira, there are the and the on the side of Ōita Prefecture as well as the and on the side of Miyazaki Prefecture. The mines produce scarce minerals like copper, tin, lead, manganese and quartz.