A machine is employed for recovering heavy metals and precious or semi-precious minerals, such as gold, copper, lead, diamonds, and garnets from placer, or hard rock ore. The machine employs a cylindrical, annular outer drum mounted for rotation at an inclination to the horizontal and including at least one spiral vane extending the length of its inner surface. A cylindrical, annular inner barrel is mounted within the drum and has an upper fragmentation section, an intermediate screened section, and a lower discharge section.