Cited by 6 — present paper summarizes the ore / mineral resource base including the technologies for extraction of rare metals follow a different methodology than Iron. 5.0. Copper. 0.0055. Calcium. 3.6. Zinc. 0.0070. Sodium. 2.8. Cobalt level of 2700 t year, stagnated for years, is being raised to 7700 t possibly by the end of 2011.