The drop to 64.057 million tonnes came as several major operations remained fully or partially shut down in the second quarter following a deadly dam burst at the Corrego do Feijão mine.
Proven and probable copper mineral reserves increased by 21% since the end of 2018 to 11.8 billion pounds, while gold mineral reserves gained 12% to reach 7.4 million ounces.
Nearly 25 asset management firms and some pension funds are seeking compensation for losses derived from Vale's plummeting share price since the disaster.