Just a thought, and I could be way off. La Profunda has produced...

Just a thought, and I could be way off. La Profunda has produced 100k tonnes ore which is concentrated down to 38k tonnes of concentrate. 20k tonnes of concentrate graded 14% cobalt and 6% copper (forgetting nickel for now) and 18k tonnes graded 4% cobalt and 20% copper. If you assume (and it's probably a big assumption) and weight the 100k tonnes of mined ore according to concentrate produced, then you get 52.6k tonnes of mined ore concentrated to 14% cobalt and 6% copper and 47.4k tonnes of mined ore concentrated to 4% cobalt and 20% copper. The weighted grades across the two concentrates become 9.26% cobalt and 12.63% copper. A weighted 38k tonnes of comcentrate from 100k of ore, does the mean they were mining an ore body grading 3.52% cobalt and 4.8% copper? Even it's its 50% wrong, it's still 1.76% cobalt, 2.4% copper.