My point stands, why would you have to qualify a purity with a...

My point stands, why would you have to qualify a purity with a time period. The answer is obviously because it's not a purity, it's a recovery.

Now metallurgists often use the term extraction because it's not recovered yet it's only extracted into solution given that it's a leaching process. So we use the term extraction for an intra process recovery.

Say for example you have a copper heap leach, you might get 90% extraction to solution and of that you get 90% to product, your recovery is then 81%, but your leach extraction is 90%. Your copper grade might still be 99%