Need to search and make decision. Comment from PHS (from issue #98):
I think "crude" is better than coarse. I hate to raise this, but this brings up once again the problem of whether fin is better translated in this case by pure. The "finest" metal one can find is rather different than the "purest". This entry seems pretty clearly to mean the purest metal (in the sense of copper alloy "metal", not generic metal), because it goes on to say that finest means a larger amount of copper. I'm not sure how to deal with this. Have we used pure to translate "fin" in the case of silver and tin? I'm pretty sure we have, but it's worth searching selectively.
If this is still a question. We made a decision: translate as "fine"