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Richard's point about lighting and the quantitative versus qualitative approach is very important, but it rather plays down the miner's skill. The "smoky candle stuck in my hat" certainly gives one a different perspective, but it still gives enough light for close work. The issue of discarding lead carbonate ores is one of ignorance. There are C17/18th mine names which suggest that 'white ore' was worked. Similarly, ribs of blende would be avoided because its relative weight is so different to that of galena. Where the mix was intimate then it could only be separated at surface - and then with some difficulty in fines. Mine agents usually talked in quantitative terms because that gave them an idea of how much ore had been blocked-out and how much they would have pay the miners to get it. The qualitative aspect was not ignored, however, because it told smelters how well dressed the concentrates were. Most large mines would make regular assays of their ore - suggesting that 'rack of eye' was not a good measure. You can bet that where smelters bought in their ores - they knew precisely what the lead content was. Mike