The End Product: Concentrates
The purpose of processing operations was to concentrate the ore up to an average of 60 - 80 per cent for tin.
Low quality concentrates might sometimes be accepted by the smelters but at major price penalties. The differences in the natural occurrence of ores and the amount of broken rock that had to be extracted, processed and smelted to produce a given quality of metal largely explain the differences in their price. For example, Lead was the most commonly occurring and relatively the most easily extracted and processed and so was the cheapest; whereas tin, more sparsely occurring and required great effort to produce a small quantity of finished metal. Therefore tin was five times or more the value of lead per unit of weight.