Earth's Top Elements
23-Sep-94 12:37:31
Sb: #146811-Earth's Top Elements
Fm: Bill Combs 73524,2651
To: Lanny R. Ream 73512,1163
>> . . . up until about the 1950s gold could only be mined if there >> was
greater than around a half ounce per ton of rock (+ or –
>> depending on the deposit), but now deposits are being mined that >> have
less than 0.3 ounces per ton.
Are there any other examples of such effecienciy gains that come to mind,
perhaps in other minerals?