Greyhav, I must agree with you mostly. Having worked in the mining industry, off, and on fior several years, (since 1940), I agree that silver and gold are a "by-product" of the copper mining. In Arizona, and other areas, the low-grade mining of copper does produce both gold, and silver. ASARCO mentioned, several years ago that they got over $52,000. in silver from the.004% copper mining. They did NOT mention how much gold was recovered!. Nor did they say how much "moly" was recovered, but I know from personal observation that they shipped box-car loads in 55-gal drums, ( about 950 lbs each) about 10-15 cars a month. I don't recall how many drums to a box-car. This was in '45-'46, when copper was $0.019/ lb. Millwrights got $3.95/hour.
Dick