I used to work at a mine in Canada (names have been changed here to protect the guilty). One day the controller walked into the manager's office with a stat report sheet from the federal gov't asking for a report on ounces produced that year. The manager took the report sheet and tossed it in the wastebasket in front of the controller! When the startled accountant asked how he could do that, the manager replied, "that is just the gov't bugging us to be their book keepers, there is no law that says we have to fill it in, and no penalty if we don't! We pay our taxes, and that is all they need!"
Don't ask me how these figures get arrived at, but I guess most people are more co-operative.
One other mine I knew used to be operated by a fellow I knew that had retired a few years back. At one time it had produced 95% of Ontario's gold. (true story, but not when he operated it) The gov't had it in its books that the grade was .25 ounces per ton at close down in 1945 and historically it was supposed to be .50 ounces per ton. Well I asked the superintendent what grade he operated at. He replied "better than once ounce, and sometimes much better."
(It makes sense to that area which has many high grade small mines) I asked him how it was that the grade was in the books at .50. He said "well in those days we sold our gold in the United States and did not declare it in Canada." (The mine was on the shore of a lake which straddled the border) He also said that he shut down in during the war when they hit a diabase dyke and the vein got offset and they had no time to drill before breakup (on the water) to re-establish the vein. They were also manpower short during the war, and they could only run one or two shifts a day. They had operated on a strike length of about 300 feet of paying vein in about 800 feet. The manager said they had uncovered a vein in a pit more or less on strike, on an island 1/2 mile away. The grade in a chip sample of that pit was .25 ounces per ton over 7 feet from a published report.
I was up at his cottage on day when I asked the guy when the last time he had worked. He offered that it was at that mine during the war. This was 1975 when I asked him. He looked to be about 70 years old, not much older. I guess he retired young on a silicosis pension.
Interestingly that whole area had mines, still held to this day, that have not produced in 90 years or more. Few of the mills had proper grinding technology, (using stamp mills) and few had good recoveries, some operating at less than 25% recovery. Bear in mind that the long-axis-rotating continuous throughput ball mill was not developed until 1890 and cyanide came along about that time too and was not yet widely used. It was not until Timmins and Kirkland lake were developed (1920 to 1935) that grinding and recovery technology started to be engineered to a high degree and recoveries rose to above 75% on the average.
At the mine I had worked at I conducted a drill program 5 years after it had closed. Previous drillers of some authority degree had extended the vein 1.5 miles to the west and it was marginal and probably a parallel vein. We had worked to a depth of 300 feet on a strike of 800 feet. When I asked the mineral consultants why they did not mine deeper they said that the deposit was mesothermal and did not precipitate down below. It didn't go down. My first drill holes to the east were at a depth of 1000 feet and found the exact same metamorphic grade (greenschist facies eutectic) and we continued it to the east by drilling for 1/4 mile with Visible Gold and a similar 100 foot wide mine-unit structure, productive of 3 veins or 2. I was able to ascertain that it continued, bending around an large intrusive (the experts thought that would be unlikely) and it had surface expression for another 3 miles. Amazingly (well it's not that uncommon) it bent around a peninsula in a massive fold and came all the way back 3 miles on the other side where pits showed mine grade due south of the mine! I wouldn't say all or that any part might be mineable but that is a lot of auriferous structure! To this day not another hole has been punched or an ounce mined. The holes I drilled in which I saw visible gold have not even been assayed. They got sent to a lab but the bill was never paid! Nother story.
In the Southwest States many of the deposits are refractory (resist ordinary recovery) along the Nevada-California trend. Back in the 1890's mills struggled with low recoveries. One mining engineer perfected a method of oxidative process and cyanide recovery that made recoveries skyrocket. He implemented the start of generalized custom milling to miners. This created a gold boom whereby many of the deposits became economic. Eventually this process fell out of favour because of air pollution regulations and the gold fix of the 30's. It was very energy efficient and increased recovery to optimal, but the gov't would not license any more roasting plants as far back as the late 40's.
Interestingly, a professor I know has held patents on sulfur environmental abatement to 99.99% on such processes. It would make many of the refractory deposits very economic and cheap as sulfur is a fuel and contributes to co-generation in no small way, as was demonstrated at Kerr Addison Mine. Such deposits abound in the Pacific Rim, in the SW desert, and in tailings ponds. As recently as 1995, refractory deposits have been receiving negative feasibilities by conventional processes of grind and cyanide. The abatement plant is part of the process and adds energy, but it is about $7 million to build, so at one tenth of an ounce you need perhaps 2 to 3 million tons to pay back in an open pit. As well recent developments in electrical deposition in very dilute fluids, which were thought impossible 5 years ago, have rendered the cleaning of tailings of PPM's of deleterious elements an economic proposition. This allows water quality permits to be obtained, as processes can attain city park levels of purity. This removes a major stumbling block to many riparian rights challenged mines in Canada and the SW US, inoperative or unexpandable since the 50's.
To tie this in with Gold price, for those lost in my milling circuit, suffice to say there is opportunity to mine lodes of lost gold once the price recovers to where you can finance them.
Of all the course I took in mining, the ones I definitely should not have slept through were on how to raise money fast. Some of my critics are apparently more educated in that. It's too bad that it doesn't always get spent in the right places.
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