What is the color of Copper Ore, if there is a typical color ?
Most low-grade copper ores (less than 1% copper) are gray in color. There just isn’t enough copper in the material to give the green color of copper oxides.
the open pit copper mine at Bingham UT has now aged to a yellowish gray.
dd
THANK YOU Mark and Paul.
The first place that I looked for the answer was your MUCH ACCLAIMED fantastic article in the August, 2004 issue of trains Magazine, Mark.
I am modelling an HO copper train in the U.S. around 1940.
I was hoping for a color to differentiate it from my strings of coke, coal, gravel, sand, and iron ore trains.
There are little nuggets all over the place at Magma Junction, Arizona, that have the kind of green discoloration you get with an old oxidized penny. I don’t know if this stuff fell out of some passing ore cars or was used as ballast, or both.
If you want a real interesting load, a mine near McKay ID regularly shipped 1 hopper car of “lead concentrate” every week or so until the mine closed down in the mid-1970’s. The concentrate was finely ground material. To keep it from blowing out of the car, they would cover the load with a couple of feet of course gravel. The concentrate was very heavy, so a fully loaded hopper – even with the gravel topping – would only about 1/2 fill a standard open-top hopper.
There was another reason for the gravel topping. Although the “lead concentrate” did have significant amounts of lead, it assayed out at about 5 - 10% silver. That was the real value in the load. Both the gravel and the “lead concentrate” identification on the manifest were to disguise the true contents.
The railroad was aware of the true value because they sent a clerk out to the mine on the train to personally sign for each shipment.
dd
Now why all the secrecy about the minimal silver content? Silver sells for a few dollars a pound. You will need truck loads of the stuff to make any money and where are you going to get a smelter to fini***he refining process to reclaim the silver and lead? It makes a nice story but better fits into the folklore catagory embellished by employees over time and cold beer than being the real reason for the gravel cap.
The price of silver on 26 Oct 2005 is 7.88 per ounce (not pound). At today’s prices that hopper car had about $ 1/2 million (US). But the price of silver in the 70’s was about 5 times what it is today - so $2.5 million. Thus the efforts.
PS - this isn’t a coffee story - but first hand experience.
dd
Wellll, during most of the 1970s, silver was in the $4-6 range. In 1979 it went up to $34, then spiked briefly at $48/oz in 1980, then back down to the $4-6 range for the next 20 years. The 2004 average price of $6.67 is substantially above the average, 1970-1978., which was closer to $4.
Best regards, Michael Sol
Still, the problem of transporting and smelting the concentrates remain. This is not an operation most people can just do in their back yard Weber grill.
Could the gravel have been something like limestone or clay pellets used as a flux during the final smelting? If not the end result would have been a sizeable pile of gravel at the final destination of the ore unless it could be sold as concrete mix or paving material. That would be challenging account the gravel’s contamination by lead concentrates.
The per pound instead of per ounce was my error. Sorry.