Why copper-bearing rocks here, but not there?
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Re: Why copper-bearing rocks here, but not there?
#2I recently did a backpacking trip in the Grand Canyon that included Horseshoe Mesa. There are old copper mines there, and beautiful green and blue copper-bearing rocks visible. I asked (in a facebook forum), why just in that one place and not other places in the Grand Canyon, given how the rock layers in the Grand Canyon tend to repeat themselves for miles and miles. The url is what somebody posted as the answer. It was so satifying to have a question and have it be so thoroughly answered.
Re: Why copper-bearing rocks here, but not there?
#3The top pic appears to show a steel barrier around the mineshaft opening, although it also looks roughly like a multi-level "Chinese gold washing machine."
The latter is a low-cast static set of table(s) that water can wash metal flakes with no moving parts, and is popular for its low cost or use in areas with no mechanicl parts supply. So gravity is used to separate materials, similar to how river bends make alluvial gold deposits. Early ones were made of wood, but steel would also work.
You can see YT videos of a similar design in the defunct Cornwall tin mine.
(In ancient/olden times, the main industrial metal was bronze, alloyed from copper and tin. Tin is very rare since it has an odd atomic number, with the historical mines being in Afghanistan and Cornwall. Before the Iron Age, Cornwall could have been the "El Dorado" of its time. Iron/steel is found everywhere on earth except Japan, so steel democratized industry across Europe and Asia, but Japan had to start WW2 for it.)
(Most gold mining is collecting flakes, not nuggets. 1 gram per ton is usually considered commercially viable, and more makes it dramatically moreso.)
Re: Why copper-bearing rocks here, but not there?
#4The top pic appears to show a steel barrier around the mineshaft opening, although it also looks roughly like a multi-level "Chinese gold washing machine." The latter is a low-cast static set of table(s) that water can wash metal flakes with no moving parts, and is popular for its low cost or use in areas with no mechanicl parts supply. So gravity is used to separate materials, similar to how river bends make alluvia…
I mentioned gold above because one of the largest gold deposits in the world was formed as explained in the article (gold-laden mineralized water forced upwards through vents) in the same area.
It sounds strange that water can push gold upwards, but the proof is streaks of gold in multiple layers of quartz across a wide area in a number of AZ locations. So there's no nuggets, but when the ore is crushed, there's gold powder and flakes.
Re: Why copper-bearing rocks here, but not there?
#5The top pic appears to show a steel barrier around the mineshaft opening, although it also looks roughly like a multi-level "Chinese gold washing machine." The latter is a low-cast static set of table(s) that water can wash metal flakes with no moving parts, and is popular for its low cost or use in areas with no mechanicl parts supply. So gravity is used to separate materials, similar to how river bends make alluvia…
The steel barrier looks like the typical ones the BLM uses to seal off mines so people cannot enter