Finding copper in the tailings pile

in #rockhound2 years ago

Hello, and welcome to my page, eh!

During the second week of August, I took a trip up to the Keweenaw peninsula of Upper Michigan for 5 days, partly to attend an annual event, and partly to do the tourist thing. The Keweenaw, also known as the copper country, is a peninsula that sticks up into Lake Superior from Upper Michigan. It's called the copper country because of all the copper mines that were located in the area. It was, at one time, the source of most of the copper that was mined in the United States. The area had been surface mined by the indigenous people of the area for several thousand years, and once the European explorers discovered the copper deposits, large scale mining began. Large scale mining of copper in the area began as far back as the 1840s and continued until about the 1980s or so when the price of copper declined and put the remaining mines out of business.

There are still some signs of even the oldest mines in the area, mostly in the form of tailing piles. On some sites, there are still remains of some of the buildings that were built with rock walls, though many of those walls have long since collapsed into piles of rubble. There are a few mine sites that are open to public viewing, usually because of preservation efforts.

One of the more popular things for "rock hounds" to do when they visit the Keweenaw, besides looking for agates on the beaches, is to look for copper. There are still a few places where you can find bits of what's called "float copper", which is a mass of copper sitting on the ground, or buried not very deeply. These bits of float copper can range from a few ounces to several tons. There are several massive specimens of float copper on display at various places, including the museum on the campus of Michigan Technological University in Houghton, MI.

Another popular place to find bits of copper is in the tailing piles of the older mines from the 1800s. Back then, mining technology was not sufficient to extract the thin veins of copper that occurred in the rock in small amounts. The miners looked for the larger veins of copper, and the copper masses in the rock, they were easier to process for the copper once brought up to the surface. Mush of the smaller veins were considered to be "poor rock" and were discarded in the tailing piles along with the non copper bearing rock that had to be removed from the mine to get to the better copper deposits.

Hunting for bits of copper in the tailing piles has become a fairly popular activity in the places where it is allowed. Some of the old tailing piles are on private property and rock hounds are not allowed to hunt on those piles. However, there are several piles that are on public property and those piles are accessible. The favorite way for many people to search for copper in the tailing piles is with a metal detector. A good metal detector will help with finding copper, but you can also find it without a detector if you know what you're looking for.

I was exploring a couple of the tailing piles on my vacation and ran into several people who were searching the piles. In the course of conversation, they showed me some of their pieces that they had found, and that showed me what to look for while searching the piles. I must say, it's not easy finding copper without a detector, but I did manage to find a few pieces. Most of what is found is just small pieces, but every now and then, a nice piece is still found in the piles.

First, let's take a look at a tailing pile from a typical 1800s copper mine. This is the top of the upper tailing pile at the Central mine, one of the largest producers of copper in the late 1800s in the Keweenaw.

There were several shafts at the Central mine complex, going up the hill. There are 3 major tailing piles. The county road commission has crushed a lot of the lower pile for gravel for their road work over the years, and what's left of that pile is not available for searching. The other 2 piles can be accessed currently.

On the last day of my trip, I stopped at the tailing piles at the Cliff mine, another mine from the 1800s. This is a picture of the tailing piles at the Cliff sight from several years ago, I don't have any current pictures. You can just barely see the top of the piles through the trees below the cliffs.
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I spent the afternoon looking for some pieces of copper there and found a decent amount, which I consider to be really good luck for not having a metal detector. I would consider this rock to be my best find. There's copper sticking out of both ends of the rock, and I believe the vein runs all the way through the rock. I'm sure it's a thin vein through the rock, but it's still a good find for me.

A couple closeups of the rock. This picture shows the lump of copper sticking out of 1 end of the rock.

There's a thin piece of copper, like foil, sticking out of another spot on the rock.

Here's some of the smaller pieces of rock that I found that have copper in them.

I decided to try to clean up a few of the smaller pieces of ore that I found to see if I could get a better look at the copper. I chose these pieces, along with several others.

I soaked the pieces of rock in vinegar for several days, hoping it would remove some of the rock and clean the copper on the surface of the rocks. The vinegar turns a nice blueish color from the copper oxide.

The results were perhaps not quite as good as I had hoped for, but they did clean up the visible copper and made it obvious when you look at the rocks. These are the best samples from that process.

I have more pieces of the rock soaking in the vinegar to try to clean them a bit better. I may have to use a stronger acid to dissolve more of the rock, I just have to find an acid that doesn't affect the copper. I know there are several types of acid that will work, some more nasty than others. I would prefer to use the mildest acid that will work. That still needs more research.

I will write another post once I get some further results, and I'll also show you a few other rocks I found in the tailing pile.
That's all I have for this post, thanks for stopping by to check it out!

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Is that a good spot to find turquoise as well?

I don't think there's any turquoise in that area, at least I've never heard of any being found.

I used to be able to find turquoise at the copper queen mine in bizbee arizona. The tailing piles there had all kinds of different minerals in them. Probably toxins as well.

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I'm not surprised, the southwest has a lot of turquoise in it's mineral formations.
There are a couple of copper mines up here that contain arsenic in the tailings piles. I don't remember the mineral it comes from, but it's not found in any quantity in most of the tailings piles, just a few of the mines.

In a related activity I collected copper pennies before they were declared non legal tender as they are worth about 2.5x the face value, same with the nickels worth at least 1.7x face. Commodity value that is. I get the feeling because the terrible long term effects of inflation we will be forced back to a Sound money system hence my stacking silver coin.

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I have a lot of older Canadian pennies, I've been collecting them for about 40 years or so. We get them in change sometimes here in Upper Michigan.
The U. S. quit making real copper pennies in 1981 I believe. Everything since then is copper clad base metal. I have a few pounds of pre 1981 pennies. :-)


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I liked the idea of vinegar to clean the copper so it could be seen better. That was interesting learning about float copper and the copper mines.

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