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All Of You Rock Hounds- What Is It?


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I found this near an old mine. There was also a smelter in the area about 100 years ago. I think that this is a chunk of the ore that they were mining. When I picked it up I thought that it was a chunk of copper ore or a native copper nugget. I have found copper nuggets before and this is what they look and feel like. Quite heavy. My digital scale only goes to 3oz and this overloads it. The pic is of both sides next to a crusty quarter and then a pic of the end. When I was brushing it off a small piece broke off the end and revealed silver color under the blue patina. I then hit the jagged edge on my grinder and, as you can see, more silver color. I don't want to ruin the specimen by soaking in acid or anything so I thought I would ask you rock hounds for some ideas. Oh, it rings up as a mid-tone #45 on my Nokta Fores CoRe which is low for silver or copper. Any ideas would be appreciated.

 

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End showing silver color. Expected copper color.

 

Thanks!

 

Dean

 

 

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Thanks for the reply, Root...

 

What is the silver colored metal? I've  found lots of  native copper nuggets and they have always been " copper" colored.

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Did it put off a loud signal on your detector?

It may have some silver on it as well. Green is usually some kind of copper oxide but I found a piece of ore that I posted in Rob's forum that looked like a big mix of copper, quartz and silver. Just didn't have time to erode yet I guess.

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Tortuga, 

Yes, it makes my detector scream. The VDI # comes up at 45 which is low if one is expecting copper or silver. Copper comes in at 82 and silver at 90. I tested some of my other copper and silver nuggets and they come in with high VDI #s.

 

Galena. Good thought, Root. Thanks.

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No, not Galena, Its likely Cuprite, a conductive copper mineral and fairly common in many copper deposits. It oxidizes to malachite (as you see on the outside). It can be red to a dark silver in color. It sounds off on a metal detector and a piece like you have may be a fun souvenir, but its not worth anything.

In some parts of Arizona, these are known as green turds. Because the mineral actually conducts electricity, they sound off from depth, unlike hot rocks.

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No, not Galena, Its likely Cuprite, a conductive copper mineral and fairly common in many copper deposits. It oxidizes to malachite (as you see on the outside). It can be red to a dark silver in color. It sounds off on a metal detector and a piece like you have may be a fun souvenir, but its not worth anything.

In some parts of Arizona, these are known as green turds. Because the mineral actually conducts electricity, they sound off from depth, unlike hot rocks.

Must be the same stuff I found. I posted the specimen here- http://forums.nuggethunting.com/index.php?/topic/11666-copper-nugget/#entry81648

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Yes, mostly likely your specimen is cuprite, though you cant see it in any of the pictures. The visible red stuff on the surface of your specimen is not Cuprite - probably some sort or iron rich silica. Its really normal that in many places where the cuprite has eroded out of a vein and washed down into some gravels or hillside wash, that the cuprite will get coated by weathering with a blue to green coating of copper minerals, and the cuprite will be in the middle.

Yes, because its conductive like a piece of metal, you can dig cuprite specimens at afoot or two of depth - a big piece even deeper. Tortuga - if you want to be sure you will need to crack the piece open to see the interior. If its a kind of dark red to red-silver kind of color - its cuprite. See:  http://nevada-outback-gems.com/mineral_information/cuprite_mineral_info.htm

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Thank you, Chris! Very informative.

Although I like the specimen the way it is, could it be treated with some sort of acid solution to make it look more like the ones in your pictures? If so, what would you recommend? Thanks!

 

Dean

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