Prospecting in shale-heavy areas

[AuSomeness]

Hello all,

I have a question about prospecting in shale-heavy areas. Last year, I broke up some shale and panned out what I could find. The water turned a bit gray'ish, and I was concerned that there may be some heavy metals (i.e. mercury) or something else unknown in it. I did find some chunks of shiny material. It makes the 'ca-ting' sound like gold does in a vial. I'll post some pics of this shortly. My questions are:

(1) Are there any dangers prospecting in this type of material (shale or this type of rock, especially in California / the Sierra Nevada / Motherlode)
(2) What might one find in this material? I'm curious about the "metals" I have found, which are reddish in color.

I'll post pics as soon as I can.

Thanks!

 

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[AuSomeness]

Your " Shale" may be slate. What color? The gray material is its decomposed self that has settled in the cracks. Kind of a gun metal color right. Those are pyrite crystals. You will find them in good gold ore and in the wall rock I.E Slate http://www.johnbetts-fineminerals.com/jhbnyc/mineralmuseum/8513.jpg
Vs the pyrites typically found in shale https://www.google.com/search?q=sha...Q_AUoAg#tbm=isch&q=shale+with+pyrite+crystals

The original host-rock these crystals was in was actually more of a black color, thinly-layered, and brittle. That's why I called it shale. Does that sound right? I do believe you are correct in that I did confuse the two with the new material I found, which is slate! You hit the nail on the head with your examples. It's incredible what one can learn. Many thanks for the reply!

 

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[AuSomeness]

Pyrite crystals.

It looks like you are right, DDancer. I am surprised at how different these crystals look from the free-floating stuff you find in rivers. Amazing! Thanks for the reply.

 

[DDancer]

No worries AU Panned plenty of it and knocked it outta alota rocks as well. If you finding that then if there is gold it'll be right along with the pyrites. As others have pointed out arsenic is not a problem provided you don't eat it or drink the water Placer gold in slates and shales likes to work down into the cracks and often gets pretty flattened out in the process. Decomposed slate is the best area to look and sniping tools are a plus. Good luck and heavy pans.

 

[GoldpannerDave]

Thanks for the info, GoldpannerDave. I tend to play it safe.

Then be careful of what California wines you drink. Some have higher than 10 ppb (amount allowed in water). The 10 ppb is 0.01 mg/kg, well below the LD50. Still over 80 wines sold in California for $5-$10 a bottle have between 10 and 50 ppb.

Canada has a wine standard, the US doesn't and using the drinking water level isn't really a good standard for wine for a number of reasons. Canada's standard is about 10 times the US drinking water standard. All the wines passed Canada's standard, so it is really not too big a deal. Just thought I would mention it just in case....

Arsenic In California Wines: Should Drinkers Be Concerned? : The Salt : NPR

 

[goldenmojo]

There can be Arsenopyrite in shale formations and it can be in higher levels. It is common throughout the Motherlode along with Asbestos. Don't eat either of them. Other than that you should be OK. Also don't vaporize mercury and inhale it. Don't drop large cobbles on your big toe, either singly or in multiple combinations.

 

[AuSomeness]

There can be Arsenopyrite in shale formations and it can be in higher levels. It is common throughout the Motherlode along with Asbestos. Don't eat either of them.

Are you _sure_? It looks SO TASTY!

 

[reptwar1]

I've been dealing with the same stuff. Has a silvery coating