electrocutus
spending too much on rocks
Member since October 2020
Posts: 331
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Post by electrocutus on Dec 22, 2021 10:07:28 GMT -5
Is this shale? At first I thought it might be slate, but it is too soft (copper penny scratches it pretty easily). They are very "slabby", or I guess the right term is laminated? I picked those up on the shore of Loch Lomond in Scotland this fall. When dry they are just plain dark grey, but I liked them because there was a nice "silvery" shimmer to them when they are wet. I polished them by hand to see what I would get. I could not get a very good shine , probably because of their softness, but the silvery shimmer is very nice. It's hard to capture in photos with a smartphone. thanks.
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wpotterw
spending too much on rocks
Member since September 2016
Posts: 442
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Post by wpotterw on Dec 22, 2021 11:14:20 GMT -5
A couple more samples. I don't think it is shale. Looks to be metamorphosed to some degree and appears to be schistose from the pics that were posted. Too much sparkle for shale.
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electrocutus
spending too much on rocks
Member since October 2020
Posts: 331
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Post by electrocutus on Dec 22, 2021 11:43:08 GMT -5
I don't think it is shale. Looks to be metamorphosed to some degree and appears to be schistose from the pics that were posted. Too much sparkle for shale. Thanks. I think you are right. I had looked up about the geology of the area but still didn't know. I had no idea what schistose was until you pointed it out, but now I looked up some samples online, and many look very similar. It's very pretty :-)
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LazerFlash
Cave Dweller
The more they over-think the plumbing, the easier it is to stop up the toilet.
Member since September 2021
Posts: 550
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Post by LazerFlash on Dec 22, 2021 16:01:45 GMT -5
At first I thought it might be slate, but it is too soft (copper penny scratches it pretty easily). Looks to be metamorphosed to some degree and appears to be schistose from the pics that were posted. Okay, take this with a grain of salt, since there are those on here with far more knowledge than me. But, I recall from my basic high school geology class that a U.S. penny is a Mohs 3. What I've read now online is that schistose runs at 3.5-4, would a penny scratch it easily?
Of course, the caveat is that I am talking about pennies from the previous century.
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electrocutus
spending too much on rocks
Member since October 2020
Posts: 331
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Post by electrocutus on Dec 22, 2021 17:11:42 GMT -5
At first I thought it might be slate, but it is too soft (copper penny scratches it pretty easily). Looks to be metamorphosed to some degree and appears to be schistose from the pics that were posted. Okay, take this with a grain of salt, since there are those on here with far more knowledge than me. But, I recall from my basic high school geology class that a U.S. penny is a Mohs 3. What I've read now online is that schistose runs at 3.5-4, would a penny scratch it easily?
Of course, the caveat is that I am talking about pennies from the previous century.
hmmm... I used a Canadian penny... Is the exchange rate in value the same excahnge rate in hardness? :-)
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