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Post by greig on Aug 21, 2016 22:35:45 GMT -5
I have been cutting some silver ore (found with a metal detector at Cobalt, Ontario). I like these pieces, but I have a project where I need a slice which has a lightening bolt (thin vein) in rock, but I am getting dendritic or solid silver and mixed ores - so I will have to cut some other ones. I have not polished them. Here are a couple of the pieces:
This is a slice of a small rock
This is the rind on the small rock. As you can see, they sometimes don't look like much on the outside.
This is a slice of a larger rock.
I left this piece of the larger rock uncut and it weighs about 2.5 lbs.
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Post by captbob on Aug 21, 2016 23:51:08 GMT -5
Very cool. Don't judge a book by it's cover.
Have you ever polished one, do they take a shine?
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Post by greig on Aug 22, 2016 16:04:18 GMT -5
Very true about not knowing fully what is inside. When the ore was extracted, it usually fractured along the lines with poor visible silver, so many times the outside of the rock is not a good indicator as to the amount of silver inside (whereby it is much better inside). This is why there is so much good silver still to find - if once can metal detect a mine where the old timers separated the rocks for shipping/refining by sight.
Once a sample is isolated, the metal detector can tell you a lot, but with the mixed metals, it can still be confused. We always rub the outside of the rock to try to eyeball some exposed silver, which will shine in sun or shade. The area I metal detect also has quite a bit of nickel and cobalt.
When you ask about polish - do you mean in a tumbler or slabs? With a tumbler, it depends quite a lot on the kind of silver. Dendredic is not the best to tumble because it is more like a bunch of silver crystals, so difficult to make smooth. I am still learning how best to tumble silver, but have found it best to take dendritic out of the tumbler early and just have a rough nugget. Wire silver is horrible to tumble, but so nice to look at, so if suspected to be wire, it should just be etched with acid. The best silver to tumble is the solid stuff - - The high purity silver comes out bright and shiny. If it is a mixed ore, can be a bit grey. The funny thing is - - one of the best things to tumble successfully is nickeline. It tends to come out coppery colored and makes a handsome nugget.
If you are asking about polishing slabs, I don't have the tools to polish them, but have heard they shine up pretty good and unlike tumbling the best pieces are either dendritic or thin vein material. I have heard that you have to be careful machine polishing, because the silver may heat up and smear. If the ore is a mixed metal, the amount of shine will depend of what it contains. Also, after a short while, nickeline and cobalt will get a bit of oxidation (much faster than the silver).
Hope that answered your question. If not, let me know because I can talk about this stuff all day. ;-)
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