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Post by captbob on Jan 30, 2015 9:46:24 GMT -5
Howdy all. I've been buying up pretty much all the decent Stone Canyon jasper rough I can find lately. I want a stash of it and it's also my next tumbling batch - cutting some up as I type this. Much of the Stone Canyon I see (or buy) has a black coating on one or more sides. I'm figuring that as the jasper mass fractured for whatever reason, that this black mineral must have "seeped" into the fissures within the jasper. Maybe it happened some other way, that's just my guess. Here's a picture of a 26 pound piece I bought (eBay) a couple days ago, with the black showing well front lower right. I don't doubt that this black coating (possibly manganese) will be removed when tumbling as it is primarily on the surface of the rocks. But, my question is as to whether there is a way to remove the black from rocks I don't want to slab or tumble. A way short of grinding it off. Maybe some kind of acid bath? I don't have a clue if this is possible, but figure if anyone might know it would be this crowd. I'd like to hear any suggestions, and would love to hear a tried & true solution. Thanks!
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Post by deb193redux on Jan 30, 2015 9:53:09 GMT -5
I think it is a little deeper in the pore space than a surface mineral. If you look at some of the healed fractures, the last brecia event is the black lines/areas. In larger areas the black/dark-dark-green is softer when cutting. It might abraid off. but hard to do w/o shaping stone.
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Post by captbob on Jan 30, 2015 10:21:01 GMT -5
I don't know Daniel, it really seems to just be a surface coating. I have chipped some of the rocks with a hammer and the normal looking Stone Canyon is immediately below the black surface coating. The black doesn't seem to penetrate into the rock at all.
I have muriatic acid (for the pool) but I recall some other acid being used on rocks - maybe hydrochloric? Just wonder if that is worth a shot.
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Post by orrum on Jan 30, 2015 10:30:16 GMT -5
Oxcilic acid??? Spelling is wrong but it's used to clean crystals etc.
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Post by deb193redux on Jan 30, 2015 10:37:09 GMT -5
I just mean it not like a layer of calcite in limestone that can be flaked off. it is likely penetrating .25mm into the stone's pore space, and may be partially silicified.
I see other black lines in your rock (and mine). The reason the stone broke where it did was because this line had not been fully silicified yet. But you could imagine it breaking on the black line I circle.
the black is on its way to being chalcedony/agate just some parts are unhealed (not fully silicified) - usually acid works when you are removing some sort of non-silica mineral. But anything worth a try.
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Post by captbob on Jan 30, 2015 11:35:22 GMT -5
Doing a lot of reading using Google to search and removing manganese (if that's what it is) sounds doable. Quite a bit of relevant information on mindat.org Going to start out slow with concentrated hydrogen peroxide (30%), then try something called Super Iron Out and move up the "bad stuff" scale from there as needed. May take a few tries, but I'll figure something out. Yoda voice: Persevere and succeed you may
Yeah, we'll see about that Yoda! ETA: and thanks orrum I will pick up some oxylic acid as well. I'm reading that takes awhile to work, but who's in a hurry? I'll mix some up and let a piece soak to see how that works.
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blackout5783
starting to spend too much on rocks
Member since November 2011
Posts: 248
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Post by blackout5783 on Jan 30, 2015 12:24:50 GMT -5
Doing a lot of reading using Google to search and removing manganese (if that's what it is) sounds doable. Quite a bit of relevant information on mindat.org Going to start out slow with concentrated hydrogen peroxide (30%), then try something called Super Iron Out and move up the "bad stuff" scale from there as needed. May take a few tries, but I'll figure something out. Yoda voice: Persevere and succeed you may
Yeah, we'll see about that Yoda! Careful with that 30% peroxide. Way more dangerous than super iron out. Wear heavy gloves (neoprene, not rubber) and do not let it come in contact with anything that can burn (oils, solvents, etc.) And NO ACETONE at all. Acetone peroxide (the product of the mix) is a primary high explosive, and unstable at that. Terrorists have used (or tried to) it to make bombs. They've nicknamed it the "Mother of Satan" because it's so unstable and friction /shock sensitive. If you wanted a somewhat more safe option, you could try a 1:1 mix of white vinegar and regular hydrogen peroxide (the brown bottle stuff at the pharmacy). It mixture contains peracetic acid which is a pretty potent oxidizer. You'd still need gloves and a fair dose of caution (and good ventilation), but it won't have a tendency to make things that want to go boom like the 30% peroxide. I haven't personally used the vinegar/peroxide mix, but I've seen some posts about it over on Mindat for cleaning specimens. BTW, if that black stuff is manganese oxide, the super iron out would be the way to go. The oxidizers (at least not the usual ones) wouldn't touch it since it's already oxidized.
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Post by captbob on Jan 30, 2015 12:31:17 GMT -5
Thanks for all that blackout5783 Just heading out the door to get stuff to try. I'll use the Super Iron Out first!
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Post by captbob on Jan 30, 2015 16:55:55 GMT -5
Alrighty... I have a few pieces soaking in a tub of water with the Super Iron Out. Mixed it kinda strong, so we'll see what an overnight soak does. The water is already getting darker, but that may just be some other surface dirts - dunno - thought the rocks were clean.
I should have taken "before" pictures. But, if I think there is a vast improvement in a day or so, I'll just redo the test with pictures next time.
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Post by orrum on Jan 30, 2015 20:23:07 GMT -5
Hey Bob Super Iron Out is Oxylic avid.
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Post by orrum on Jan 30, 2015 20:26:56 GMT -5
You gotta put the super iron out in hot water with the rock. The rock has to be as hot as the water. Otherwise the hot water gets cooled real fast with the cold rocks added. Plus do it outside cause the fumes aren't safe. I put the metal bucket full of rocks and water on a hot plate outside and when hot add the super Iron Out. Leave it simmering a day or so. Then soak a couple more.
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bsky4463
fully equipped rock polisher
Member since September 2013
Posts: 1,696
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Post by bsky4463 on Jan 30, 2015 20:33:16 GMT -5
What orrum said - outside for sure.... I use a dedicated old crockpot. Cheers
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Post by captbob on Jan 30, 2015 22:44:37 GMT -5
The information on the jug it comes in said the vapors were bad, but it also said that you use this stuff to clean stained toilets. Sooo... I'm thinking - how bad can it be??
BAD. Found that out with a quickness! Once the hot water was in I added the super iron out then the test rocks. Wow, the fumes were kinda overwhelming even on the back screen porch. Next trial run will be out in the back yard by the shed where I have electric and can plug in whatever I come up with to keep it warm.
The crock pot is a good idea, I may hit the neighborhood thrift shop tomorrow to find one, but I probably need something much larger. Maybe a turkey roasting pan sitting on an electric skillet. I'll sleep on that.
Thank you all for the schoolin' - this is a new subject for me, but I think it will be easy enough to pass with a little MacGyvering along the way.
Gonna be super happy if it works!
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Post by captbob on Jan 31, 2015 0:27:29 GMT -5
Well this is interesting.
I also put a small black "stained" piece of the stone canyon in a tupperware with a hydrogen peroxide / vinegar mixture and let it sit - been about 10 hours now. Seems the part submerged in this solution has cleaned up rather well.
I'm going to try a different rock starting tomorrow morning and really pay close attention to before & after. This may be a lot easier, and less noxious than the super iron out if it works.
Will report back.
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Post by Rockoonz on Jan 31, 2015 2:44:02 GMT -5
I seem to recall reading that with oxalic acid you need to use glass containers and maybe stainless, not steel iron or aluminum.
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Post by captbob on Jan 31, 2015 9:31:05 GMT -5
I seem to recall reading that with oxalic acid you need to use glass containers and maybe stainless, not steel iron or aluminum. pesky details... which may keep me from being overcome by toxic gasses! Thanks Lee, I'll check on that. Hopefully, I'll figure all this out without blowing myself or anything else up. Probably shouldn't have slept through chemistry class.
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Post by captbob on Jan 31, 2015 9:47:40 GMT -5
okay... the morning rock check is amazing.
Both tests worked.
The rock in the hydrogen peroxide / vinegar solution is almost totally clean. As are the 3 rocks that soaked in the iron out.
I'd call both tests over 90% clean of the black surface coating. With the iron out being maybe even 95% clean.
This manganese (?) is coming off with little effort and with basically no fight at all.
More to follow.
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