Help mindat.org|Log In|Register|
Home PageMindat NewsThe Mindat ManualHistory of MindatCopyright StatusManagement TeamContact UsAdvertise on Mindat
Donate to MindatSponsor a PageSponsored PagesTop Available PagesMindat AdvertisersAdvertise on MindatThe Mindat Store
Minerals by PropertiesMinerals by ChemistryRandom MineralSearch by minIDLocalities Near MeSearch GlossaryMore Search Options
Search For:
Mineral Name:
Locality Name:
Keyword(s):
 
The Mindat ManualAdd a New PhotoRate PhotosLocality Edit ReportCoordinate Completion ReportAdd Glossary Item
StatisticsThe ElementsMember ListBooks & MagazinesMineral Shows & EventsThe Mindat DirectoryHow to Link to MindatDevice Settings
Photo SearchPhoto GalleriesNew Photos TodayNew Photos YesterdayMembers' Photo GalleriesPast Photo of the Day Gallery
bannerbannerbannerbannerbannerbanner

Cleaning native copper

Posted by Kyle Eastman  
avatar
Kyle Eastman February 17, 2006 12:09AM
This last summer I collected some excellent native copper specimens from a commercial copper mine called the Teutonic Bore in Western Australia. Some of the pieces are covered in bright green malachite which is quite attractive, however others(in my opinion) would benefit from having the malachite etched off to better display the crystals of the copper. What is the best way to go about doing this?
-Kyle
avatar
CaptPaul February 17, 2006 03:39AM
Kyle,

Are you sure it's malachite, or just the green tarnish that forms on copper??

One of the most common (and inexpensive) ways is to go to your local hardware store and buy muriatic acid and soak the pieces in that. However, this method is best used when there are NO crystals present and you don't really care about anything except removing tarnish or if you want to remove any carbonate (calcium, etc...) from the piece. If you are cleaning pieces with crystals, by all means, don't!! You run the risk of damaging the crystal faces and ultimately ruining the asthetic quality of the piece, at least in my opinion. I know you can also use sulfamic acid (coffee pot cleaner) to clean copper, although it is a much slower process it's also a much safer one to the copper; not as likely to etch.

CaptPaul
avatar
Kyle Eastman February 17, 2006 03:39PM
Thanks!
I am fairly sure it is malachite, but not 100%. I have actually tried muriatic acid, and it cleans fairly well, but some sort of coating always seems to return after I take the specimens out of the acid. I will not etch pieces with crystals until I have a reliable techinque to do so. That coffee pot cleaner idea sounds like a good one.
-Kyle
avatar
David Von Bargen February 17, 2006 05:44PM
After you take the specimen out of the acid bath, you do need to neutralise the specimen. Soaking in a baking soda solution will deactivate any remaining acid.
avatar
CaptPaul February 17, 2006 08:41PM
Kyle,

What we always did in Michigan after we cleaned our copper was to dip the pieces in something called "Copper Brite", which is a mixture of chromic acid and other chemicals. What this does is put a real thin coating on the specimen to keep it from oxidizing again.

Another trick to clean copper (and silver too) is to dip it in TarnX, which I have found won't etch crystals. If you can't find any of these chemicals, another old trick is to simply rub the crystals with your fingers providing you can do so without cutting yourself winking smiley
avatar
Kyle Eastman February 18, 2006 07:14PM
Many thanks again for all the useful info! I'll see if I can find Copper Bright and TarnX. The crystals seem to be all intergrown, some of them forming branch-like aggregates, which would look nice all shined up. Most of the crystalline specimens are too small to effectively clean with my fingers, and unfortunately most of the larger pieces appear already to have suffered some chemical weathering. I'll see if I can post pictures once I find a reliable cleaning technique. Thanks!
avatar
Barry Strieter February 23, 2008 06:54PM
I found some Copper up in the Upper part of Michigan, I would like to clean it It is with some other type of stone, Can I use mutiatic acid to clen it.
avatar
Alfredo Petrov February 24, 2008 04:39AM
Coca Cola removes secondary oxidation products from native copper.

(Removes apatite from teeth too, in case you want to switch to ceramic teeth.)
avatar
Rock Currier March 28, 2008 11:35AM
There are a number of ways to clean copper. If the quality of your specimens is high, nice crystals for example, you may want to consider eliminating some of the methods. If your specimens are in the tourist rock range, you can get pretty aggressive in cleaning them. Another consideration would be what minerals are associated with our specimens. Most fine copper specimens you may not want to clean all that much, or not at all. Another factor in cleaning copper is how much you know about chemicals and how to handle them. If you can post a picture of the specimen(s) you want to clean and give some indication of how much you know about chemical reagents, we may be able to advise you better.
Rock
avatar
John Kupar August 10, 2008 06:25PM
We just returned from the UP of Michigan with some great uncleaned copper samples. A few may be half breeds (Copper & Silver). What is the best way to clean these samples?

Best Regards,

John
avatar
Łukasz Kruszewski August 10, 2008 07:05PM
Hi! I've heard about a method using potassium tartrate + NaOH + H2O, but I don't remember the portions now /: I'll write when I find these informations.

Good luck!
avatar
John Kupar August 10, 2008 09:16PM
I look forward to receiving the formula. Have you tried the vinegar/water solution mentioned above? We visited three old mines in the UP of Michigan and found several excellant examples in the tailings. Even found a hand drill from the 1850's!

Thanks!

John
avatar
Paul Brandes August 10, 2008 10:45PM
John,

Please read my earlier posts (CaptPaul) to get a start on cleaning your UP coppers.

You must have been there for the Mineral Retreat?? What 3 mines did you visit??
avatar
jeff melanson August 11, 2008 12:21AM
hi there try ketchup, we us it to clean all or cape d or copper it works great
avatar
Costas Constantinides August 11, 2008 01:16AM
Hello,,The trick with cleaning and keeping native copper tarnish free is what you do when you have completed the acid process.
This is what I do and it works well on small pieces but when specimens are large and very dendritic it's just good.
The idea is to get the acid and water off and dry as fast as you can.
1..remove specimen from acid and rinse in water
2..now rinse specimen in a container of warm water thoroughly
3.rinse the specimen in metholated spirits.This enables the remaining water to mix with the metho and when removed to dry does so quickly.
4.lightly coat the specimen with your choice of copper type varnishes
I'm not fond of doing this as most native coppers are best preserved as they are
Costas
avatar
Keith Compton December 07, 2008 02:26AM
Kyle

Sorry I didn't see your message earlier.
I don't like to clean any "green" off native copper - whether natural oxidisation or any of the many copper mineral coatings.
However, given your question here are two tips:

(i) I don't think you can get TarnX in Australian but you can use Goddards Silver Dip - you can generally pick this up in the cleaning sections of Coles or Woolies or any hardware store. You could also look at some of the car wheel cleaners - some of these have similar principal chemicals.
(ii) Rather than use a copper varnish you could consider hair spray - much easier to apply and more importantly, to remove.
Cheers
avatar
Franklin Roberts January 11, 2009 08:34AM
One method that I experimented with a few years ago seemed to work miracles with corroded copper. It was a variation on the "cyanide bomb" process that the plating industry used all too often, that is until the industry realized just how insanely dangerous the process was and how efficient the legal system was becoming.

The original process involved placing the copper piece to be cleaned into a bath of saturated sodium cyanide solution, adding a slug of 30% hydrogen peroxide to the container in one portion and then running like hell. Within a few seconds, the mixture would flash to steam, ejecting a cloud of boiling hot water, cyanide solution, steam, oxygen and a cloud of deadly hydrogen cyanide gas into the air and all over the immediate surroundings. For the life of me, I cannot imagine a more foolhardy way to clean and polish metal. For somebody to take such a stupid risk, there had to be some sort of payoff at the end.

There was. Not only did the the process instantly remove hard, pitted corrosion, it actually imparted a mirror-bright polish to the workpiece. I can only assume that it did so by first reducing the oxide coating and then removing a layer of copper a few atoms thick. I've seen the results of the cyanide bomb technique and it looked as if somebody had invested several hours of elbow grease instead of a few seconds time (and half a lung).

I had read somewhere that thiourea, the main ingredient in Tarn-X, was finding many new industrial uses, mostly replacing cyanide in some metallurgical processes such as leaching and plating. I had access to a lab and the proper chemicals at the time, so I attempted to duplicate the cyanide bomb process by simply substituting thiourea for sodium cyanide. I was pleased to discover that the experiment worked perfectly on the first attempt. While it was still a violent exothermic reaction and very messy, at least there was no cyanide to clean up. Even so, this reaction is an "outdoors only" experiment.

The process imparted a beautiful mirror shine to several non-ferrous metals that I bombed, even to stainless steel.

Frank
avatar
Anton Ivanov January 11, 2009 11:25AM
HF - Hydrofluoric acid , but be verry, verry careful: Hydrofluoric acid is extemely corrosive and a contact poison.
regards
Anton
avatar
andrew October 13, 2010 08:33AM
clean with hydrocloric, brighten with vin and salt, then coat it immediatly, and dont play with cyanide!! unless ur a nut case like the previous comment
avatar
Reiner Mielke October 13, 2010 12:58PM
The problem with cleaning copper is in keeping it clean. Some treatment methods such as with HCl seem to not stay clean as long as others. It seems that some methods activate the surface making them more susceptable to tarnishing. At best all cleaning methods are temporary unless you coat the sample with something afterward ( like lacquer). I haven't tried this, but if the sample has no matrix, heating it and coating it with a thin layer of wax might work better than lacquer and is easier to remove if you need to.
The results also depend on the impurities in the copper, some Michigan copper will not clean at all. The best thing I have found to clean copper (in that it stays cleaner longer afterward) is using citric acid. However even then you can expect it to tarnish brown in a couple years if not sealed with something.
avatar
Peter Haas October 22, 2010 05:38PM
Thiourea, as the name says, contains sulphur, and this is easily set free as sulphide in an aqueous solution. Sulphide, in turn, will attack copper over time (due to the extremely low solubility products of copper sulphides).

Also note that thiourea is an extremely strong mutagen that should be handled with as much care as possible ! Denaturing proteins with thiourea is easy as pie. Don't let the name fool you - the relation to urea is only a structural one, its properties are quite different.
avatar
Bill Boehm January 10, 2012 06:11AM
First time user. I have some native copper that I have been trying to clean with muratic acid. I put several pieces in a gallon ice cream bucket, cover them with full strength acid overnight. Next I put them in a 5 gallon bucket of cold water and rinse them. Then I take them out one by one and scrub them with a toothbrush, rinse them off, towel dry, and put them in front of a heat lamp to dry with the intention of spraying them with hair spray or a lacquer. Before I can get them sprayed, the copper tarnishes, and the rock? material turns whitish/greenish/bluish. I tried soaking them in vinegar and coca-cola to brighten them up but to no avail. I put them in Tarn-x and it would make the copper a ....copper.....color, not shiny bright, but then by the time I rinse them off towel dry them to spray them they are tarnished again. I have then with some pieces resoaked them in muratic acid a second time but the second time they don't even bubble or steam. Some of the pieces are solid copper and some are copper imbedded in red rock, creme colored rock, green rock, black bubbly rock. I am getting frustrated at not being able to get any copper to stay shiny long enough to spray coat. When I tried soaking the specimens in cold water mixed with baking soda, the rocks came out looking kind of pinkish with a kind of slimy coating on them. Are there time limits for soaking the specimens in the muratic acid? Baking soda solution? (What ratio) How many rinses? Cold water? Warm water? Outside temperature make a difference? Time limit in Vinegar? Vinegar and salt? (Ratio) Coca-cola? Tarn-x? Copper Brite? Super iron out? Brasso? What is the proper sequence for doing these methods and the right length of time. I have been trying to do anywhere from 25-50 pieces at a time. Is that too many? I am 73 years old, retired and have a full schedule from spring to fall, so I try to get this done in the winter. By the first of March I will be heading to Arizona to get some more goodies so I have to work fast in the winter. I would appreciate any and all information and help I can get concerning this subject. Thank you. Bill
avatar
Rock Currier January 10, 2012 09:42AM
Can you show us a picture. Some of the guys who clean a lot of this stuff use an acid dichromate solution to make them really bright and shiny for the tourists. Collectors generally don't like real acid brightened copper specimens.

Rock Currier
Crystals not pistols.
avatar
Paul Brandes January 10, 2012 01:47PM
Bill,
First off; welcome to Mindat!!

Now as far as cleaning your copper, I see two mistakes immediately. First, never leave the copper in muriatic acid overnight! This will “burn” the copper and destroy any crystals you have. I usually only leave any specimens in for 5 minutes at the very longest, and then only if there are no crystals on it (I do not use muriatic or any strong acid on crystalised specimens). Second, you are trying to do your cleaning in mass (25-50 pieces at a time); this is way too many at once. What is more than likely happening is you are putting so many pieces in that you are diluting the acid which changes the chemical makeup of the solution and will result in funky coloured pieces of copper. I will only do one or two at a time and if there is a lot of material to be removed, I will not re-use the acid, but rather start another round with fresh acid. And then there are just some pieces of copper, especially the higher arsenic content coppers from the Keweenaw Peninsula of Michigan, that you will have a hard time cleaning. It can be done, but with acids I don’t recommend using. Many of the folks in the Keweenaw will use a combination of acids and other chemicals to clean copper, and then as a final step, use Copper Brite (the acid dichromate solution Rock mentioned) to preserve the finish. But as Rock also mentioned; most serious collectors of native copper leave their specimens in a “natural” state with the patina intact.

If you just want to clean your copper, I would recommend placing them (2 or 3 at a time) in muriatic for no more than 5 minutes, then rinsing them off with water (a small pressure washer works well for this), drying them (I generally use a heat gun or hair dryer), then dipping them in Copper Brite. If you have crystalised specimens, I would leave them alone as most acids will ruin the sharp crystal edges by rounding them off...
avatar
Scott Sadlocha January 10, 2012 05:11PM
I have quite a bit of copper and I am still trying to figure out a decent way to clean it. I tried a few small pieces in Tarn-X. They came out shiny, but turned iridescent in a matter of hours. A second soak resulted in quite a bit less iridescence. That was just a test, but it held promise for a resulting shiny piece with distinct edges. I have tried dilute HCl, but did not like the results at all. Any edges were rounded (as Paul mentioned) and the entire piece took on a hackly, shimmery appearance. With that test I ruined an interesting piece from the Phoenix Mine.

My problem is that I don't like the shiny "new" copper appearance. My favorite coppers are those that have the brownish patina to them, almost as if they had been kept in someone's pocket for a few decades. I have a decent amount of specimens like that, I am not willing to soak them in anything. Still, quite a few of them would exhibit more crystallization if I could find some way to clean them better. In some cases, the copper disappears into fractured calcite, or into matrix rock, but I can tell that there is more crystallization evident based on a few exposed surfaces.

I have tried mechanical cleaning, using small picks and a water gun. This does work in many cases, but it seems to take forever. On some pieces, it seems like it will take me 20-30 runs with this method to clean things out. The worst cases are those with copper and distinct calcite crystals, with matrix I want to remove. The copper is durable for the water gun, but I have to really be careful near the calcite.

When I get home, I will try to post a photo of what I am talking about. One piece that I have found particularly vexing falls into this category, and the piece almost seems to be wrapped with a granular matrix. I talked to some of the guys from the Caledonia mine at the last Detroit show about this piece, and they suggested continuing with the mechanical method. I think a lot of the pieces I have are just going to have to wait until I have a heck of a lot of time to work them over. I do have one piece at home that I really like, but I am not sure how it was cleaned. It does have a bit of a "new" look to it, but it is not overly shiny. More of a matte finish, and the crystallization is fantastic, though it is just a TN. Unfortunately, I can't find out how it was cleaned, as I found it at an estate sale quite a while back, and the original owner was not available.
avatar
Bill Boehm January 10, 2012 07:07PM
Mr. Rock Currier: I/my wife will get some pictures posted for you to see. Thank you very much for the prompt reply to my post. Bill
avatar
Michael Hatskel January 10, 2012 07:12PM
Reports of copper dissolving in dilute HCl are puzzling to me since I first saw it in the book by Sinkankas.
It is not supposed to be happening, is it?
Dilute non-oxidizing acids, like HCl, at room temperature shall dissolve the surface coatings (oxide, sulfide) on copper but not the metal itself. Unless there is a sizable amount of a more electro-positive impurity (Ag, for example) that helps copper to corrode. But that is less likely to happen in the well-formed copper crystals.

Does someone have an explanation of the observed copper dissolution? What am I missing here?



Edited 2 time(s). Last edit at 01/10/2012 07:37PM by Michael Hatskel.
avatar
Joseph Polityka January 10, 2012 09:14PM
Hi,

You can try this method I was taught years ago by my high school science teacher. He showed me this cleaning technique on a copper penny which you might want to try first.

Place the tarnished penny in a suitable glass container. Cover the penny with white vinegar. Drop a small quantity of ordinary table salt into the vinegar and watch the penny magicallly turn bright and clean. Safely dispose of the solution and start again on one of your small copper specimens.

Let me know what happens, please.

Good luck,

Joe
avatar
Bill Boehm January 11, 2012 03:44AM
Rock Currier, Paul, Joe: Thank you very much for responding. I was going to take the photos today but the camera needed new batteries. I promise I will post the pictures tomorrow. Is there a limit on the number of pictures I can post? A size limit? My wife will have to upload/download? the pictures as I am not an intellectual when it comes to computers. Bill
avatar
Rock Currier January 11, 2012 09:11AM
When cleaning copper, collectors are usually concerned with degrees of brightness and the tone or shade of the patina they think is ideal. These are caused by slight changes in the surface chemistry of the copper, and I know of no real way to achieve a particular degree of brightness of oxidation other than trial and error. I also think that to some extent it all depends on the purity and amount of other elements mixed in to the copper from different localities. I think you will find that trial and error will be the only way to get the exact degree of tarnish you desire.

Rock Currier
Crystals not pistols.
avatar
Scott Sadlocha January 12, 2012 03:22AM
Okay, I didn't get a chance to post the photos yesterday, but I am getting around to it today. Unfortunately, I can't find the "particularly vexing" piece I referenced. I just realized it is in my camper, and I don't feel like going out there to search for it. While I am finishing my basement, especially my office and desk area, I have moved a bunch of items out there to store them including a few specimens I need to clean. Still, I have gathered a few others to post up, and I will try to get the other one tomorrow, or over the weekend.

This first one is the small TN I was referring to. It is about 3cm x 2cm, and has a bit of an iridescent sheen to it, and I believe it was chemically cleaned. Still, the crystals are pretty sharp, so however it was cleaned was a decent job. I am not very fond of the finish of the piece, but otherwise I really like it. The branching nature of the piece, along with the crystallization (and what I believe might be twinning) make this one of my favorite coppers.





open | download - Copper Specimens_001.JPG (61.5 KB)
open | download - Copper Specimens_002.JPG (63.9 KB)
open | download - Copper Specimens_003.JPG (62.8 KB)
avatar
Bill Boehm January 12, 2012 03:36AM
Rock currier, Paul and Joe here are the photos. Bill
open | download - 006.JPG (399.1 KB)
avatar
Bill Boehm January 12, 2012 03:39AM
Rock currier Paul and Joe here are the photos. Bill
open | download - 009.JPG (397.7 KB)
avatar
Scott Sadlocha January 12, 2012 03:40AM
By the way, that first piece is a Phoenix Mine specimen, for anyone interested.

This second one is a bit larger, but is an example of a piece I would like to clean a bit, but not change. It is about 25cm x 13cm, and I was told it came from "York Mine" or "New York Mine". Since I can't match that up exactly with an existing mine and there are several mines and prospects that reference New York and various parts of it (Brooklyn), I can only be sure it comes from Copper Country. This piece is an example of one that I would like to keep relatively intact. I really like the red and green patina to it, but would like to clean the gray material out of all the nooks and crannies. This is one that is taking some mechanical cleaning to get it looking better. Besides the green and red staining, there are some spots of light blue on it, though I am not sure what it is (the color is not right for chrysocolla or something along those lines) and there are some micro pockets of epidote on the bottom. This piece is an example of quite a few I have--where most of the dirt is gone, but there is some tough, hard material stuck in small pockets.



open | download - Copper Specimens_004.JPG (101.2 KB)
open | download - Copper Specimens_006.JPG (101.3 KB)
avatar
Scott Sadlocha January 12, 2012 03:46AM
This last one is a partial copper crystal on matrix with copper throughout, about 5cm x 4cm, and is a bit more along the lines of the finish that I like. I have a few other pieces like this, but this is the only one that was handy at the moment. There is not much I would do here except perhaps a bit with the water gun on a lower setting.

I just noticed that Bill is posting as well. A lot of what he has is similar to material that I have, where quite a bit more cleaning is needed. On some of the pieces, you can tell there is copper crystallization, but it is hard to see with all the matrix making it look like a lump.

*This last piece is from the Indiana Mine.









Edited 1 time(s). Last edit at 01/12/2012 03:47AM by Scott Sadlocha.
open | download - Copper Specimens_007.JPG (60.7 KB)
open | download - Copper Specimens_008.JPG (65.6 KB)
open | download - Copper Specimens_009.JPG (78.7 KB)
avatar
Bill Boehm January 12, 2012 04:02AM
Rock currier Paul and Joe here are some photos. Bill
open | download - 001.JPG (397.2 KB)
open | download - 002.JPG (412.6 KB)
open | download - 003.JPG (388.5 KB)
avatar
Bill Boehm January 12, 2012 04:05AM
More photos from Bill





Edited 1 time(s). Last edit at 01/15/2012 05:10AM by Rock Currier.
open | download - 004.JPG (405.5 KB)
open | download - 005.JPG (387.7 KB)
open | download - 007.JPG (407.8 KB)
avatar
Bill Boehm January 12, 2012 04:09AM
More rocks from Bill







Edited 1 time(s). Last edit at 01/15/2012 05:11AM by Rock Currier.
open | download - 008.JPG (401.2 KB)
open | download - 010.JPG (384.7 KB)
avatar
Paul Brandes January 12, 2012 09:44PM
Scott,
Did you collect the Phoenix specimen yourself? Reason I’m asking is are you sure that’s a Phoenix specimen? To me, it looks a lot like the Laker Pocket coppers that came out in 2008 which would have a brick red patina naturally. Your Indiana crystal is typical of what comes from there; partial/modified crystals with a tenorite coating.

The “York” piece and all of yours Bill are more in line of what comes out of the piles these days. One thing I failed to mention before is for the hard to reach spots, a can of Dow Scrubbing Bubbles does a pretty good job of loosening up the gunk without damaging anything, then water gun or pressure washer clean it the rest of the way. I’ve had pretty good success with this method. Another item that works quite well are the small spring loaded centre punches you can buy at Harbor Freight or Northern Tool. A few repeated pops usually will loosen the rock to a point you can chip it off fairly easily. Just be careful you don’t hit the copper as it will damage it quite quickly. As far as acids, muriatic is probably the safest and best “stronger” acid to use.

Bill, do you have any idea where your coppers are from (what mine)?? It would appear that a couple of those, especially the one in photo 010, are somewhat crystalised so you might want to be a little careful with those; the rest I would dip in muriatic for a couple minutes, remove, rinse, and repeat until you get the desired look. Some of those look like they will clean up nice with a little patience; others, I wouldn’t hold my breath on…..
avatar
Rock Currier January 13, 2012 08:37AM
Bill,
I don't think you are going to find any chemical that is going to make all those specimens look really good. A little hydrochloric acid will remove any calcite that is on the specimens, but it will also probably remove any tarnish or oxidation that you may find attractive on the specimens. Then what you will most likely be left with are silicates like quartz, epidote and rock. The only way to effectively remove those would be through the use of Hydrofluoric acid and I am not sure I see any specimen in your group photos what would be worth the danger and expense of using that reagent. Even then about the best you could hope for is to strip the specimens down to the bare copper and have it really bright. Of course with time the color will tone down and oxidize. But of course there is no guarantee that they will oxidize to the color and or tone of your taste. You can experiment with fresh bright copper in a variety of ways like holding it over a flame and you may hit upon a method that will oxidize it just the way you want, but I won't be able to advise you there.

Rock Currier
Crystals not pistols.
avatar
Bill Boehm January 13, 2012 03:21PM
Rock Currier, Paul, Scott: Scott, what do I have to do to get my photos to come up like yours instead of "open-download" like mine turned out? Rock Currier, what is epidote and what does it look like? Paul, my wife and I bought a metal detector and spent three weeks in the upper pensinsula of Michigan going over old mine rubble???? - tailings???? in a learning process. We had a great time doing it and loved the beautiful scenery. I know Mandan mine, Phoenix mine, Central mine, Cliff mine, and anywhere else we saw piles of rocks while we were out driving the back roads. We even found lots of old bottles, some with the cork tops. We plan on going back up there again this year. We are not just interested in finding copper, we love exploring any and all rocks. Some of our friends and family laugh and say we have rocks in our heads, but we love it, we're retired, and its good exercise and good time together..
avatar
D Mike Reinke January 13, 2012 03:56PM
Bill,

Ain't it great?! And the more you learn, the more enjoyable it gets. The crust of the earth is amazing...deep, in more ways than one. Having your wife share the interest is the best. I love my rock collection, but it can't love me back, can't even get coffee...
Type 'epidote' into mindat, you'll see plenty in the gallery. keep you occupied this winter.
Have you tried sandblasting a copper piece? I had an acid damaged galena that was expendable, it looked better sand blasted (w/o my glasses on). It is too soft, it looks pocky upon closer inspection but it took the crud off. Copper would fare better.

Take care,
Mike
avatar
Rock Currier January 13, 2012 09:25PM
Bill,
Can you be more specific about the photos you are talking about? Epidote is a green to black mineral often found associated with copper specimens from Michigan.

Rock Currier
Crystals not pistols.
avatar
Paul Brandes January 14, 2012 01:56AM
Sounds like you had a great time in "da UP" this summer, Bill. I also recognise all the mine names you mentioned as they are sites I am very familiar with. However, this thread is devoted to cleaning native copper, so I would suggest that if you want to continue talking about UP copper, geology, or its scenic beauty, maybe a Talk Page would be more appropriate.

Just a suggestion...
avatar
Bill Boehm January 14, 2012 06:30PM
Mike - Rock Currier - Paul: Mike, I may try some sandblasting later on if I can come up with some extra bucks to get a unit. Mr. Rock: I was talking about I liked the way we all can see Scott's photos just by scrolling down. My photos had to be clicked on to open. Paul:..Sorry, I wasn't aware that there were limitations on what could and could not be discussed here. I need to get better accquainted with this website and what is available. I do apologize. Thank you very much to all of you that respond. I excitedly look forward to corresponding with you all. I will later on try to navigate to a "Talk Forum page" so I can ...BS..a little. I will however be back here too. Bill
avatar
Scott Sadlocha January 14, 2012 10:32PM
Sorry, haven't been by my computer much in the past few days.

Bill, you can add a photo in your post once you attach the file. There will be a button that title "Create Link in Message" once the file is attached to the message. What I usually do is type up what I want to add to a post, add the files, and then put my cursor down below my text a couple lines. I then click on the button to add the photo to the post (you won't actually see the photo until the post is made, but there will be a text line), drop down a couple lines, and do it again, repeating for all the photos.

Paul, I did not collect the Phoenix piece myself, so I am not entirely certain. I got it from the estate sale of a collector, and that is the information I was given at the time. I would much rather it be a Laker pocket piece of course, but really couldn't say, and I am not sure how that could be determined. Either way, I like the piece a lot, and even though it is small, it is one of my favorite coppers out of the many I have. There is just something about it that really appeals to me.
avatar
Paul Brandes January 15, 2012 12:49AM
If that is the information you were given Scott, then by all means go with it. If it came from an estate sale, more than likely it is from Phoenix as the Laker Pocket material is quite new on the market.

It's not my decision Bill what can be discussed on here, that's for the managers. It was more of a suggestion that if you wanted to chat about other things besides how to clean copper to start a locality talk page on the Copper Country, and there you could really have a grand discussion about all things Keweenaw. grinning smiley

Earlier you were asking about epidote; here is an example from the Centennial No. 2 Shaft in Houghton Co.
avatar
Bart Cannon January 15, 2012 04:18AM
I think that thet the dull gray to black patina on native copper and native silver might actually be copper and silver sulfides.

Copper and silver are sulfur getters. They draw sulfur out of the air.

I wonder is a quick flash in diulte nitric acid might produce a tolerable and not overly bright finish.

I've used "Linde A" polishing compound applied and rubbed with a stiff artist brush to produce a "natural" looking clean-up on both native copper and native silver.
avatar
Scott Sadlocha January 15, 2012 05:37AM
Some of the cleaning methods got me thinking about a reverse process. Since I dont like really shiny clean pieces, I was wondering if there was a method to speed up the tarnishing or oxidation process on a piece that has been recently cleaned. Perhaps some way to make it look old a bit quicker.
avatar
Jim Gawura January 15, 2012 07:54AM
Scott,
I've noticed that some copper when being rinsed in water to wash off any remaining acid will oxidize if left in the water for a day or more. It appears that whether or not the oxidation is fast, slow, or non existent depends on the chemical makeup of the copper. I've had specimens that had to be taken out of the rinse and either blown or sun dried immediately or they would oxidize. Others could soak for days and still come out bright! Same in the cabinet, some of the copper is fairly oxidized after only in a few months and other pieces have been in the cabinet for years and are still shiny. Also had both results from the same mine. I use sulfamic acid exclusively for any acid cleaning. Natural and just washed and scrubbed or pressure wash is my preferred cleaning method. Unfortunately it seems that the majority of the specimens I collect have some kind of nasty coating that usually has some calcite next to the copper. Acid works fine. My experience has been that HCL no matter how dilute and how short a duration the soak it etches copper crystals and rounds off all the sharp edges of the crystals. Sulfamic undoubtedly etches the copper, but at a rate so slow I can not discern any damage. Sulfamic acids main use is for cleaning out boilers. Usually comes as a white powder in 50lb. bags.
Good Luck,
Jim
avatar
Bill Boehm January 15, 2012 03:05PM
I have a big pressure washer I use for cleaning the skidloader, tractor, etc. Is this what you fellows are talking about using on cleaning copper, or is it some small unit for crafts and hobbies? Thank you. Bill
avatar
Scott Sadlocha January 15, 2012 07:02PM
Bill, it is a little handheld unit that directs a thin stream of high pressure water to the piece. It has worked wonders for me in cleaning so many specimens of so many minerals that I don't know what I would have done without it. You do have to be careful with certain minerals low on the hardness scale, but you can adjust the spray quite a bit. I believe the units were originally developed for the garment industry, but that have proved quite beneficial to mineral collectors everywhere.

I can't sing the virtues of this cleaning enough. I have more than a handful of specimens that elicited "Oh my gosh!" moments after I gave them a go with the water gun, including one especially funky Siderite with Pyrite from Eagle Mine. It is really great for copper because you don't have to worry much about being too careful, unless there are accessory minerals. Quite a few people and dealers sell them, and you should be able to find them fairly easily. I bought mine for about $80 a few years ago, and it has performed flawlessly since.
avatar
Bill Boehm January 16, 2012 02:27AM
Scott: Thank you for answering my question about the pressure washer. I'll see if I can come up with one. Bill
avatar
D Mike Reinke January 16, 2012 02:54AM
Bill,
Scott's idea is probably better than sand blasting, but ran into a guy who was strapped financially, but had some ingenuity; He took stuff he found, larger pieces anyway, down to the carwash, secured them some way, then used that power wand on 'em! i got a kick out of that. A country boy can survive I guess...

Mike
avatar
Bill Boehm January 16, 2012 06:22PM
I could do that with the big pressure washer I've got except that right now the ground is covered with snow and ice. I think I'll try to find one of those small pressure washers. Bill
avatar
Scott Sadlocha January 16, 2012 06:42PM
Okay, the weather was a bit nicer, so I went out to the camper and grabbed the other pieces I had referred to that I kept stored out there. I am going to create a handful of replies to get the information up and post the photos. The first few sets are of the larger piece I had previously mentioned. This is the one that is primarily copper, with a wrapping of matrix material. Looking at it, the piece almost seems like the remnants of an infilled vesicle, with part of the "rind" of the vesicle attached.

On this piece, I can see some decent copper crystallization peeking out, as well as a few decent crystals already exposed. The first shot is of the whole piece, what I would consider the front, and the second is a closeup. Subsequent posts will show other angles and more of the matrix. As you can see on these shots, there is some calcite attached. While the periphery calcite is damaged, there are some very nice smaller crystals in the center, and I would rather not damage these. I am not sure if it can be seen, but there are a few areas with a coating of micro-crystalline quartz as well. This entire piece is about 10cm x 10cm.



open | download - Copper Specimens_010.JPG (104.8 KB)
open | download - Copper Specimens_011.JPG (169.4 KB)
avatar
Scott Sadlocha January 16, 2012 06:49PM
The pictures came out a bit overexposed, because I had some extra lighting on it to try to illuminate all the nooks and crannies. Offhand, I can't recall where this piece was found, but I have it written down on a master list in the larger box I had the pieces in, just forgot to grab that.

This second set of photos shows how the matrix material wraps around the copper. It is almost like the copper was encased in it (and it most likely was if my assumption is correct). At points where they meet, there is actually a small gap which I think I may be able to exploit to separate them. There is some layering extending outward, including a thin layer of pistachio green epidote where the matrix meets the copper. This matrix is very porous and somewhat crumbly, and peppered with very tiny crystals of various accessory minerals, especially in the larger bubble remnants. Based on the porosity of it, I thought it would break off a bit easier than it has. Still, with several goes from the water gun, I have been able to whittle away at it.





open | download - Copper Specimens_012.JPG (113.8 KB)
open | download - Copper Specimens_013.JPG (145.4 KB)
open | download - Copper Specimens_014.JPG (141.3 KB)
avatar
Scott Sadlocha January 16, 2012 06:52PM
This third set, from the same piece, shows various angles. The first photo shows a bit of a closeup of the porous matrix, on what I would consider the back/bottom of the piece. The second photo shows the layering and the epidote at the join. With the third photo, I tried to capture a small pocket on the lower right center of the piece. This didn't come out as good as I'd hoped, but it is still visible. There is some interesting crystallization in this pocket.





open | download - Copper Specimens_015.JPG (195.5 KB)
open | download - Copper Specimens_016.JPG (166 KB)
open | download - Copper Specimens_017.JPG (137.5 KB)
avatar
Scott Sadlocha January 16, 2012 06:58PM
These shots are from another piece, I believe from the same location as the piece I just posted. This one is a bit smaller, and definitely does not have as much potential, but it is a bit interesting to me. It is about 10cm x 5cm and again, I can see some crystallization poking out. However, on this piece, the matrix seems to be layered in with the copper, and has been very difficult to remove. Not to mention, the rock material is much harder, and it is difficult to tell when the rock ends and the copper begins. I doubt the matrix material would be affected by a chemical dip. I have been going at this one with the water gun as well, but the results haven't been much different than the original piece. I do like the coloration the accessory minerals have provided. On the last photo, you can see where the water gun has torn apart a calcite pocket. It was heavily damaged already, so I did not regard it as something to work around.





open | download - Copper Specimens_018.JPG (101.5 KB)
open | download - Copper Specimens_019.JPG (129.7 KB)
open | download - Copper Specimens_020.JPG (94.1 KB)
avatar
Scott Sadlocha January 16, 2012 07:03PM
This next series of photos details the Phoenix piece I tried to chemically clean. It is a branching piece that was almost completely covered with a thin layer of calcite. It spent a few minutes in a bath of dilute HCl and came out looking like this. It was my first experience using copper with HCl and I was extremely disappointed, to say the least. As you can see, it looks fried, and any decent crystallization is gone.





open | download - Copper Specimens_021.JPG (77.1 KB)
open | download - Copper Specimens_022.JPG (74.4 KB)
open | download - Copper Specimens_023.JPG (97.2 KB)
avatar
Scott Sadlocha January 16, 2012 07:06PM
Finally, two sets from pieces I gave a bath in Tarn-X. With this method, they edges were kept distinct, and the whole process took much longer. However, shortly after being removed and rinsed, they took on a crazy iridescent sheen. I tried a second time, and ended up with less of the iridescence, but it is still there. The thing is, this sheen doesn't show up right away, but rather a few hours after. I think if I do something to dry them off and perhaps coat them, it won't be so prevalent. Still, they end up with a bright patina that I am not really fond of.

Again, I don't have in front of me the location. These are both smaller pieces, like the Phoenix piece.





open | download - Copper Specimens_024.JPG (119 KB)
open | download - Copper Specimens_025.JPG (140.8 KB)
open | download - Copper Specimens_026.JPG (170.5 KB)
avatar
Scott Sadlocha January 16, 2012 07:07PM
The last piece, another Tarn-X job.





open | download - Copper Specimens_027.JPG (86.6 KB)
open | download - Copper Specimens_028.JPG (108.5 KB)
open | download - Copper Specimens_029.JPG (83.2 KB)
avatar
Bart Cannon January 16, 2012 11:21PM
I don't think that this cleaning method has been mentioned.

When we came across Keeweenaw coppers that were enclosed in basalt, we would heat them up in the oven at highest heat, and them drop them into a bucket of cold water. Many treatments were necessary, but with luck, most of the basalt would fall away. No acid, No neutralization needed.

It was thus possible to convert a worthless specimen into a five dollar specimen via ten dollars of effort.

Bart
avatar
Dan Fountain January 16, 2012 11:56PM
Bart,

I like your idea a lot. Sometimes we'd find that just using a hammer to shatter the basalt was the only effective means, but the thermal method seems a lot more elegant - plus you get to heat things up way beyond safe limits & throw them in water! R-R-R! More power!
avatar
Paul Brandes January 17, 2012 02:52AM
Bart Cannon Wrote:
-------------------------------------------------------
> I don't think that this cleaning method has been
> mentioned.
>

Actually, it has been mentioned in many books and research papers over the years. This was the method used over 5,000 years ago by the ancient miners of the Copper Country who wanted to separate copper from basalt. It is said that they would build a large bondfire along a stream or lake and toss copper into it to heat it up. Once hot, they would throw ice cold water on them and supposedly, the contraction of the copper would shatter the rock, sometimes with explosives results. I am told that it does work, although it's not the most effective way to remove basalt from copper.
avatar
Bart Cannon January 17, 2012 06:54AM
Paul,

I'm on the edge of my chair. What IS the best method to remove basalt from Michigan coppers ?

One method I've thought about is known as the "electromagnetic pulse pulverizer". I worked with a guy who was developing it to liberate diamonds from kimberlite. He was able to liberate orthojoaquinite crystals in fine grained syenite for me from a rare earth deposit in Alaska.

He went on to different dreams, and told me how to build the device. It required high voltage capacitors the size of oil drums and a the switch was driven by a bullet. More hazardous than the bucket steam bomb I once employed on coppers.

I have done much research on ancient indian mining in the Keeweenaw. I even worked with Dr. Rapp on the trace element chemistry via WDS on Michigan coppers with the hope that we could establish trade routes and copper sources for copper artifacts in North America. I had crazier hopes. I wanted to verify Pre-Columbian trade contact between Europe and the Keeweenaw people.

We determined that trace chemistry was hopeless via WDS, and even hopeless via mass spectroscopy because the chemistry of Michigan coppers changes by the foot in the mine. My final conclusion was to use silicate inclusions as fingerprints, but no European museum would allow messing with their artifacts.

Much the same with another of my projects. Determining the provenance of the spear point in Kennewick Man's ilium. Curators mostly just want to keep stuff pristine in their museum drawers. When I was examining K-Man's ilium in the Burke Museum with my Optivisor, hands behind my back, I got tapped on the shoulder and told "you are too close".
avatar
Bill Boehm January 17, 2012 12:55PM
Bart: What was the temperature setting on your oven, and how long did you leave them in there before putting them in the water? You're talking about copper with just certain kinds of rock? Since I have no idea what you were talking about with those 50 cent words in your last post and I don't know what the difference is between a green, brown, black rock/matrix??? Can it be dangerous to put some rocks in the oven? Not a rocket scientist...........SCOTT:.....How long did you leave the copper in the Tarn-x? Did you rinse them in plain water or water with baking soda? Vinegar and Salt? ......Thanks guys....Bill
avatar
Paul Brandes January 18, 2012 01:46AM
Bart Cannon Wrote:
-------------------------------------------------------
> Paul,
>
> I'm on the edge of my chair. What IS the best
> method to remove basalt from Michigan coppers ?
>

Unfortunitely, one of the best ways to remove basalt is also one of the most dangerous; that's to use HF, which I do not recommend anyone using!! As I mentioned before, one of the spring loaded centre punches works well, as does just carefully chipping away at the basalt. I know that can be time consuming, but at least you'll live to see tomorrow.

Bill, I believe what Bart is talking about are the different coloured basalt matrix one can find attached to the coppers of the Keweenaw. They are actually quite easy to distinguish; green is epidotised basalt. Black is the common colour for basalt. A chocolate brown/reddish coloured basalt is where the majority of the "good" minerals were found during the mining days. The Pewabic Lode in Quincy and other mines nearby was this reddish/brown colour and it was a sign to the miners that they were in potentially good ground.
avatar
Bill Boehm January 18, 2012 03:40AM
Mr. Paul: Once again I must thank you for making things a little bit easier for me to understand. I do apprreciate that. Bill
avatar
D Mike Reinke January 18, 2012 05:23AM
Bill'
Bart has not answered, and I've never tried it, but I'll keep it for future reference, certainly. My, and I guess most ,ovens hit 550 degrees. That wont melt copper or basalt, so crank it...How long, don't know, but I bake bread for 50 minutes, and I would suspect a rock if small, would be pretty hot in 50 minutes, or less, of course, depends on the rock... And certainly, drop in water ASAP, I'd guess, or you lose heat. Winter would be a good time to do that, heat your house. Summer's hot enuf w/o that...

Mike
avatar
Jim Gawura January 18, 2012 06:04AM
Scott,
Your Phoenix specimen looks like most of the pitting and rough surface may be do more to 150+ years of oxidation on the pile then the acid. To long in the hcl will give the specimen a melted look. If the piece wasn't totally enclosed by calcite it's probably oxidation. A lot of Keweenaw copper has a thin layer of calcite around it and etching away the calcite will leave that small gap that can be exploited in removing the matrix. Unfortunately with some specimens it's almost as if the matrix is part of the top layer of copper. Specimens from the Seneca #1 have been the most frustrating to clean for me. You might reduce or eliminate the iridescence on the acid cleaned copper by quickly drying it once out of the final rinse. My results have been mixed. Some copper appears more susceptible, but a quick blow off and follow up with a heat gun, from prior incidents don't let your wife catch you with her hair dryer, or placed in direct sunlight on a warn day seen to help. Tarn-X is made by Jelmar in Skokie Illinois. The MSDS shows it it contains Sulfamic Acid and Thiourea, but the mixture is listed as proprietary. If your interested in obtaining Sulfamic Acid or some other tips PM me. Spent 30 years collecting in the Keweenaw.
Cheers,
Jim
avatar
Bart Cannon January 18, 2012 07:15AM
Mike,

My copper baking was done in 1963 and 1964. I was 13 years old. The oven was also about the same age. I don't remember paying any attention to the operating conditions, but I suspect 300 degrees would be enough to get the rock hot enough for thermal shock and plenty of differential expansion of dissimilar materials.

At 50 cents per 50 cent word, I think you now owe me $2.00.

As for HF, I would be dis-inclined mostly because of the expense of the HF versus the value of the copper specimen.

In previous decades I frequently used HF and only suffered one wound. Somehow a drop found its way to my cuticle and a day later that area felt like a bruise. One tip about HF is that you should never use rubber gloves. They give you a false sense of protection, and they always have a pinhole leak. Tongs are the only way, but you still run the danger of a splash

If you use HF you should always have a tube of calcium gluconate antidote gel very handy.

My use of HF declined precipitously after I bought a CRC tome on lab safety which had dozens of color photos of HF wounds. The ones showing melted eyeballs are quite life changing.

Bart
avatar
Paul Brandes January 18, 2012 11:59AM
Jim Gawura Wrote:
-------------------------------------------------------
> Specimens from the Seneca #1 have been
> the most frustrating to clean for me.

That's not surprising, considering the copper in that area of the Keweenaw around Seneca/Mohawk has a higher concentration of arsenic than most places. No matter what one does in attempting to clean a specimen from there, it never really comes out great.
avatar
Bart Cannon January 18, 2012 11:56PM
I made a mistake.

Seems that it's Bill Boehm who owes me $2.00 for my 50 cent words, not Mike.

Hard to keep track, isn't it. I don't believe that it was me who mentioned "green, black, brown rocks" enclosing coppers.

I do have another suggestion about cleaning coppers that would require $25 dollars of effort to produce a $5 copper.

My EWL air abrasive station has, in addition to its bead blast guns, a very powerful micro jack hammer. It will remove chunks of rock when set to high pressure, and can work more delicately at lower pressure.

Still not an economic solution for coppers, but there is something therapuetic about punishing matrix.

Bart
avatar
Bill Boehm January 19, 2012 02:18AM
Bart, you're wrong. I didn't recognize about 15 or 20 words @ $.50 I do have a question that is very important to me if any of you will respond to it. Is there any particular rock? matrix? that I should not put in a oven and heat it up? Crystals? What about the specimens that you say may have arsenic in them? When working with specimens that have arsenic in them do I have to worry about dipping them in Muratic acid or Tarn-x, vinegar and salt? Do I need to wear a mask or gloves when working with it? Can I tell by color or texture if it has arsenic in it. I am strictly a 73 year old beginner that knows nothing about chemicals or minerals so forgive me if I ask dumb questions. I am going to start a site on talk pages about copper artifacts in the Keeweenaw. Bill
avatar
Bill Boehm January 19, 2012 02:49AM
Paul: I went to the talk pages, scrolled through all nine of them and there were no topics about the Keeweenaw to jump into. I could not find out how to start a new post.

Paul: I scrolled through the nine talk pages and there wern't any topics about the Keeweenaw that I could add to. I could not find a way to start a new post. Can someone tell me how to start one? Thank you.
avatar
D Mike Reinke January 19, 2012 03:47AM
Bill
I'm new enough at this too, but I'd venture to say you can put any rock in an oven. Lava runs in the vicinity of 2000 degrees F, give or take, right? So don't worry, you've got lots of leeway there. Some cherts, I hear, have moisture in them and don't make good campfire rocks because they can blow up, but i have never known of that happening. If others could weigh in on that i'd like to hear...You are talking at most fist sized pieces in an oven, aren't you, I'd guess. Baking a turkey sized hunk of pure arsenic may not be wise, but the little in copper, I can't see any danger, IMHO.
I also don't think there are too many minerals that would ever need, or could withstand, this kind of abuse. horrible cruelty!
There was a great thread on safety just recently. Go to the home page, upper right,and at 'search for' scroll to messageboard and type 'arsenic and cinnabar' and that thread will come up. It'll put your mind at ease. Mineralogy is not extreme sports.not usually.
Muriatic acid is dicier stuff. I only use it outdoors.

Bart, great comment on 'punishing matrix', so true!

Mike
.
avatar
Bill Boehm January 19, 2012 04:33AM
Went to localities, to top right, typed in copper artifacts and the keeweenaw, hit search, clicked on new topic.......came back at me "sorry, you do not have permission to post/reply on this forum" ! getting really frustrated.
avatar
D Mike Reinke January 19, 2012 05:35AM
Bill
Localities might work better if you give it less. i found that using one key word would get me close, then i could scroll though what came up, i.e. type in just a county, then when all the states came up, scroll to michigan and you might find what you want. Managers could help more, but this has got me through .
mike
avatar
Bart Cannon January 19, 2012 03:28PM
Bill,

I would avoid oven treatments of mercury ores, thallium ores and realgar bearing rocks. I don't think that arsenopyrite will release arsenic oxide fumes at 300 degrees F.

There are extensive discussions about the dangers of minerals someplace on the website.

Good news. I've decided not to bill you for my 50 cent words. Just reading them is enough penance.

Bart
Your Email:


Spam prevention:
Please, enter the code that you see below in the input field. This is for blocking bots that try to post this form automatically. If the code is hard to read, then just try to guess it right. If you enter the wrong code, a new image is created and you get another chance to enter it right.
CAPTCHA
Your message:
Attachments:
  • Valid attachments: jpg, jpeg, gif, png, pdf
  • No file can be larger than 9.38 MB
  • 3 more file(s) can be attached to this message



bannerbannerbannerbannerbannerbanner
Mineral and/or Locality  
Mindat.org is an outreach project of the Hudson Institute of Mineralogy, a 501(c)(3) not-for-profit organization.
Copyright © mindat.org and the Hudson Institute of Mineralogy 1993-2016, except where stated. Mindat.org relies on the contributions of thousands of members and supporters.
Privacy Policy - Terms & Conditions - Contact Us Current server date and time: December 11, 2016 08:05:11
Go to top of page