FMF - Friends of Minerals Forum, discussion and message board

[MSrockhound]

How can I clean this quartz of what appears to be rust buildup? I want it to be clean but I don't want to ruin the crystals.

[Jordi Fabre]

Please use this link: https://www.mineral-forum.com/message-board/viewtopic.php?p=795#795

You can use for your Quartz Oxalic too, following the suggestions of Pete Modreski.

Jordi

[John S. White]

Are you sure that you want to remove the iron oxide partial coating? It is natural and, to me, it looks rather attractive. The specimen may have more character as it is than it would if you remove the yellow-brown coating. Like it or not, the coating is another mineral and it says something about the history of the quartz.

[ikram]

cleaning of quartz means removing an Iron stain , some clay , calcite coat Or an organic stains (moss , molds) etc.your one is looking Iron Oxide coat you want to remove.
use Super Iron Out.
ikram

[Jon Mommers]

I agree with Jordi and Ikram, either product will remove what appears to be iron staining.

To me it appears that someone may have already tried.

The staining in the cracks and crystal contacts will be especially difficult to remove, the lose of this internal contrast due to the yellow staining, may also spoil the aesthetics of the specimen.

If you decide to clean the specimen chemically please read and follow the safety data sheets for any products that you use. The fumes from both Oxalic acid and Super Iron Off can be very nasty, make sure you work in a well ventilated area.

When finished ensure you neutralise any residual chemicals both from the specimen and also spent chemicals.

[Druid]

We have a similar problem with Quartz from the Orange River area on the South African border. A warm solution of oxalic acid left for about a week normally helps. With tougher stains an ultrasonic cleaner may be necessary.

[alfredo]

I'm going to play devil's advocate here:

Collectors always ask how to clean "mineral X", rarely do they take much trouble to analyze the "dirt" ("mineral Y"), but knowing the identification of Y (not just guessing) is just as important as knowing the identification of X.

Typically we think of brown stains as being "limonite" (Fe oxyhydroxides), in which case there are many possible chemicals for cleaning, as already mentioned by other posters: sodium dithionite, Waller solution, oxalic acid, hydrochloric acid, citric acid.... But sometimes collectors complain "I tried .... acid, but it didn't work; what can I do?". That's probably because your "limonite" is not Fe-oxyhydroxide. Brown stains can be many other things too, like Fe arsenates/phosphates or Fe silicates (hisingerite), which won't be affected by the usual chemicals. So let's have more analyses of "dirt"! Who knows, you might even find a new mineral, which you then won't want to remove anymore.

[Druid]

You make a very good point Alfredo. One of our club members recently tried to clean some amethyst geodes of what he thought was a calcite build up. After nearly a month in hydrochloric acid the white substance still had not come off. He took it to be analyzed and found it to be a fairly rare mineral. Unfortunately, I can't remember what it was, but I do know that apart from being surprised at the find he was also incredibly happy.

[jimB]

I'm sure I'm late here, but I think the piece is nice looking with the stain. After you turn it into transparent rock crystal, it will look ordinary. I'd leave it alone.

[Jason]

I also agree that it should be left with the staining..makes it more unique..everybody and their brother, mother, and sister has clear quartz..keep it original..if you do choose to clean it use what ikram said and get some super iron-out..much "safer" than oxalic even though both are very mild..fumes are not nearly as bad either

[Darryl]

I like the looks of the mineral as it is and would not clean it. But, since the question has come up - Has anyone tried using a mild (3% +/-) solution of hydrogen peroxide to clean such samples?

I ask because a few years ago I used much stronger solutions (30%) to dissolve the manganese oxide cements out of a black sandstone on which I was working and it stripped every bit of it out. Of course at that concentration it also gave off lots of heat and bubbled violently, but 3% solutions were very tame. Either concentration sometimes left a murky hydroxide behind if I didn't flush the samples with enough water but other than that I had no problems.


Referring to the article on cleaning pyrite - I have had some luck using hydrogen peroxide to clean pyrite but do not know about any long term effects it may have had on the samples. In my current job I use it as a test for the presence of micro-amounts of pyrite in the cuttings from oil/gas wells as they are being drilled. The most obvious problem with this application is that the pyrite is most frequently found in black shales and the peroxide will oxidize the carbon in the shales. If you don't look smell the vapors coming off for sulfur you may think you have sulfides in the samples when you do not.

[Matt_Zukowski]

Hydrogen peroxide is a strong oxidizer and should be not be used to clean pyrite. The thing you don't want your pyrite to do is oxidize.

Also, iron staining on minerals is usually a mixture or oxidized iron and other metals (manganese). A strong oxidizer should not do any good for removing such stains. Acids will dissolve such stains, so the treatments suggested above are the way to go.

[Darryl]

Matt,

Thanks for the cautionary note about cleaning pyrite. I agree hydrogen peroxide is a strong oxidizing agent and I am glad you said people should not use it to clean pyrite. I put my little bit in about having done so because it appeared to work in the short term but I have not been around those samples for several years and don't know what they look like now. Fortunately they were less that great (hardly even good) samples. Now I know never to do it again.

I am going to start a new message sequence concerning the reaction of hydrogen peroxide on metallic oxides hoping to get some information from someone more knowledegable about chemistry than I am - perhaps you again. I don't know if it will remain in this category or not.

[Mineral Fan]

I should have joined this forum before cleaning my quartz...

[SteveB]

I agree. Take care and think WHY are you wanting to clean a specimen. In this case its not NEEDED. Typically cleaning with water is all that's needed to remove surface dirt, but you only need to remove enough to ensure your shelf isn’t going to get covered in dirt. You do not need to remove every last grain. And Alfredo mentioned, the dirt is part of the story of each specimen and retains scientific value of the specimen. Once its all removed that information is lost forever. Even worse is people who “polish” the sides of crystals to “enhance” then making them totally worthless in the process, both aesthetically and scientifically. Most such polished crystals on the market are just cut waste quartz material and not naturally formed shapes..

Another major issue with cleaning is you don't know what the discoloration is nor how it will react chemically with cleaners. I’ve seen some specimens “foam up” in their matrix and cracks as new and exposed compounds slowly react with the air causing new growths to occur and these were like a plant pushing up through a crack in pavement. The pressure of the growth was enough to break a specimen weeks or months later. It could also be what you are trying to clean is structurally integral to the specimen.

Simply, odds are you are far more likely to damage a specimen using anything harsher than plain mildly soapy water. Unless you know what you’re doing, do nothing.