How do you clean iron stains off quartz?

[lizziebird]

... like the orange and black staining on the quartz crystals from Diamond Hill? I have a bunch of very nifty looking orange and black crystals but I'd like to see some of them w/o the staining. I have no idea what I"d use to clean it off.

Thanks!

[Doug]

Start off with Super Iron Out cleaner. It is available at most hardware stores and works well. If that does not get the red out you can try oxalic acid (wood bleach) or step up to muriatic acid-but be VERY careful, it can burn. The black stains are NOT from iron, they are manganese I believe-and they are there to stay. I recommend you clean some of your Diamond Hill treasure and leave some as found. I really like the ones I left the stians on better now!!!

[lizziebird]

I actually like the different colors of the stained quartz too, but I do have a few pieces that I think would look really nifty if they didn't have the orange coating on them. I'll give the super iron out a try. Thanks!

[fredda]

Lizziebird--
I found that Super IO at my Walmart. Look back where they have the toilet cleaners.
HTH, fredda

[sapphiregirl]

I like the source of where to find as I have a client that has a lot of iron in her water. Right now Oyclean helps with the laundry and sink. I tried the IO on her sink as well as on the crystals that Donald got at Diamond Hill. Some people believe it or not like the orange and black on it. To them it verifies the fact that these were formed from volcanic lava. It is mangese that makes the black.

[wesman]

the best thing to clean iron off is oxalic acid. it will remove both iron and manganese. if the iron is very heavy then use muratic. but for them to work well, they both need to be heated. the best way is in a crock pot, but alow ample time for them to cool before removeing them or they will crack or shatter.

[geodepat]

:oYou forgot to say use the crock pot [glow=red,2,300]OUTSIDE[/glow]

[chet]

As the owner of the Diamond Hill Quartz Prospect, you can imagine that I've spent some time figuring out how to clean the specimens. After you wash off the dirt/clay, you first need to decide if the specimen looks better with the stains, or whether it might look better with the stains removed. Generally, I like the stains. However, if the stain is spotty and not aesthetic, or if the piece is dinged such that the ding highlights the underlying white quartz relative to the stain, then cleaning is probably a good idea. Also, it is generally (but not always) a good idea to clean smoky quartz and amethyst crystals.

Both Super Iron Out and oxalic acid will remove the iron oxides (tan, yellow, orange, brown) and manganese oxides (black). In fact, the manganese deposits, if not thick, are dissolved away very quickly. I have not found hydrochloric (muriatic) acid to work well, and it is much more dangerous than Super Iron Out or oxalic acid.

An advantage of Super Iron Out is that it is relatively safe, but it should still be used outside. Disadvantages are that it is expensive and takes a long time to work. Another disadvantage is that the solution does not remain effective for a long time -- it undergoes some chemical change that eventually (weeks to months) makes it ineffective.

Oxalic acid works fine when it is heated. Of course, you should not heat it in a metal container (it will dissolve the container), nor in an enclosed space (danger of fumes and spills). Outdoors, or with something like a crockpot in an outdoor shed, are both acceptable. Without heating the oxalic acid solution, it takes quite a while (up to many weeks or longer) to clean the stains in the cool season. However, when I leave specimens in solution in a sunny location in warm weather, it takes just 1-3 days to clean them. Additional advantages of oxalic acid are that is inexpensive, and it does not seem to lose its potency over time.

Use a saturated solution of oxalic acid. Use rubber gloves when putting specimens into or out of the oxalic acid solution. When a piece is done being acid-treated, take it out of solution, hose it off, then put it in water for several days. Then hose it off again and let dry. If the specimen has a lot of porous rock, then maybe give it a second time in a fresh water.

Over time, the oxalic acid solution will become a deeper and deeper color of greenish. Eventually, it might stop cleaning crystals because all of the oxalic acid molecules get used up. But don't worry about the green color -- it disappears when you water soak the specimen.

We sell oxalic acid (solid granules, looks like sugar) at $2.50/Lb, with a minimum of 4 Lb. We don't ship it. You need to pick it up at our place, and you also need to bring your own container to carry it. A plastic container with nicely closing lid is optimal. You can get our contact info at: www.gamineral.org/commercial-diamondhill.htm.

Chet Karwoski
Diamond Hill LLC

[lee]

When I have used acid in the past, I have had some problems with the base rock turning yellow. I have tried soaking the piece in baking soda and clean water; but the yellow stain persists. I have never had a lot of problems with staining of the materials when using iron out but have had some problems with a white chalky stain developing in cracks of clear quartz. Any suggestions? Finally, as Chet has stated, most of the Diamond Hill skeletal crystals are beautiful with their coatings still on. I simply clean them and give each a good coating of mop and glow floor polish. This deepens the color and gives them a nice luster.

Lee

[dixieeuhedrals]

oxalic acid is notorious for staining base rock yellow , especially anything that is porous or has cracks . Once the acid is super saturated with iron & turns greenish yellow , its about time to discard it . Porous rocks such as the sandstone that the arkansas quartz crystals grow on is very susceptable to the yellow staining. The problem in part is that when the rock is heated the pores open and it absorbs the acid . When the rock cools the pores seal up and seal the yellow into the base. I have read on some message boards that it helps to soak porous rocks in water prior to the acid. I have also heard that battery acid will dissolve the yellow staining . The folks in Arkansas give away or sell for pennies the specimens that have the bases stained yellow .

[wesman]

most differently OUTSIDE. my bad. my experience is in mostly only cleaning quartz crystal. i've tried things like iron out or CLR but their more problematic than oxalic. if i have problems with yellow staining, i dip them in fresh muratic for just a bit, an hour or so, this usually removes the yellow. if you use muratic and have staining then soak them in oxalic and it will remove what ever the muratic left. a crock pot with a ceramic cooker works fine for a few months with oxalic and about a month with muratic. stainless last longer but are more expensive. if a crystal has etching or fog, that won't come off. it doesn't shine them up, just cleans them off.

[chet]

Lee makes a good point that I forgot about: SIO never leaves any yellow stain.

With Diamond Hill specimens cleaned with oxalic acid, I rarely see the yellow staining, and only in matrix (never on crystals). As Rodney says, the porous matrix is worst for developing yellow stain. For Diamond Hill matrix specimens, it is important that, after acid cleaning, you soak the piece in water for a long time (around 3-4 days). It can take many days for all chemical residues to diffuse out of the small cracks. And if you clean a very large specimen (like a foot or more), and if it has porous matrix, then it might take weeks (or more) of water-soaking in ensure no yellow staining will appear.

I also agree with Rodney that the oxalic acid solution should be discarded when it turns deep green. My reason is that I can't see what's going on when it's deep green! But it still works fine. When you discard the oxalic solution, think about where you are putting it -- septic tank is risky as it might kill bacteria; and if you pour it on grass, the grass will die.