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Techniques for CollectorsHow should I clean white sediment on quartz + spessartine?

16th Sep 2019 20:19 BSTTama Higuchi

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Hello all!  This is going to be my first time attempting to clean a specimen.  I have this really beautiful Smoky Quartz and Spessartine piece with a great aesthetic (photo doesn't do it justice :-D), but the white, powdery substance stands out a bit much from the dark quartz.  I would love to clean it off, but I'm not quite sure how to go about it.  I'm considering letting it soak in vinegar, but I don't know how that would react to Spessartine or if it could make them loosen.  I'm not even sure what the substance is.

Locality is Wushan Spessartine mine, Tongbei, Fujian, China

Any advice is very appreciated!

16th Sep 2019 20:48 BSTBob Harman

TAMA,     You have a very nice specimen as is.    If you really feel compelled to try and clean it further, here is what I might do.     Know that the whitish crust in the crevices is minimal so a very short 1-2 minute soaking in vinegar should be sufficient to lessen or remove it, if the vinegar works at all. Rinse the specimen well and then gently try to get into the crevices with a hi pressure cleaning gun set on the lowest setting followed by a final rinse.     Otherwise I would do nothing.     CHEERS.....BOB  

16th Sep 2019 21:16 BSTTama Higuchi

Hi Bob!  Thank you very much for your reply.
I just finished doing two 2-minute soaks in household vinegar, then rinsing with water and drying.   I see a little difference, if any.  I don't have access to a cleaning gun, instead do you think it would be possible to let the specimen soak in vinegar for a bit longer, maybe half an hour?

17th Sep 2019 21:42 BSTJobe Giles

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It’s hard to tell from the photo but the white residue could even be powdered silica that settles into and became a part of the crystal. I often find that the crystals that I mine from pockets that have spessartine or tourmaline in them often are etched and then have a similar appearance. If it is a feldspar or some other clay, I am sometimes able to loosen and remove it using Whink Rust Stain Remover (brown bottle). Using undiluted solution and short soaks (-15min per soak) shouldn’t etch the garnets or quartz. Soak in water after for at least a few hours. Also, if you’re not opposed to treating the quartz, light mineral oil applied with a very fine tip paint brush may hide it. I’d personally try the Whink but only for very short soak. The way I would do it is soak in warm water for several hours, then move into whink for about 10 min, clean with a toothbrush or high pressure sprayer on lowest setting. Then place back in clean water to soak for an hour or more before allowing to dry, if there is a difference but if it needs it again, I’d repeat in the same order. 

17th Sep 2019 22:19 BSTKevin Conroy Expert

Before trying to clean this, if you have an ultraviolet light see if the white fluoresces.   If it does, it's most likely hyalite opal (opal -AN).   If it doesn't fluoresce it may be a secondary deposit of quartz.    If either of these are the case you can pretty much forget about trying to remove it.

17th Sep 2019 22:33 BSTJobe Giles

You’re absolutely right, I forgot to say that about the micro silica, it doesn’t come off, which was also why I included the photo. It was implied but not said. Glad you chimed in with that. I have found the the hyalite that I find on some of my quartz does become loosened with extended soaking in Whink. But it has to basically be scraped off. It’s easy to see under SW UV as it lights up green. 

18th Sep 2019 16:16 BSTTama Higuchi

I don't have access to a UV light, but I'll see if there's a place at my university that can light up my specimen for me.  The "residue" on my piece looks VERY similar to the photo you attached, so you're probably correct in that I won't be able to remove it.  Thank you, Jobe and Kevin, for this information; I had no idea about micro-silica and hyalite opal :-)

21st Sep 2019 23:00 BSTDana Morong

Be careful when using Whink Rust Stain Remover, as it contains HF (hydrofluoric) acid, which can be very hazardous to human skin.  It should only be used by those who know all the hazards of using it.  I know that this is true, as I looked up the material about it (both about Whink Rust Stain Remover containing HF, and on hazards of HF), also have read about its effects upon human skin (so I am not confusing it with hydrochloric acid, HCl, which I have used several times in mineral testing years ago).  Personally, I would not use HF acid at home - only in a lab environment with proper outflow ventilation, and rubber gloves.  There was a letter, and comment by editor, in Mineralogical Record, January-February 1993, volume 24, n.1, page 56, about the hazards of HF acid.  It ended with "Most dealers consider HF too dangerous to work with, and will farm out the work to a chemist if necessary.  Collectors should certainly never use it in the home environment."

22nd Sep 2019 04:12 BSTJobe Giles

I use it regularly, I also don’t use a cent hood, I use standard kitchen cleaning gloves and have had no adverse results. Please note the whink rust stain remover is only 3% HF acid. I think that you’re right that it deserves respect however this is by no means the same lab grade material used in professional applications. If the were the case it would eat or at least heavily etch the quartz rendering it useless. Also, a high concentration solution of HF acid would not be sold on the shelves of almost every hardware store across the US. Use gloves, but by no means do you need to be so afraid of this solution, I am going on over 7 years of using it. I have used many other acids at full strength and am by no means a “professional” chemist. I simply don’t agree with your cautionary post. Read the label, read the MSDS, use due caution, but don’t be scared. 

22nd Sep 2019 04:21 BSTJobe Giles

Just to be clear, your comments about what it can do to your skin and my rebuttal of the strength of this solution. I have on many occasions come in contact with this acid, meaning, I have had it on my skin. It has not done anything worse than cause some drying to my skin, no worse than iron out or any other acid. That is to say that, this 1.5-3% solution is nothing to be compared to the high lab grade concentrations. If need be you can purchase calcium glucanate no apply to areas where you suspect contact may have occurred so that the acid attacks the calcium in the gel rather that in your skin. 
 
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