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A general guide for using the Forum with some rules and tips
Removing stubborn minerals from quartz
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GneissWare




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PostPosted: Feb 19, 2017 11:57    Post subject: Re: Removing stubborn minerals from quartz  

Virtually nobody who professionally cleans rocks uses oxalic acid for iron stain removal. In the USA we have a powder called Super Iron Out (SIO), which essentially created a Waller's solution that is very effective at removing iron coatings. It is less toxic and has a pH of about 6.5 so it effective on many things. You can google either SIO or Waller's solution for the chemistry.
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PostPosted: Feb 19, 2017 13:04    Post subject: Re: Removing stubborn minerals from quartz  

GneissWare wrote:
...You can google either SIO or Waller's solution for the chemistry.

Much easier, read this thread from its start! 😉 (or also write the word "Waller" in the Search for a text tool...)
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Pierre Joubert




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PostPosted: Feb 19, 2017 13:11    Post subject: Re: Removing stubborn minerals from quartz  

Hi Gneissware. In places like SA, we do not have Super Iron Out, and ordering it from the USA is expensive and problematic. I recently asked a local chemical company for something similar to SIO. I used the product but with very little effect. I bought chemicals to make my own Waller method solution, but this also had no effect. Ronnie Mc Kenzie told me that he has used Aluminium cleaner effectively on some quartzes and I tried it with great effect on quartz specimens with clay from areas that are rich in manganese. It also dissolves manganese coatings on crystals. I tried it and it works well on specimens from mentioned areas.

To David I want to say that your specimen, no matter how insignificant to others, is special to you and clean it as best as you can. If you can get hold of SIO, take Gneissware's advice. If you cannot get hold of it, oxalic acid should do just fine. If your oxalic acid solution is too strong, you will have a yellow staining, which is easily removed with pool acid (careful please with the latter).

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PostPosted: Feb 19, 2017 13:32    Post subject: Re: Removing stubborn minerals from quartz  

Pierre,
Manganese can be removed with HCl. Waller's will not have any effect.

Many Aluminum cleaners contain a few percent of HF which will clean microcrystaline quartz off larger Quartz crystals. It may be weak enough not to remove luster. The problem is that HF is not safe at really any concentration, particularly if you don't follow all precautions.
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Pierre Joubert




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PostPosted: Feb 19, 2017 13:48    Post subject: Re: Removing stubborn minerals from quartz  

GneissWare wrote:
Pierre,
Manganese can be removed with HCl. Waller's will not have any effect.

Many Aluminum cleaners contain a few percent of HF which will clean microcrystalling quartz off larger Quartz crystals. It may be weak enough not to remove luster. The problem is that HF is not safe at really any concentration, particularly if you don't follow all precautions.


Hi Gneissware. I have a few quartz specimens coated with Psilomelane. If my memory is correct, HCI did not remove that. I will check again and let you know. Like you, I have tried a number of acids and find that some works to remove some coatings and others work for others; some coatings are only removed by using first the one and then the other. I have read a number of articles on cleaning quartz, but yet have to find one that covers the topic sufficiently. I will not easily remove oxalic acid from my 'cleaning' toolbox, as it works quite well for common cleaning.

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PostPosted: Apr 19, 2017 08:34    Post subject: Re: Removing stubborn minerals from quartz  

Hi GneissWare, I took a low quality quartz specimen with Psilomelane and left it in pool acid (HC) for about a week. I found no notable corrosion. See photo.


P1260523.JPG
 Mineral: Quartz with Psilomelane
 Locality:
Ceres, Warmbokkeveld Valley, Witzenberg, Cape Winelands, Western Cape Province, South Africa
 Dimensions: 42 x 32 x 16 mm
 Description:
 Viewed:  1603 Time(s)

P1260523.JPG



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PostPosted: Apr 19, 2017 08:50    Post subject: Re: Removing stubborn minerals from quartz  

Since I started this thread, I have experimented a lot and, thanks to our good friend Ronnie McKenzie, discovered a very valuable acid called Aluminium Bright Cleaner. He used it to clean the monster quartz (with ajoite specimen) that was displayed at Tuscon. I hope to hear from the manufacturers soon what the composition of the acid is.
I find that this acid works very well on quartz specimens from KwaNdbele, Vredendal Lime Quarry, specimens from a certain gorge near Worcester (Western cape) and also quartz specimens from the Northern Cape.
Oxalic acid works very well for specimens from our direct area (Ceres, Western Cape).
Pool (HC) acid works well for Erongo and Brandberg quartz crystals (Oxalic acid also works very well with BB quartz specimens).
When other minerals like calcite is present (unless you want to remove that to), these acids must NOT be used.
I discovered that in different areas, the 'glue' that binds the clay is made up of different minerals and only experimenting can tell you what works for what.
My years of frustration has finally come to an end and I have a very high success rate in cleaning my quartz specimens, as I now know what cleans what.

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PostPosted: Apr 19, 2017 23:11    Post subject: Re: Removing stubborn minerals from quartz  

Many aluminum cleaners contain HF or ammonium bifluoride (which is a buffered form of HF). So, check the SDS and be careful.

Psilomolene, by the way is a bit harder to remove. More sooty Mn oxides will come off with HCl.
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PostPosted: Apr 20, 2017 03:23    Post subject: Re: Removing stubborn minerals from quartz  

GneissWare wrote:
Many aluminum cleaners contain HF or ammonium bifluoride (which is a buffered form of HF). So, check the SDS and be careful.

Psilomolene, by the way is a bit harder to remove. More sooty Mn oxides will come off with HCl.


Hi Bob, thank you for the warning and comment. I am a bit slack and never use gloves. I need to change that. Fortunately I use a bucket with holes in the bottom, with a handle, that fits in a slightly larger bucket with the acids. I do wear safety goggles when I use HC acid.

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PostPosted: Apr 20, 2017 09:03    Post subject: Re: Removing stubborn minerals from quartz  

HF (hydrofluoric acid) is orders of magnitude more dangerous than HCl (hydrochoric acid, muriatic acid).
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PostPosted: Apr 20, 2017 09:38    Post subject: Re: Removing stubborn minerals from quartz  

GneissWare wrote:
HF (hydrofluoric acid) is orders of magnitude more dangerous than HCl (hydrochoric acid, muriatic acid).


Hi Bob, thank you for reminding me of that. The company has confirmed that there is indeed HF acid in the mixture. I will have to take extra care. What minerals (and from where) do you usually clean?

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PostPosted: Apr 20, 2017 09:59    Post subject: Re: Removing stubborn minerals from quartz  

I clean anything needing it. I have a full lab with air scribes (3 kinds), air abrasion, acids, etc. I mostly end up using Waller solution (premixed here as Super Iron Out), phosphoric acid and abrasion.
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PostPosted: Apr 20, 2017 11:26    Post subject: Re: Removing stubborn minerals from quartz  

Sounds very interesting! It is a pity we are so far apart. I would have liked to learn from you.
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