FMF - Friends of Minerals Forum, discussion and message board

[barbie90]

I want to get rid of white straches on my tourmaline but ı dont know how to do ,on a page on net ı have read some oils are helpful ,what kind of oil must ı use? thanks

[Jesse Fisher]

Mineral oil - sometimes also known as liquid paraffin - will work for this. It is available at most chemists/drug stores. Brush on a light coating, wait a day or so for it to penetrate, then wash of the residue with a bit of detergent.

[robynahawk]

While we are on the topic...how do I removed the hard white deposits on my California Tourmaline pieces?

Normally I cut my stones - so I never had to deal with this - but I have a couple that I would like to keep as specimen.

Robyn

[John S. White]

[Jesse Fisher]

Not knowing what "hard, white deposits" are exactly, it is hard to say how to deal with them. If they are a late-stage overgrowth of fine-grained clays or feldspar, the best way to remove the from the crystal is with an air-abrasive unit. If, however, these are part of a matrix to-which the crystal is attached, I would agree with John and suggest that it be left alone. If you can post a reasonably sharp and detailed photo, that would help.

[robynahawk]

Sorry Guys - I should have been more descriptive. Not Quartz or Clevelandite (sp) but that white/grey clay that doesn't just wash off.

Jesse - if I don't have an air abrasive unit (which I assume is like a sand blaster with out medium) is there an acid bath?

Robyn

[Jesse Fisher]

The coating you are interested in removing is likely a fine-grained mica and/or feldspar. The only chemical that might remove it would be hydrofluoric acid (HF). This stuff is EXTREMELY toxic and should not be handled by anyone without proper equipment and training in chemical safety. Removing by a mechanical method is likely your only option. Air abrasive units are commonly used by full-time mineral dealers to prepare specimens for sale. If you can locate someone who has one they would likely clean your specimen for a small fee. One of the Chinese spot-cleaning (water) guns might also work. When all else fails, there's always a dental pick and patience.

[barbie90]

hello jesse thanks for your help ,do you know any method for getting rid of micas on corundum ,ı have 7 corundum minerals ı want them to look better ,by the way ı cant clean mud on my calcites too how can ı do .
regards

[GneissWare]

The water guns will work fine for removing mica and "mud". Presoaking the calcite will soften the mud making removal easier. Search on ebay for ALBATROSS ELECTRIC SPOT CLEANING GUN -- they are under $100.

[barbie90]

thanks geiness ı really appreciate it,by the way ı used parrafine ıt softned the look of the straches

[ellencmoe]

Hi Robyn,

The guys at the Oceanview Mine have told me to soak the specimens in Super Iron Out and then use a water gun to clean the tourmaline specimens. I have variable success with the Super Iron Out - sometimes it gets quite a bit of the clay off. I still have to buy a water gun.

I usually start out using BarKeeper's Friend - a common kitchen cleanser powder which is has oxalic acid. Just wear gloves whenever using anything with oxalic acid - it can be absorbed thru the skin and possibly result in kidnet stones. I use an old toothbrush and scrub.

I also soak specimens in oxalic acid solution.

[ellencmoe]

From the picture it is hard to tell if there are white scratches on the surface of the tourmaline or if the white lines are internal fractures (or some of both). The tourmalines form the southern California mines tend to have a lot of inclusions and internal fractures. Personally, I prefer not to treat my specimens in any way except for cleaning them.

[robynahawk]

Thanks Ellen - I really appreciate you taking the time to respond - I knew there was something a little less toxic ;-p

I've used Super Iron Out on Quartz but never on Tourmaline will have to give it a try.

Robyn

[GneissWare]

When using chemicals, particularly oxalic acid, use distilled water not tap water. Southern California water is quite hard and if used with oxalic acid can form calcium oxalate which will leave a yellow residue that WILL NOT come off. I use distilled water with all chemicals, except for use with HCl and phosphoric acid.

[robynahawk]

[chris]

And to complete just in case, oxalic acid can cause calculus (don't know if it is the proper medical word) if absorbed. So handle it with care in a ventilated room.

I think Tracy knows much better than I do on this part, so correct me Tracy if I'm wrong.

Christophe

[GneissWare]

Like any other chemical one uses, one should always review the safety data so the hazards and precautions are known. Oxalic acid is a poison but the dose is high. Following common sense precautions, like wearing gloves, goggles when using acids, not breathing in powders, will get you a long way on the safety front.

For oxalic acid you can review info at:
https://www.cdc.gov/niosh/docs/81-123/pdfs/0474.pdf
(link normalized by FMF)

[Tracy]

Hi Chris -

"Causing (renal) calculi" is another way of saying "causing kidney stones." And this is correct with oxalic acid. Oxalic acid is also severely irritating and corrosive at high doncentrations, and fatal at ingested doses as low as 5 grams (is that a high dose?). Read up on the chemical hazards and follow good safety procedures, as Bob suggests. This is good practice when handling any unfamiliar chemical.

- Tracy

[robynahawk]

Thanks to everyone for your responses - I think I have enough to give it a go.

...and a big thanks to Barbie90 for starting this thread! ;)

Robyn

[ellencmoe]

Excellent advice to use distilled water. The first time I used oxalic acid, I used southern California tap water and forgot to check on the quartz points I was soaking for over a month. By that time, they were totally encrusted and after numerous attempts to re-clean them, I just had to throw them out.