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Techniques for CollectorsCleaning Clay Off Galena

30th Dec 2006 18:19 UTCAnonymous User

Hello all!

I recently purchased a fine cluster of Galena with some Quartz,from Madan,Bulgaria.The piece is great,big as 23x10x7 cm and has a lot of mirco-caves between the crystals and sub-clusters with crystals smaller than 1mm,which makes it really beautiful.The problem is that the piece was covered totaly by green clay,very hard to be removed mechanically.I tried to clean some of it with a toothpick,but it's impossible to clean all of it this way,at least not damaging Galena.I also let it in warm water for one day or so,but could not remove much of it.

Any idea on how to clean it(mechanically or Chemically)not damaging the Galena or the Quartz.???

Thanks in advance!

-Kostas.

31st Dec 2006 04:38 UTCAlan Plante

Hello Konstantinos

Have you considered a "water pic"? Get a fitting for the end of a garden hose that has a separate screw-on ring. Get a heavy-guage metal disk the diameter of the inside of the screw ring. Drill a tiny (1/32" or 2mm) hole in the middle of the metal disk. Place the disk inside the screw ring and screw the ring onto the end of the garden hose.

Depending on how far you turn the water on, this will give you a small gentle stream to a dangerously high-velocity "jet blaster" stream. A strong stream can have enough force to strip paint off car bodies and bore holes into wood. So be careful the first time you turn the water! (Make sure you have a very strong grip on the hose, too! :~} )

Water pics are handy for getting a strong jet of water down into nooks and crannies in specimens - blasting out stubborn clay or dirt, even somewhat loose rock particles in the matrix. You have to be careful using them on crumbly matrix until you become experienced at judging the force of the water stream - or you could litterally blow specimens apart.

Be sure to keep the kids and pets at a safe distance - and make sure you don't aim the stream at anything it could damage. I usually use mine inside a 55 gallon drum set up sideways on saw horses - so that all I'm battering with the jet of water is the inside of the drum. (I did this one day with a drum that the bottom had rusted out in, and blew holes through the bottom before I realized I had a problem. Fortunately, the cats were in the house, and the neighbor's kids were not around... :~} ) I set it up with the front (open end) of the drum a little higher than the back end, and drill some drain holes in the rear "bottom" of the drum wall. This way the water runs towards the back of the drum and drains out through the holes.

Anyway, I've found a home-made "high-pressure washer" - or "water pic", as it is often called - to be quite handy for blasting stubborn clay out of deep nooks and crannies in crystal clusters.

Good Luck!

Alan

31st Dec 2006 06:12 UTCRay Hill Expert

I solved this kind of problem this year with a "stain removing" spraying tool that I picked up from from Mikon at Tucson this year. It can be adjusted from a gentle spray to 1600 psi and is the size of a small paint spray gun. It should still be listed on their site as a mineral cleaning gun or some such.

31st Dec 2006 18:47 UTCAnonymous User

Hello again!

Guys,thank you all so much for your replies!I thought of a water gun and the truth is that I didn't try it so far,but I'm very afraid that this will destroy the specimen,because the quartz crystals are very small,and so easy to unstuck and damage the galena,as harder mineral,but also smaller galena clusters may unstuck from the main bigger clusters.

I would be grateful to you if you take the time to suggest a chemical way,if this is a good idea(it doesn't destroy the specimen...)!

Thanks a lot once again and in advance!

Happy new year!

-Kostas.

P.S.-Where could I find info on what kind of Galena is considered valuable?There are all kinds of Galena in Bulgaria,all beautiful,but I don't know what is the best to get.Any advice?

31st Dec 2006 20:09 UTCAlan Plante

Hi again, Konstantinos

I'm afraid that any chemical which would dissolve the clay would also damage the galena and possibly other minerals on the specimen or in the matrix. Mechanical methods are the only way to deal with the clay in this situation.

The thing to do, once you have a water pic, is to experiment with the amount of pressure it generates - turning the water down or up. I think you will find a setting which will blast the clay out without disturbing the other minerals. Just don't experiemnt using your best specimen - try one of the poorest specimens first. If all you have is the one specimen, try the water pic on the back, a corner, or an edge - so that if it damages anything the spot can be trimmed to make the specimen look its best again.

Happy New Year!

Alan

31st Dec 2006 21:30 UTCColin Robinson

Hi,

I've had pretty good results removing tenacious clay from between crystals by using some of the proprietary stain removers containing sodium percarbonate. They have various names: Oxi, Cillit, etc. but these are a bit of a rip-off. Try to get hold of an own brand. the one I use costs 99p (about 2 US dollars) for a 500g tub. Bio-Tex is also pretty good but that also is quite expensive if you are using large amounts.

2nd Jan 2007 06:23 UTCJim Bean 🌟

Alan's water jet simplified:

Brass cap with garden hose threads.

Get the smallest drill bit available where you get the brass hose cap. Drill a tiny hole in the cap and you have a high pressure water jet, capable of destroying delicate specimens and improving tougher ones...

Getting back to non brute-force methods, has anyone tried SAPP (sodium acid pyrophosphate) to loosen stubborn clays?

2nd Jan 2007 19:18 UTCJesse Fisher Expert

Most clays are phylosilicates (micas), which are impervious to most acids - even HF to varying degrees. Strong alkali solutions will attack silicates, but anything that would do something to your clays would do even more to the rest of the specimen. Fortunately, clay deposits are often a mixture of clay minerals, carbonates and/or iron oxides/hydroxides, which are easier to remove chemically, leaving the clays loosened and more readily removed by mechanical means such as water gun or ultrasonic bath. A soak (a few days to a week) in a dilute phosphoric acid may do this without harming the galena, unless the galena has some anglesite alteration, inwhich case you would want to use something like dilute HCL instead. As with any chemical cleaning technique, it is always best to have a "sacrificial" piece to try on first, incase something unexpected happens.

2nd Jan 2007 21:08 UTCMark Rheinberger

Hi Konstantinos,

I get good results most of the time using an ultra-sonic cleaner. Your problem might be the size of your specimen as you will need a large cleaner to do the job. If you know someone with an ultra-sonic cleaner its worth a try.

Mark.

4th Jan 2007 20:54 UTCAnonymous User

Hi all!

Thanks you for you your answers,I really appreciate it!Maybe the ultra sonic cleaner is the best idea,but I don't know anyone with such a machine.The specimen is big and I may need a bigger cleaner.These cleaners are very expensive and i don't think buying one,so maybe I'll try the water gun.Anyway,I am about to sell or trede the specimen,so the new owner may clean it better.

Thank you all!

-Kostas.

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