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Techniques for CollectorsCleaning Phosgenite

20th Sep 2016 02:41 UTCRudy Bolona Expert

Since phosgenite decomposes in water; can acetone or a similar non residue leaving solvent be used as a rinse or will that affect it also?

20th Sep 2016 13:49 UTCTimothy Greenland

Rudy, I have washed my phosgenite specimens in water without any visible harm. I think that the 'slowly' in the warning that it 'slowly decomposes in cold water' means that it should not be left in a toilet cistern or under running water in a stream rather than it cannot stand a quick wash... It is a good idea to dab it dry with clean tissue, then dry with a cold air jet from a hair-dryer, but I have even given one specimen a quick session in an ultrasonic bath without harm... Remember that the original specimens from Bage shaft were exposed to wet conditions for some time before some of them were collected - and they are still phosgenite!

I can see no reason to fear that acetone would damage the specimen, though I have never tried it - but beware of fumes and a fire hazard...

Best wishes

Tim

20th Sep 2016 15:59 UTCRudy Bolona Expert

Thanks for the info Tim.

Cheers!

21st Sep 2016 11:18 UTCPaul Stephen Cyr

I had no idea phosgenite was soluble in water. Huh!

I wonder how all the cove slag phosgenites from Greece have held up over the years...

21st Sep 2016 16:32 UTCRudy Bolona Expert

I read that it is soluble in cold, distilled or fresh water. Probably not salt water as that is one of the factors in its formation. The fresh water leaches out lead chloride from it leaving cerussite behind. There are pseudomorphs of cerussite after phosgenite crystals from Poland.

21st Sep 2016 16:45 UTCAlfredo Petrov Manager

Lead chloride is only slightly soluble in cold water, much more in warm water. Perhaps if you wash the phosgenite fast, in cold water, nothing bad will happen?

21st Sep 2016 19:09 UTCErik Vercammen Expert

Gypsum is also soluble in water, but a quick wash won't harm it.

21st Sep 2016 19:38 UTCAlfredo Petrov Manager

There is a difference between gypsum and phosgenite, Erik: With gypsum itself being slightly soluble in water, you are just removing a very thin surface layer when you wash it; the new surface is still gypsum. But with phosgenite you are decomposing it, not dissolving it; you're leaching out a tiny bit of PbCl2, leaving the Pb carbonate, so a very thin surface layer is not phosgenite anymore but another mineral. I suspect that would dull the luster. Might not be noticeable after a very quick wash in cold water, but I would test it on a crummy piece first before risking an expensive specimen.

21st Sep 2016 19:44 UTCErik Vercammen Expert

Alfredo, thanks for the explanation, I wasn't aware of taht.

Erik Vercammen

21st Sep 2016 20:45 UTCRudy Bolona Expert

All Hail Acetone! It worked like a charm on the phosgenite. With none of the water risk.

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