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Removing gypsum/selenite from a specimen

Posted by Ron Layton  
Ron Layton March 15, 2012 12:21AM
Is there a safe way to remove gypsum/selenite over growths from mineral specimens other than "club soda" aka carbonated water? I have a few nice Murdochite specimens from the Mex-Tex mine that are covered with gypsum crystals.
Steve Hardinger March 15, 2012 02:43AM
I'm a gypsum collector, so my response may be a bit biased.

Don't remove the gypsum.

I find that the gypsum association is more interesting, and generally more valuable, than the murdochite or gypsum alone.
Rock Currier March 15, 2012 11:49AM
Yes, just place them in water. It helps if the water is moving a little and replaced with fresh water. I know a dealer that gets thousands of some what battered and scratched up Selenite crystals and places them over night in his kids little plastic swimming pool overnight with the water from a hose running a little to keep the water moving and to add fresh water. In the morning they are nicely water polished. I knew another guy who put satin spar gypsum in the little creek near his house and let the creek polish the gypsum. I have removed gypsum from micromount specimens to expose underlying crystals of various kinds with this method. Sometimes it takes a few days and I have to change the water a few times.

Rock Currier
Crystals not pistols.
Ron Layton March 15, 2012 12:27PM
Over a few weeks I have used about 6 liters of club soda and maybe half the gypsum is gone. It was entirely coating the Murdochite/Wulfenite/Plattnerite on Fluorite. I could see these species were present from looking at the edge of the specimen. I'll try the moving water trick. My wife has one of those little fountains that runs continuously.

Edited 1 time(s). Last edit at 03/16/2012 05:31AM by Ron Layton.
Rock Currier March 15, 2012 01:17PM
That should work, until you saturate the water with Calcium. Let us know the result.

Rock Currier
Crystals not pistols.
Steve Hardinger March 15, 2012 04:06PM
Ron Layton April 12, 2012 02:11AM
I put the gypsum under a stream in the wifes fountain and after 4 days and several water changes it is about gone. Just have to keep the water changed so the calcium buildup is kept to a minimum.
Bill Baker Barr April 12, 2012 04:13AM
I once collected at Cheverie on the Bay of Fundy in Nova Scotia. There are outcrops on the beach of anhydrite altering to gypsum. In places there are veins of orange satin spar; when it dissolves away, little bitty blue celestine crystals pop out. The loose gypsum rocks on the shore are nicely water-polished. It's a cool place, highly recommended.

Bill Barr
Canadian-American, eh?
Jolyon & Katya Ralph April 12, 2012 02:36PM
easy way to dissolve gypsum from specimen, put it in the flush tank for your toilet! Also very handy for soaking specimens that have been in acid as you're constantly changing the water without having to remember to. Just remember to take it out after a few days!

Alfredo Petrov April 12, 2012 02:54PM
Whoever gets your flat after you, Jolyon, will probably unwittingly inherit some fine specimens you forgot about :-D
Stephen Rose April 12, 2012 03:18PM
You are a thrifty one, Joylon! You'll save a bit of water with every flush.
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