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  Author   Comment  
Chris Dietze
I stumbled across this website and have been enjoying the various threads. In my youth I was a rockhound and still occasionally collect specimens. I'd appreciate your insight with the following.
I recently aquired a handsome cathedral cut Brazilian geode with amethyst interior. It's about 30" tall, weighs about 120 lb. and the previous owner had it outside at the seashore. It has salt deposits and drifted sand in it, and I'd like to clean it without damaging it. My current thoughts trend toward suspending a metal grid, oven rack or similar, at a comfortable height and placing the geode cut side down on the grid so I can spray a hose up into the geode and wash the crud out. Ideally I'd like to use a surfactant but don't want to leave any residue on the crystals.
Any ideas would be appreciated!
Mike Streeter

Your plan sounds like a good one - I say go with it and let us know how it turns out!

Hi Chris

Add vinegar to your final rinse, it will help dissolve any remaining salt residue, and should leave a shine on the amethyst.

It is most likely crystallized salt that is causing the sand to stick to the amethyst crystals so plain old water should dissolve the salt and release the sand.Warm water might help so long as the water's temperature is started at the ambient temperature and warmed up slowly so as not to shatter the crystals.Some of those amethyst cathedrals have calcites in them so the vinegar being an acid might damage them.It won't hurt the quartz/amethyst,but if there are any calcites(usually clear to white) I would see how the plain water works first.
I have some Brazilian amethyst pieces and I clean them a couple of times a year for about an hour in a couple of gallons of room temperature water with a cup or so of bleach in it.I then rinse them and place them for a few minutes in a solution of 2 gallons of water with a cup of ammonia in it to remove any bleach smell and/or residue.
Chris Dietze
Thanks for your replies! This geode does have a calcitic cluster in it so I'm cautious about using even mild acids as I recall damaging a nice calcite I had found in a quarry by trying a low molar content hydrochloric rinse.
I expect to get a chance to try rinsing it out this week, and I'll let you know what happens. My wife is a conservator and she suggests a bit of ammonia. I'll try just H2O first.
Don Peck
I agree with your wife's advice. Ammonia will not attack the calcite and should leave a great shine on the quartz.
Chris Dietze
Today I had some time in the afternoon, so I carefully cleaned the geode with a weak solution of Mr. Clean and water. It seems to have left no residue and I've successfully removed the sand and salt. The geode is still face down drying on a wicker rack. When I get it set up in the house I'll post a pic if anyone would like to see it. It has impurities I've tentatively identified as manganese which create gold and copper colored flecks in the light colored amethyst crystals.
Just saw your post.
I have a 30 kg Amethyst geode who has a lot of dust in it, and wondered what would be the best method getting the dust out... and gtet the spikes to shine...
Doing one by one with a damp cloth will take me days I think....[frown]

I am just not sure if I cn safely turn it upside down as you described.....
looking forward for your experience...[smile]
Bob Harman
Before I get directly to the cleaning process that I might use, I will make a few assumptions.

Your example probably is from Brazil or Uruguay.    It is the "usual" amethyst cathedral with no delicate areas or other minerals on the amethyst. The example can be turned on its side and then be shaped like a large bowl, capable of holding water. And finally, what you describe as "dust", is truly just dust and not a "crust".    

If my assumptions are correct, here is how I would clean it. Amethyst variety of quartz is a stout mineral, easily cleaned.     Take your example outside or put it into a large laundry sink.   Turn it on its side and fill it with water with some household vinegar added. With a simple rag, wipe the crystals with the wet rag.    Follow up with a complete rinse in the sink or outside with a garden hose.   Let all the water drain out and then let dry. The crystals and crystal tips should be shiny when dry.

If my assumptions were not correct, we will have to start over for your individual example.   BOB
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