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Techniques for CollectorsRemoving shale matrix from pyrite?
23rd Jul 2006 19:42 UTCThomas Morrow
I have some pyrite specimens from SE Missouri, USA. They were found in a road cut through a shale layer. The shale seems to be an oil shale (it smells like oil when struck with a hammer). Some of the specimens still have the shale embedded among the crystal terminations. I have been able to flake off most of it with a dental pick but I cannot get it out of the smaller crevices. Does anyone have any tips or tricks to remove the shale and expose the smaller crystals?
Thanks & Regards,
Thomas Morrow
Bentonville, Arkansas
4th Aug 2006 22:01 UTCThomas Morrow
Thought I would post an update. I am making slow but good progress with a heavy duty ultra-sonic cleaner.
Regards.
8th Aug 2006 20:29 UTCWilliam G. Lyon
8th Aug 2006 22:53 UTCThomas Morrow
Regards.
10th Aug 2006 22:43 UTCJohn Makohon
11th Aug 2006 19:45 UTCThomas Morrow
1. The salt solution doesn't seem to affect this particular shale. :(
2. I have tried soaking for up to 2 hours in HCL. This doesn't affect
the shale either. It does remove the tarnish from the pyrite.
3. As part of initial cleaning I have been soaking the specimens in
a solution of dish soap and water and then drying. This seems to help
loosen the shale. I have been repeating this several times.
4. Here is the cleaning regimen I am currently using:
a. Soak specimens in solution of dish soap and water.
b. Dry specimens.
c. Flake off shale with dental pick.
d. Rinse and brush with nylon brush.
e. Repeat steps a-d several times.
f. Ultra sonic cleaner using solution of laundry detergent and water.
I run the cleaner continuously on a timer 30 min. on, 45 min. off to give the transducer a break.
g. When solution gets dirty. Change solution.
h. Dry specimens.
i. Flake off shale with dental pick.
j. Repeat steps f-i until specimen is cleaned.
h. Soak specimens in oxalic acid solution for 30 min. to 1 hour to
remove tarnish.
i. Rinse with water.
j. Nylon brush and clean with soap and water.
k. Brush wet specimen with old toothbrush and whitening toothpaste to
help shine it up.
l. Dry specimen. I now have a sparkly clean piece of pyrite.
This procedure is averaging about 2-3 days. A stronger ultra sonic unit might speed up the process but I am using a fairly heavy duty unit (the 1.5 quart heavy duty model from Harbor Freight). Any additional suggestions,
especially about ultra sonic cleaning solutions would be most welcome.
Thanks and Regards,
Tom
12th Aug 2006 06:02 UTCDon Saathoff Expert
14th Jan 2007 15:21 UTCCharles Brisco
1) Place the pyrite in a small amount of water
2) Freeze
3) Thaw and lightly pick loose shale off.
4) Repeat freeze process as many times as necessary
24th Jan 2007 23:54 UTCAnonymous User
Pyrite is dissolved(as far as I know...)only using Nitric (Azotic) Acid- HNO3.Feel free to use HCL (I think it only cleans the specimen). and try H2SO4-Sulfuric Acid.This awful "monster" solution is very dangerous,so be carefull!I have cleaned Quartz with Pyrite and no (visible) damage done to the Pyrite,and according to my knowledge the Pyrite is not affected Chemically by the Acid.
You'll need a specialist's opinion on what I'm gonna say now,but,probably,the tarnish effect by the HCL is because your speciments have a light film of rust upon them(if so,they should look more golden-red than golden-silver like Pyrite is).If you leave the acid act one day or so 4 water to 1 acid for one day or so,it may clean the rust AND the matrix.Two hours are short tim!
If you have specimens to sacrifce,try Aceton,tooth paste or even Nitro-Cellular Dissolver(you can find these in a wall-paint store).
To be more effective mechanically,use a tooth brush.Use scissors to cut the brush hair and shorten them to half their normal lenth.This will make them less elastic and harder.Fell also free to use a needle,Pyrite Hardness is 6,kitchen knive hardness is 5.5,a needle has to be less,so you don't damage the specimen.
Be careful with these nasty acid and use masks!
-Kostas.
25th Jan 2007 01:37 UTCAlbert Mura
25th Jan 2007 18:02 UTCAnonymous User
Al,are you sure any acid will harm the Pyrite?I've used even HNO3(that is supposed to dissolve the Pyrite)and no damage done(ok,with the Nitric HNO3 I saw some troubles like change in color after a day in the acid,but nothing more.)HCL and H2So4 caused no (visible) damage to my Pyrites.If there is any sign that I could find as a clue my Pyrites are damaged,please let me know(an examination under a loope for example!)
By the ways,yes,I have some Pyrites for trade from Madan,Bulgaria.I will trade for intersting specimens of Quartz(since I'm building this kind of collection right now),but after 2 weeks or so,since now I'm very busy with my exams.Al,please contact me at daus_fr@hotmail.com,if you are interested :)
Cheers!
-Kostas.
25th Jan 2007 20:40 UTCJoseph Freilich
just be careful of what lies underneath the shale...sometimes you dont want exposed what the shale is hiding...
cheers, joe
25th Jan 2007 21:01 UTCAlbert Mura
25th Jan 2007 22:18 UTCAlfredo Petrov Manager
25th Jan 2007 22:31 UTCAlbert Mura
26th Jan 2007 03:18 UTCAnonymous User
May I suppose a solution?First kill any (probably existing)bacteria using Antibiotics,then use a concetrated solution of Sodium Bicarbonate to neutralize any Acid.
Is that right?Could this be done?
Cheers!
-Kostas.
26th Jan 2007 16:51 UTCAlbert Mura
17th Jun 2007 17:08 UTCRock Currier Expert
The solution to your pyrite cleaning problem is not a chemical one. You need to get a sand blaster that is using glass beads and not quartz sand. You will be able to clean your specimens much faster with this technique. I have cleaned thousands of pyrite specimens with air abrasive techniques and it works quickly and well. The pyrites you are cleaning are not very valuable, so you don't even have to exercise much care in their cleaning. Find a metal finishing shop or a shop that has a sand blaster for cleaning sparkplugs and see if you can use one of their sand blasters. You might have to buy some glass beads though and change out their garnet or sand abrasive media for your work, but it will save you many many hours of work.
Rock
20th Nov 2007 21:36 UTCMike Palescuk
24th Jul 2012 18:39 UTCAndrew Zioto
I find these in western new york. Using the method below i have cleaned hundreds of them, and they still look nice and shiny.
What you need:
- 5 gallon bucket
- strainer
- rubber gloves
- face mask
- well ventilated space
- towel you can ruin
- nail brush
- throw away electric toothbrush $5
- Iron out ($14/bottle (dry powder)
- CLR $10-$20/bottle depending on size.
Cleaning method for round nodules of different sizes when you don't want to preserve the matrix:
1) Soak them for a day in water (soften up the shale)
2) Emerge them in a extremely concentrated solution of Iron out. fill a 5 gallon bucket with 3 inches of water and pour in at least 2 cups worth. once you stir it in, the water needs to become clear, or you need more water. soak the nodules in the Iron out for a few hours. Pour them into a strainer. Wearing gloves, cover them in dish soap and massage them together under running warm water. your want them to lightly grind against each other, this will cause most of the shale to fall off and not damage the pyrite. once the soap is all gone, dry them off, and rub each one with a towel (takes time but makes a big difference)
3) Repeat step 2 once more.
4) Soak them in CLR for a few hours. Wash them off good, and than buff with a towel. Shale might still be present in the cracks, if so use the pointy end of a tack to remove it, then soak in CLR again.
Method for cleaning odd shaped nodules when you don't want to preserve the matrix:
1) Soak them for a day in water (soften up the shale)
2) Emerge them in a extremely concentrated solution of Iron out. fill a 5 gallon bucket with 3 inches of water and pour in at least 2 cups worth. once you stir it in, the water needs to become clear, or you need more water. soak the nodules in the Iron out for a few hours.
3) using a nail brush or a electric toothbrush scrub the bejesus out of them to remove the shale, rinse constantly under water to see progress. use the end of a tack to remove shale from cracks/ around the edge of exposed fossils. You will need to repeat step 2 many many times until you have removed the shale.
4) Soak them in CLR for a few hours. Wash them off good, and than buff with a towel.
Method for cleaning pyritized fossils you WANT to leave in the matrix.
1) dip toothbrush in iron out and scrub. rinse briefly under water, dry and repeat, over and over and over. if possible set up your piece in a dish so that only the exposed pyrite is exposed to the iron-out solution, then scrub it every hour or so. change out the iron-out solution ever few hours. Once you have most of the tarnish removed, use CLR on it instead of iron-out.
24th Jul 2012 21:27 UTCRock Currier Expert
24th Jul 2012 21:39 UTCKelly Nash 🌟 Expert
25th Jul 2012 12:59 UTCRock Currier Expert
25th Jul 2012 13:51 UTCRobert Farrar
Bob
25th Jul 2012 14:17 UTCBob Harman
7th Aug 2012 14:00 UTCAndrew Zioto
Andrew, have you tried using a high-pressure water spray gun?
i used my friends and honestly it didn't do much to remove the shale. i tried acetone... nothing (made it feel cold).
iron-out ..... nothing (except the pyrite that i thought was chalcopyrite now looks like regular pyrite)
CLR ..... nothing
The shale containing the 0-1inch nodules is very fractured and splits nice and easily. these nodules clean up nicely with iron-out and CLR.
However, if you go down a few inches, it doesn't have any defining "split" lines. It resembles more of a metaphoric texture and is as dense as Dolostone. I have to use a 12 lb sledge hammer and a pile of wedges to make a dent in it. 1-3 inch nodules and complete fossils in perfect condition make up for the back breaking work required to get them out.
Basically the shale is soooo dense that high pressure sprayers don't do much. Even chemicals like Iron-out are not able to penetrate the shale to much success. I bought some dental picks from a dental supply company in town that really helped ... until i broke them (its that tough).
I'm determined to get these looking awesome. but i feel like i need some restricted-chemical or something that's going to cost a small fortune. Any ideas?
8th Aug 2012 10:09 UTCRock Currier Expert
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