clean remove schist around a mineral

someone know the acid can burn schist around a mineral ?

I use oxalic acid to eat away the mud and gunk and remove the iron oxide staining from the chalcedony I find here. Not sure if that's what you were looking for?
You can find it at Bunnings as Diggers Rust & Stain remover, as it's generally used to remove stains from concretes and stone and as a wood bleach.

Be careful with acids in your arsenal. Often, especially when it's a fragile mineral specimen, it's better to take away surrounding material by hand. Soft brush and lukewarm water first, then introduce soap, then a harder brush if it can handle that. If there's just bits of host rock that need cleaning away I would take a toothpick, or if the mineral can handle it a needle and just scrape away what you don't want.

Oxalic acid is a natural acid, but toxic to humans (and garden pests!). We absorb it through our skin, so gloves are a must when handling oxalic acid. The fumes are quite potent as well, so work outside or in a very well ventilated area. It dissipates quickly, but don't hold your head right over the container when working with it. Safety glasses are a good idea as well, as you may drop your specimen in the solution and it splashes.
When you buy it for specimen cleaning, make sure you get the pure (100% oxalic acid) dry crystals, not a premixed one. Mix it yourself to complete saturation in denatured water (water with no minerals in it that could mess with the intended reaction). Complete saturation is reached when your water doesn't dissolve any more crystals and the excess just sinks to the bottom.

It works better (quicker really) when it's warm. I plce my solution in a black plastic container that sits in the sun. When you first put your specimen in, check it every 15 mins for the first hour, then every hour for the rest of the day. Don't overdo it. You can always place it back in a solution if the results are lacking, but you can't get back what's been eaten up into the solution. You can reuse the solution several times. At some point it gets really brownish-orangy; that's the point where it is fully saturated with minerals and stops working.

Now I've written all this, I don't even know what mineral you are cleaning. Some minerals don't do well with oxalic acid at all.
Here's more info: http://en.wikipedia.org/wiki/Oxalic_acid
http://www.mindat.org/article.php/403/Cleaning+Quartz

Good luck and please show your results!

"I use oxalic acid to eat away the mud and gunk and remove the iron oxide staining from the chalcedony I find here. Not sure if that's what you were looking for?"

Interesting Piep. I just cabbed a small piece of chalcedony - carnelian - even though I knew it was riddled with cracks because it was a nice colour. But now that it is done, I can see that the cracks all through it are full of dirt which is giving the normally bright orange translucent stone a muddy-coloured appearence. I might give it a go.



Cheers

Hey Lefty,

You may want to be cautious with using ox.ac on this cab. The colour may actually dissappear completely as it is caused by iron oxide in the chalcedony. If it's actually in the crystals, you're good, but if it's between them your cab may become a lot lighter in colour.

It's odd, but I still haven't gotten around to actually cutting and polishing any of my found chalcedony, except for a few not so interesting finds from when I just started out collecting. I haven't even shot any pictures of my (now considerable) collection. It just sits there, I look at it, wash it, clean it of crud and compacted mud, wash it again, give it the ox.ac. treatment, wash it again and only occasionally take a piece to the club to saw open, where then for some reason I always end up working on agate or prase that 2 of the old guys have collected in their wild years.

I should really make an effort to at least take some pictures of my finds and the whole cleaning process...

And that cab is a sweet colour indeed!

Cheers Piep. There's no shortage of agate lying around where I find that stuff, it's just that the nice orange-red carnelian can be more difficult to spot than the sard because it often has a layer of brown stone around the agate which makes it look like a million other brown stones. It's only if that agate nodule shape catches my eye that I find it. I'm always hunting for a good bit!

Bits like that seem to be solid orange agate but you reckon that oxalic acid would rip the colour out of the oval one on the left, where it is in the veins and fissures?



Do post some piccies of your collection and the cleaning process, I'd be really interested to see it

HI, thank you Piep for this trick, it is for cleaning emeralds. The schist look like glue and be very hard to clean, it is easy to clean the basic with hot water but some dust are very sticky and thiny ( 0.1mm and less )

for sure I will add some pics before and after ;-)

Lefty said:

Cheers Piep. There's no shortage of agate lying around where I find that stuff, it's just that the nice orange-red carnelian can be more difficult to spot than the sard because it often has a layer of brown stone around the agate which makes it look like a million other brown stones. It's only if that agate nodule shape catches my eye that I find it. I'm always hunting for a good bit!

Bits like that seem to be solid orange agate but you reckon that oxalic acid would rip the colour out of the oval one on the left, where it is in the veins and fissures?

https://farm4.staticflickr.com/3920/14838808054_2d11473c50_c.jpg

Do post some piccies of your collection and the cleaning process, I'd be really interested to see it

Click to expand...

I like those pieces buddy ! I'll swap you something for one of those . I like the one top right ( see my post on tiger/ hawks eye? I'll give you some of that) if keen .

Kingsolomon said:

Lefty said:

Cheers Piep. There's no shortage of agate lying around where I find that stuff, it's just that the nice orange-red carnelian can be more difficult to spot than the sard because it often has a layer of brown stone around the agate which makes it look like a million other brown stones. It's only if that agate nodule shape catches my eye that I find it. I'm always hunting for a good bit!

Bits like that seem to be solid orange agate but you reckon that oxalic acid would rip the colour out of the oval one on the left, where it is in the veins and fissures?

https://farm4.staticflickr.com/3920/14838808054_2d11473c50_c.jpg

Do post some piccies of your collection and the cleaning process, I'd be really interested to see it

Click to expand...

I like those pieces buddy ! I'll swap you something for one of those . I like the one top right ( see my post on tiger/ hawks eye? I'll give you some of that) if keen .

Click to expand...

No worries Barney, I'd be happy to swap for a bit of tiger eye I'll take a couple of more piccies of it first so you can have some idea of the actual size etc.

They are some of my first attempts at cabbing (35 years doing fossicking, less than 6 months doing lapidary ). Most people who have seen them (most people are not fossickers or lapidarists of course) have asked me if they were opal or potch and I guess they do look a bit opalescent. Being an agate they are of course very much harder, tougher and less prone to damage than opal and I reckon a string of the round ones together might make a good bracelet.

The stuff seems to change colour with the light and veiwing angle - in sunlight it often takes on a pale blue-ish reflection. Veiwed through the side it seem more orangey.

You're in Sydney aren't you? I guess I would just send it to you via registered mail. I sent this by registered mail to a mate in Adelaide a few weeks back and he had it in three days.

Couldn't get any better photos of that stone, camera settings seem to have been changed and I can't get them back - thing will only focus on the background.

These are some older photos of the top right stone - the look of it is entirely dependent on the lighting. It seems to look it's best in bright natural sunlight, where it takes on pale blue reflections. Other kinds of lighting seem to diminish the look. Orangey when veiwed through the side. There is a small patch of orange lining a little crystal-filled cavity in the bottom.



The underside.....



Still happy to swap if you still want to, no problems if you change your mind about wanting it though