Cleaning Rough Emeralds

[Nirros]

I recieved a sandwich bag of rough Emeralds from S. America for christmas and was wondering the best way to clean them up. They have quite a bit of outer material on them and although most are pale and milky there are a few that show promise. I am semi new to the gem world so any help is appreciated. i can post a pic if need be but my phone camera is currently on strike

 

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[TeAra]

use room temperature running water and a soft toothbrush with mild soap like hand soap then rinse and dry

 

[Eu_citzen]

Depends on what kind of "outer material" there is, if just clay or other light dirt water will work.

But I guess you've got something else on them, like host rock? Pictures would help.

 

[NHBandit]

Watching this for answers. I have a similar bag of rough emeralds someone brought back from Colombia as a souvenir many years ago.

 

[Nirros]

Its host rock. i have read acid baths but no one will say which acid. I have sulfuric acid and an area + safety equipment for that.

 

[Brian T. Booth]

Its host rock. i have read acid baths but no one will say which acid. I have sulfuric acid and an area + safety equipment for that.

For acids to be used effectively you must determine what rock you are trying to dissolve. If you start putting acid on a rock and don't know its chemical composition you could have a big problem on your hands. If the acid is too strong you could destroy not only the rock but also the mineral you are trying to single out. My best advice to you is to either take the rock to a university and let a geologist determine what type of rock you are dealing with, ask he/she what would be the right coarse of action to single out the preferred mineral. Or I would try to single out the mineral mechanically. Using a hand held rock grinder or maybe a dremel tool. I used a dremel tool to grind away matrix rock around a ruby and had good success.

 

[Nirros]

I will try both....thanks for the advice...I found what appeared to be lead pieces in the bag but my atpro didnt pick up anything....pictures will be added soon

 

[gunsil]

Gotta be careful grinding stone with hand grinders. The resulting dust is very dangerous to breath. Professional lapidary grinders are water fed to keep material and abrasives cool and keep the dust down. Dremels operate at very high RPM and can rapidly heat the material causing discoloration and/or cracking. Professional lapidary equipment runs at low RPM. Most of those bags of Colombian emeralds contain only very low grade stones anyways and usually grinding away the pegmatite host rock will not reveal any gem quality emeralds. Good luck, but be careful.

 

[Nirros]

My father just so happens to have a wet wheel he uses to sharpen chisels....will that work?

 

[Eu_citzen]

Check if the host can be mica schist, which is quite common in some S. American regions. If so it can be carved away with a knife if there isn't to much quartz in there.

Most don't mention the acid to do the extremely hazardous acid you have to use for i.e. mica.
Unless you have a fully equipped lab and the needed training, forget about it.

 

[JohnnyFlake]

Muriatic Acid can be used safely for cleaning gems. It is commonly used to clean cement & mortar residue, bricks, etc.

It can be dangerous! Use in ventilate areas, wear rubber gloves and eye protection. Mix with water to dilute. I suggest starting with a 20% solution and increasing by 10% until you find what works well.

 

[gunsil]

My father just so happens to have a wet wheel he uses to sharpen chisels....will that work?

Emerald is a very hard stone and might cause marks in your father's wheel and make it useless for sharpening chisels. Although the pegmatite host is a bit softer than the emerald I would still be afraid of hurting a wheel for chisels. you could probably find a wheel that is the same size, but made for lapidary work and change out the wheel and it should work fine.

 

[pippinwhitepaws]

emeralds are the most fragile of crystals.
while they test out at a high hardness, they grow in layers...top to bottom...and will split into these tree ring layers with little pressure.

 

[Eu_citzen]

Actually its the healed fractures & inclusions that makes emerald so fragile.
Cracks that healed during formation of the crystal - the healing process in itself produces inclusions.
Of course "newer" cracks are even worse.