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GeneralSolubility of some Cu minerals

6th Jun 2012 05:11 UTCAnonymous User

Hello everyone.

I would like to be able to indentify some Cu minerals with the solubility test, but I can't find the information about that.

I try find a reliable sourse of information about the solubility in H2O and HCl for the following minerals:

Malachite, Brochantite, Antlerite, Atacamite, Chrysocolla, Azurite, Chalcanthite

I would apreciate all the answers you could provide me with.

Thank you.

6th Jun 2012 14:38 UTCDonald Peck

Solubility of copper minerals:

Malachite: any mineral acid (including HCl)

Brochantite: any mineral acid

Antlerite: HCl, H₂SO₄

Atacamite: any mineral acid

Chrysocolla: insoluble

Azurite: any mineral acid, slightly soluble in H₂O

Chalcanthite: H₂O

8th Jun 2012 17:56 UTCStephen Moreton Expert

Of all these only chalcanthite will dissolve in water. All will dissolve in HCl, or other mineral acids like H2SO4 and HNO3. Chrysocolla will dissolve too, but may leave a gelatinous residue of silica gel in the process. Malachite and azurite will effervesce as they dissolve, the others will not. The best mineral acid to use is dilute nitric acid as then one is free to test the solution for chloride and sulphate.

8th Jun 2012 20:53 UTCAnonymous User

Thank you a lot for your answers.

Given that I need the tests for field work (not lab): How can I tell the difference between Atacamite, Brochantite and Anthlerite?

Is there any difference in the cinetics of the dissolution in HCl that I could notice? Any other test for field work?

9th Jun 2012 09:56 UTCStephen Moreton Expert

If you use dilute nitric acid then you can test the solution for sulphate (with barium chloride) and chloride (with silver nitrate). Obviously do the chloride test on a solution that has not just had barium chloride added to test for sulphate! Bear in mind that atacamite has polymorphs clinoatacamite, paratacamite and botallackite. It would take XRD or IR to differentiate these, and they may occur mixed together. Brochantite and antlerite are also similar, and would need XRD or IR to tell apart. But brochantite is much more common, antlerite tends to occur in more acidic environments. Of course there are other basic copper sulphate minerals, like langite, wroewolfeite and posnjackite, which will give the same chemical reactions, although they tend to be more blue/green in my experience than brochantite, which is green. You might even find connellite, which has both chloride and sulphate. It is deep blue and quite distinctive. They will all dissolve, easily, in mineral acids.

9th Jun 2012 14:34 UTCReiner Mielke Expert

You may be able to differentiate the chlorides from sulphates with KOH solution. It is supposed to alter Atacamite to cupric oxide (Dana). Haven't tried it myself. Other than that, I know of no way of distinguishing them in the field ( without doing lab work first) other than to differentiate between a carbonate such as malachite and something else with HCl.

9th Jun 2012 17:10 UTCDonald Peck

Velin, Stephen gave you the simplest and easiest ways to test for the minerals. But I am not sure if it works well in the field. You would need to carry a small laboratory with you. At a minimum, a half dozen semimicrro test tubes or a couple of very small pyrex beakers, some source of heat. stirring rod, a clamp to hold them when you are heating them, and plastic dropper bottles of nitric acid, distilled water, silver nitrate, and barium chloride.

5th Dec 2012 06:22 UTCJuan Zhao

I want to know the solubility of Chrysocolla.If you have known its solubility,please tell me as soon as possible.Thank you!

5th Dec 2012 06:34 UTCJuan Zhao

I Synthesis of a substance,but how to prove that it is chrysocolla.I have take XRD and IR to detect it,but the effection is not good.I hope that I can get some suggestion from you.Thank you!

5th Dec 2012 14:51 UTCEvan Johnson

I would say that synthetic chrysocolla would have to be determined via something other than field tests.

5th Dec 2012 14:52 UTCEvan Johnson

E.g. I could probably make a reasonable sol-gel "chrysocolla" with copper sulphate and sodium silicate.

8th Dec 2012 14:47 UTCAnonymous User

Chrysocolla can be diferentiated in the field with it's charasteristic color+it isticks to your tongue (similar to fresh volcanic ash).

I don't know if this is of any help.

By the way, thanks for all the answers.

You have been all of a lot of help.

11th Dec 2012 16:33 UTCFritz

I am looking for a data base for copper sulfate such as brochantite, devilline, posnjakite and other copper mineral such as chrysocolla and atacamite.

Is there a data base accessible for these minerals? Does somebody have it?

Thanks!

Fred

24th Jan 2013 19:24 UTCJavier Lavin

Hello Everyone,

I need special help, I need Kps (solubility constan) to brochantite (Cu4SO4 (OH)4), any can help me.

best regards,

Javier Lavin

25th Jan 2013 17:48 UTCDonald Peck

Javier, If there is a college nearby, or a good public library, they may have the Handbook of Chemistry. The Ksp you are looking for probably is in there. I could not find the value online and I no longer have a copy of the Handbook.

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