FMF - Friends of Minerals Forum, discussion and message board

[Gregor]

I have 5% and 20% acetic acid. If I give it enough time, will one of those substitute for HCI to determine between azurite and linarite ? The blue mineral is adjacent to galena and anglesite in some specimens, in others only the blue crystals are left in vugs. I believe I'm seeing linarite/brochantite, not azurite/malachite but am looking for a positive ID for labels. Thanks

[SteveB]

Positive ID from a word description? You haven’t shown a photo, or provided a location, hardness etc. test results. Generally, you can’t substitute different acids. It's a chemical reaction indicating presence of certain elements. You might get a reaction, but I don't know for certain, and you haven't provided your test results. You’ve provided nothing for anyone to give a positive ID.

[alfredo]

20% acetic acid makes azurite give off bubbles of carbon dioxide, although slowly, not fast like the effervescence under strong HCl. Linarite won't bubble in acetic acid of any strength.

[Gregor]

Great, thank you Alfredo.

[Pete Modreski]

If it's in vugs associated with galena & anglesite, I would guess it's most likely linarite. Let us know what your acid test turns out to show?

[Pete Richards]

I have a note in my catalog describing subjecting linarite to dilute HCl. It did not fizz but dissolved slowly, producing a white coating on the linarite. This was a specimen from the Dunbrack Mine in Nova Scotia, and perhaps it was not linarite (nor azurite).

I just did the test again with a sample of linarite from the Blanchard claims, and got the same result.

So it appears that HCl gives an observable result with each mineral, and the test will be adequate to tell the two apart (as long as the mineral is in fact one of the two).

I suppose the most likely reaction product that would form the white coat would be anglesite, lead sulfate, since linarite is a lead copper sulfate hydroxide.

I would not expect this test to work with acetic acid.