FMF - Friends of Minerals Forum, discussion and message board

[bob kerr]

I bought this from a South African dealer who said he was pretty sure it was malachite after barite on dioptase from the DR Congo. I know malachite after barites were found in Mashamba West but they looked more like barite than these new ones do. Any thoughts?

thanks,
bob

[Kevin Schofield]

[bob kerr]

Yah - here's my tabular barite pseudo after malachite - said to be from Masamba West. Barite comes in numerous crystal forms so the one in question may indeed be as described - but what else could it be?

bob

[Herwig]

To me, the "pseudomorph cluster" does not show enough symmetry to have been an orthorhombic mineral...

[Bob Carnein]

I agree. It looks more like malachite after azurite to me (but, admittedly, I don't remember seeing well developed dioptase with well developed azurite crystals).

[James Catmur]

That was my thought, too

[Riccardo Modanesi]

Hi to everybody!
Nothing to be astonished about! Azurite, malachite and dioptase are all copper minerals, therefore it's not surprising they grow up together! Malachite after baryte? Mmmmhhhh!!!
I would agree with our friends thinking it's malachite after azurite, not after baryte!
Greetings from Italy by Riccardo.

[bob kerr]

Malachite after barite is well known from the nearby Mashamba West Mine - see MR Vol 1 1991 page 16 attached. The article also mentions "rosette cluster shape" pseudos.

Malachite after Azurite is indeed a possibility but azurite is quite rare from this general locality and not mentioned in any article on the region I have read - this doesn't rule it out though.

The second photo above looks definitely like a (green) barite plate/blade. The specimen in question looks more like a rosette and like Herwig said - it does not look orthorhombic - but barite takes many crystal forms.

I'm still not clear as to which is correct - I may just label it as "malachite pseudomorph" and leave it at that.

thanks for the thoughts
bob