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Identity Helpunknown from Etoile, Katanga: please comment

11th Nov 2014 23:02 UTCTony Peterson Expert

FOV about 1.5 mm, what is the bright orange mineral with the malachite? The matrix of the specimen is composed of heterogenite plus specks of this mineral. Purchased on-line so I can't attest to the locality; it is supposed to be "ex-T.S. Bigelow collection". Can't see anything remotely like it in the list of species for this locality.

thanks,

Tony

12th Nov 2014 02:01 UTCTony Peterson Expert

-- moved topic --

12th Nov 2014 02:49 UTCPeter Haas

Is this really malachite ? Morphology doesn't seem right.

12th Nov 2014 03:02 UTCTony Peterson Expert

I would be astonished if it is not malachite Peter, I will be uploading numerous photos in a day or two. It contains mounds of crystals smaller than, but nearly identical to, this specimen:

http://www.mindat.org/photo-82438.html

which makes me wonder if the locale is really Mashamba.

Now you have to take a guess at the orange mineral. I have convinced myself it is NOT colored quartz: the color is very consistent, not like a mixture or a surface stain, and no crystal forms are consistent with quartz. Are there any Co minerals of that color? It is intimately mixed with the heterogenite.

Tony

12th Nov 2014 03:32 UTCWayne Corwin

Tony

It looks like you have 2 diffrent green crystals.

The light green crystals on the right, seem to have diffrent crystal form than the rest of the dark green ones?

12th Nov 2014 04:26 UTCPeter Haas

I see rectangular plates with bevelled edges and stacked aggregates thereof. The plates are easily seen in the lower right part of the photo when you zoom in. May be malachite, but it's not a common habit - and there are other common greens that commonly show similar habits, e.g. brochantite.

12th Nov 2014 14:12 UTCReiner Mielke Expert

It is not quartz because it is too soft? It is malachite because it effervesces in HCl? A few simple tests would go a long way in this case.

12th Nov 2014 16:55 UTCPaul De Bondt Manager

Hi all,

Yes, I see 2 types of green too. Sometimes malachite can be formed from a second generation who have a different color due to impurities in the apport.

Is there some chrysocolla present somewhere on the specimen or another mineral like libethenite or cornetite ?

Is the matrix a kind of soft flat sandstome or more silicified ironstone ?

I think it would be wise waiting for the other pictures before guessing. A picture of the matrix would be helpfull too because some are distinctive to a certain locality but unfortunately not all.

And I can assure you that the specimen shown is from Mashamba West mine. Joseph Lhoest and J.M. Pendeville where at the source when they where found, around 1992.

To be precise, l'Etoile is near Lubumbashi in the south and Mashamba is near Kolwezi, in the north of the Copper Crescent. As I told a while ago, if it's a " recent " specimen, the locality can be anywhere in Katanga because the diggers protect their claim. Labelling them as Katanga would be then the right thing to do. But let's be positive and wait for the pictures.

I hope this helps.

Take care and best regards.

Paul.

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