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Identity HelpEthiopian Opal with strange formation, replacement opal...

27th Sep 2010 05:21 BSTMckenna Praetorius


Have this strange Ethiopian Welo opal with something I've never seen within an opal. It certainly looks organic, like a lichen perhaps. The thing that gets me is how perfectly preserved it is. It looks frozen in time without any sign of decay. Any ideas as to what this is? I know its hard to see in the video but I think it shows accurately that something strange is in there. I've been looking for a paleontologist to help but thus far havn't been able to follow through with any connections I've come across.

Thanks for your time and hope you enjoy the video

27th Sep 2010 13:59 BSTStephanie Martin

Hi McKenna,

This is likely not organic plant material. This appears to be a manganese dendrite inclusion. These are not uncommon in opal. They are often mistaken for fossils in and on other minerals as well. They often form branching formations that are mistaken for plant type fossils. I have a fair amount of dendrite material in my collection and they are beautiful and fascinating.

Now you have something else to research!

enjoy your opal, that one is very nice

stephanie :)

PS - I could take some photos of some of my pieces if you are interested and post them here, but I would need a few days to find time to do them.

27th Sep 2010 18:08 BSTAlfredo Petrov Manager

I'll second what Stephanie wrote: manganese oxide.

28th Sep 2010 00:27 BSTMckenna Praetorius

I know what you mean about being a dendritic inclusion. Here is a link to a neat piece I had of a dendritic inclusion in ethiopian welo opal,

That is clearly dendritic, something I am rather familiar with because it occcurs in so many places, and I agree is beautiful.

This piece is really something else, I can't emphasize how "alive" it looks, fleshy almost, and it reaches through the opal in all directions like it was encapsuled, not on a plane like I often see dendrite form...

I'll try to find a better way to photograph it... I am considering cutting and polishing it, makes me nervouse just thinking about it though

28th Sep 2010 03:40 BSTStephanie Martin

Hi McKenna,

No disrespect but this is not a plant. You have a beautiful opal with dendrites. As indicated these are manganese oxide inclusions and a paleontologist would agree. In the piece shown in the video the inclusions are just more 3 dimensional. These inclusions can apprear as blobs, smears, streaks and branch types and not always just flat or one dimensional. Often they follow internal cracks or faults and other inclusions may seep/bleed in as well, which would explain the change in appearance/colour around the manganese branches.

This material is tricky to work with, it would be best do research on that before you attempt anything. The problem comes with time when the water content is lost, the surface may craze.

Here are 2 pictures of opal with dendrites, these are pictures that were taken previously and all that I have to share at the moment. The dendrites permeate the opal and are not just on a flat plane.

28th Sep 2010 04:07 BSTMckenna Praetorius


I'll take your word for it, but I really still can't believe its dendrite. I have as I've said seen countless samples of dendrite and feel rather familiar with it. This even under a loupe it still looks nothing like dendrite to me, I could be wrong but every time I've seen those formations they form in crystals....

I'll get back to this post after I get more supportive evidence. It really looks like something organic to me, but it is unlike anything I've ever seen before. There is just nothing in me that believes this is dendrite.

28th Sep 2010 04:43 BSTStephanie Martin

If you feel you need another opinion I suggest to take it to your local university (if there is one near you) and have someone there look at it in person. Let us know if it turns out to be something unusual.

good luck,

stephanie :)

21st Oct 2010 17:03 BSTAymeric Longi

Yum, that's a beautifull opal with interesting inclusion or whatever it might be. Some Virgin Valley opals have plant material inclusions, but where formed in different conditions (sedimentary origin) than Ethiopian nodules (volcanic origin). I don't think that a volcanic origin can allow the preservation of some plant material, or any living matter.

21st Oct 2010 21:50 BSTMckenna Praetorius


That very much confuses me as well, Ethiopian opals are of volcanic origin but there have been many examples of replacement opal from Welo. Because of that I do not exactly understand the formation of this opal. Perhaps my understanding of volcanic opal is not accurate in the first place though. Either way Information on the Welo deposit seems rather scarce so far. Gems and Gemology had a good article about it but nothing seemed to cover this matter.

Still no news on this piece either. I did take it to a university but the paleontologist shook her head and said she had no idea what it was, and told me to take it to another college to see if they could help me. That one happens to be a ways away from me so I need to find a time that I can make it out there.

Good point though, and I hope this is awnsered in time. I also found a really neat crystal in the matrix rough from Welo, a very small crystal shaped as a hexagonal dipyramid, could just be quartz but I think it would be worth identifying that as well...

20th Jul 2011 23:18 BSTEthiopia Imports

We have a number of opals in our collection with inclusions that do in fact appear to be organic plant inclusions. These inclusions are different than the ones shown above.

Take a look at this opal. Wello Opal

After the opal was polished and the opal dried, the inclusion can be clearly seen. with inclusion

2nd Jun 2013 10:09 BSTThierry Pradat

I do confirm that these inclusions are of organic origin, not uncommon in Welo opals. The great pict of Ethiopia Import says it all.

2nd Jun 2013 13:56 BSTOwen Lewis

Mckenna Praetorius Wrote:


> Alright,

> I'll take your word for it, but I really still

> can't believe its dendrite. I have as I've said

> seen countless samples of dendrite and feel rather

> familiar with it. This even under a loupe it still

> looks nothing like dendrite to me, I could be

> wrong but every time I've seen those formations

> they form in crystals....

You are used to seeing dendritic growth in a crystal where a dendrite is essentially two-dimensional in nature? But opal is not a crystal but truly an amorphous solid, in which dendritic growth that is three dimensional will be the common form.

Not to say that opal does not carry inclusions of organic origin... I have a small specimen of opal in petrified wood. The case, therefore, that fragments of wood etc. petrify in opal is self-evident.

Get your specimen under a microscope and explore it thoroughly. If you or a local friend can't do this, if you PM me for an postal address, I'll examine and photo it for you in detail. and send it back with pics and an opinion.

8th Dec 2014 23:29 GMTGodfried Sippel

I have a small piece of raw opal. About 3 mm. I made a extreme macrophoto of a part of it. I think it is not dendrite.

( see picture)

Sorry for my bad english

Godfried Sippel

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