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GeneralFor the Love of Dendrites

19th Aug 2012 08:17 UTCStephanie Martin

Hi All,

This thread is being dedicated to the lovely form of dendrites. Initially this began as an appreciation of manganese oxides, however I invite any kind of dendrites to be shared here. In addition since dendrites are well suited for lapidary purposes and are poplular as such, these are also welcomed to be shared here.

Here are a few to start the parade. I left out Solnhofen deliberately since I am sure many of you would have wonderful ones to contribute and I would love to see them.

This first one is from Utah, USA, if anyone knows a more specific location please let me know.

Approx 10 x 9 cm

Rockydale Quarry

Roanoke, Virginia, USA

label indicates collected 7/11/1996

6 x 4 cm



Ontario, Canada

6 x 2cm


19th Aug 2012 08:23 UTCStephanie Martin

A few more...

Dřínová, Tišnov, Moravia, Czech Republic

Czech Republic

7.8 x 5.5 cm

Some lapidary items...

Cuprite Dendrites in Pectolite (larimar)

Dominican Republic

2 x 2 cm


Dendrites in Chrysocolla with Malachite

location unknown

18 mm x 14 mm


19th Aug 2012 11:14 UTCRoberto Bosi

Nice idea, Stephanie. Here are two specimens from Solnhofen. The first, as regards of the dendrites, is not exceptional but agreeable; a single, isolated, well defined and almost symmetric "branch". This is an occasion, however, to show a very nice Saccocoma pectinata (on the left), a probable larval crinoid typical of this place. Its diameter is 26 mm.

The second specimen is an ammonite (diameter 30 mm) crossed by well defined dendrites. I hope you like it.

19th Aug 2012 11:35 UTCRock Currier Expert


Why don't you write an article about dendrites? At the very least you should write up a better definition for our glossary than the one we have and show some more pictures of them.

19th Aug 2012 12:46 UTCAgustin Agudo Espinosa

I bring a bit more to the fantastic world of the dendrites

I think for many, was the first samples, we began to captivate.

Here is a copy of manganese oxides from Jalapa Mine in El Molar, Tarragona, Catalonia, Spain.

Greetings to all.

Agustin Agudo Espinosa.

19th Aug 2012 13:43 UTCRui Nunes 🌟 Expert

... and some manganese dendrites from Portugal. Greetings, RN


19th Aug 2012 15:19 UTCKelly Nash 🌟 Expert

Beautiful examples and great topic! I hesitate to put this here because I am of course quite dubious that it's authentic. It appeared in Mineral Digest (vol. 5, Winter 1973) in an article by Roger Caillois, and well, it's interesting. The caption said it is limestone and the source is unknown and there was nothing else about it in the text. I'm curious if anyone has seen this piece and knows anything more about it.,17,file=40084,filename=Dendrites-sml.jpg

19th Aug 2012 15:59 UTCNorman King 🌟 Expert

This appears to be a dendrite of hematite. Perhaps it is hematite after a Mn oxide, but the rim of normal-appearing Mn dendrites around the hematite suggests the hematite was original. This was found at a fossil quarry in shale of the Middle Cambrian Wheeler Formation, House Range, Millard Co., Utah. There are trilobites on bedding surfaces in this piece.

19th Aug 2012 16:48 UTCDennis Tryon

Steins Pass, New Mexico, north side of I-10, self-collected.

19th Aug 2012 17:36 UTCStephanie Martin

Great stuff everyone! Glad to see there is interest. Kelly, that piece would definitley require more investigation.

Rock, I will eventually put together an article, would like to see what interesting things may turn up on this thread in the meantime.


stephanie :-)

19th Aug 2012 18:12 UTCAgustin Agudo Espinosa

Now an example of the Canary Islands, dendrites of manganese oxides, found on the road near the village of Toto on the island of Fuerteventura (basal complex).

A.Agudo Espinosa.

19th Aug 2012 18:35 UTCRui Nunes 🌟 Expert


I bet 99,99 % that this is not a dendrite neither a limestone specimen. It seems man made something like a drawing inspired in a limestone landscape and in the dendrites effects. Buildings, people, trees, birds, all in the right place... not natural for me.


19th Aug 2012 20:29 UTCJohn Montgomery 🌟 Expert

Glad to hear that Stephanie...I look forward to reading that article as I have no idea what these beautiful specimens are or how they came about etc....thanks


19th Aug 2012 20:41 UTCAntónio Manuel Ináçio Martins

Hi Sthephanie :-)

Some Dendrites of my collection :


Martins da Pedra

19th Aug 2012 21:14 UTCDean Allum Expert

Rui, Those are magnificent. Could you please post more pictures from your collection?

Stephanie, do these fit the definition of mimetoliths?

While I don't have any worthy manganese dendrites, this fluorite pattern is reminiscent of dendrites.

-Dean Allum

19th Aug 2012 21:41 UTCStephanie Martin

Thanks all for the continued contributions, hope everyone is enjoying them as much as I am.

Dean, I would assume that they would qualify because they do resemble trees or ferns or such. And I do believe you have a worthy example of dendrites, and the spodumene they have formed on makes a nice contrastive canvas.


stephanie :-)

19th Aug 2012 21:55 UTCRui Nunes 🌟 Expert

Hi Dean Allum. thanks for your comments... more three pics. Cheers



20th Aug 2012 00:38 UTCDan R. Lynch

Don't forget about dendrites within/on agates. Here's one of my favorites: my dad had a junk Lake Superior agate, showing no banding or any other redeeming features. Tossing it into a bucket, it broke along its banding (which we call "peeling," as this typically occurs due to freeze/thaw cycles). Examining the two halves that had popped apart, I noticed this tiny 1cm dendrite hiding on the surface, where it had been formed in the microscopic space between the bands.

20th Aug 2012 03:28 UTCMarc Miterman (2)

Wow, What a great thread !

I have always loved Dendrites.

This specimen has been in my collection since 1971.

Pyrolusite Dendrite

Eichstatt, West Germany

16 cm x 9 cm

20th Aug 2012 11:55 UTCTom Goodland

Hi everyone,

I recently found some calcite crystals with distinct presumably manganese oxide dendritic growths on several of the crystal faces. I have found similar dendritic growths from several different locations, where they had been caused by solutions seeping between bedding planes, but i'm mystified how these particular dendrites could have formed. Has anyone else seen dendrites on crystal faces?

Sorry no photos at present, all my specimens are in storage.


tom goodland

20th Aug 2012 15:43 UTCBoris Erjavc


here are some of calcites with probably manganeze dendrites on crystal faces.

Mežica Mine,Slovenia:

Back side, same specimen:

Jasovnik tunnel, Slovenia. 3 × 3.5 × 3 cm

Specimen was all embeded in clay.

Good luck


20th Aug 2012 17:29 UTCRob Woodside 🌟 Manager

Dendrites loved and lost.

Alberoda Silver

Santa Rita Copper

20th Aug 2012 18:52 UTCRock Currier Expert

The Mineral Digest was created by Julio Tangelof sp? who ran a company called Astros back in the 70s in New York City. He was notorious for never paying his bills and selling Mexican coconut geodes that cost $5 anywhere else but he was selling them for $60. His sales people often didn't know what they were selling and I doubt that he could identify more than 20 common minerals by sight.. The people he hired to run his organization knew even less. He was an egomaniac of the first order. The magazine was designed as an advertising vehicle and for his personal aggrandizement which shines through loud and clear if you read some of the articles that he paid a captive editor to have written about him and his wife by hacks. I should add that this is my personal point of view and that his descendants still run the business out of NY City today and might have an entirely different point of view.

20th Aug 2012 19:15 UTCStephanie Martin

Thanks for the info Rock. Given that information we could discern that there is likely not much credibility/validity behind the publication regarding the piece that Kelly posted. I agree with Rui, it has too many things in the correct order.

Rob, you say you "lost" those, I hope they went to good homes. Thanks for sharing your mementos.

20th Aug 2012 19:38 UTCRob Woodside 🌟 Manager

The Copper is on display at the Royal Ontario Museum and maybe the Gold is too. The Silver is in the dungeon there.

21st Aug 2012 01:44 UTCRaúl Jorge Tauber Larry

Microphoto of Manganese Dendrites on Aragonite.

FOV: 4 x 4 mm.

From "Puesto Viejo" Quarry, Sierra de Puesto Viejo, Santa Bárbara Department, Province of Jujuy, Argentina.

Collected in 2004.

21st Aug 2012 01:54 UTCRaúl Jorge Tauber Larry

Manganes dendrites on mud-clay.

Specimen size: 12,7 x 9 x 1.8 cm.

From Raco River, Trancas Department, Province of Tucumán, Argentina.

Collected in 2010.

21st Aug 2012 01:57 UTCRaúl Jorge Tauber Larry

Manganese Dendrites on Clay-Shale.

Specimen size: 6.7 x 4 x 2.1 cm.

From Salar del Hombre Muerto, Antofagasta de la Sierra Department, Province of Catamarca, Argentina.

Collected in 2002.

21st Aug 2012 02:00 UTCRaúl Jorge Tauber Larry

Manganese Dendrites on mud-clay.

Specimen size: 7 x 4 x 2,3 cm.

From "Loro" River, Burruyacú Department, Province of Tucumán, Argentina.

Collected in 80´s.

21st Aug 2012 02:04 UTCRaúl Jorge Tauber Larry

Dendritic manganese oxides on schist.

Specimen size: 19.5 x 11 x 0.5 cm.

From Salar del Hombre Muerto, Antofagasta de la Sierra Department, Province of Catamarca, Argentina.

Collected in 2004.

21st Aug 2012 03:59 UTCStephanie Martin

Raul ~ Wonderful pieces. Nice to see from Argentina!

Tom - regarding growth on crystals, I think it depends on the type of crystal and the environment in which the dendrites form. Dendrites are seen frequently on feldspars and I think it might have to do with the actual surface of the crystal. Certainly they seem to like more porous surfaces, perhaps that is a coincidence based on the nature of the deposits where they are more typically found. But you are are right, you don't see them much on gem type crystals, more in them than on them, especially quartz. I suspect this might have to do with secondary deposition conditions and these don't seem to favour them forming and adhering to gem crystals in their environs.

Here is a feldspar with some incipient dendrites in what I call the blotchy stage.

Orthoclase twin

Cinco, Kern Co, California USA

4 x 2.5cm ex Fred Devito

21st Aug 2012 04:16 UTCStephanie Martin

Dan, yes agates, jaspers, opals et all are definitely welcome. I really don't know where to start! I am hoping that others will share such natural art.

There has been a lot of this Chinese jasper out there, they look so much like paintings, so I had to get one of course. 10 x 4cm.

And the great thing is that it has two sides that can both be displayed, which side to choose? Or should I get one of those spinning frames? LOL.



stephanie :))

21st Aug 2012 05:28 UTCStephanie Martin

Sorry I don't have many details on this one such as age and species (I suppose I could look it up but nah, too lazy), I bought it for the dendrites. Imagine that. Oh, I should have warned you... I love dendrites. :-D

Fossil Clam


4.3 x 2.8cm

21st Aug 2012 07:44 UTCCorie Mattar

All these specimens are fantastic, I really find myself liking the white with black dendrites from Portugal, very striking!

Here is a lemon opal dendrite from the Knoxville Recreation Area north of Napa California.

25th Aug 2012 17:51 UTCStephanie Martin

Dendritic Copper

Colonial Mine

Cape D'Or, Cumberland Co, Nova Scotia, Canada


Aborescent Silver coated with Safflorite

Millerette Mine, Haultain Township, Gowganda area, Cobalt-Gowganda region, Timiskaming District, Ontario, Canada



26th Aug 2012 02:32 UTCRaúl Jorge Tauber Larry

Dendrites of Mossy Agate

FOV: 10 x 5 mm.

From Madagascar.

26th Aug 2012 02:56 UTCRaúl Jorge Tauber Larry

Beautiful dendritic massive specimen of Native Copper with Quartz Cystals included.

Specimen size: 9.5 x 9 x 4.6 cm.

From Copiapó, Copiapó Province, Atacama Region, Chile.

Collected in 1996.

26th Aug 2012 02:58 UTCRaúl Jorge Tauber Larry

Beautiful dendritic massive specimen of Native Copper with Quartz Cystals included.

Specimen size: 10.5 x 6.5 x 6 cm.

From Copiapó, Copiapó Province, Atacama Region, Chile.

Collected in 1996.

26th Aug 2012 03:01 UTCRaúl Jorge Tauber Larry

Very nice sample of Dendritic Native Copper with flattened crystals and Malachite covered.

Specimen size: 5.6 x 2 x 1.1 cm.

From Osceola Shaft # 10, Calumet, Houghton County, Michigan, U.S.A.

26th Aug 2012 03:11 UTCRaúl Jorge Tauber Larry

Beatiful Dendritic Psilomelane. It looks as branches of tree.

Specimen size: 7.5 x 6 x 4.5 cm.

From La Providencia Mine, Susques Department, Province of Jujuy, Argentina.

Collected in 60´s.

26th Aug 2012 06:55 UTCStephanie Martin

Very nice Raul, thanks for sharing. I really like the psilomelane.

Here are some cryptomelanes. I have posted these before but couldn't resist posting again for the dendrite cause.


Pitorra mine, Galiléia, Minas Gerais, Brazil

Longest dendrite 28mm

faceted stone is 15mm x 10mm (unknown dendrite type), Brazil

26th Aug 2012 07:02 UTCStephanie Martin

It's about time for some dendritic opals...

Moss Opal

Nasławice, Gogołów-Jordanów Massif, Lower Silesia (Dolnośląskie), Poland

~4.5 x 4.5cm

The next two are from the same location, Czech Republic.

Bohouskovice, České Budějovice (Budweis), South Bohemia Region, Bohemia (Böhmen; Boehmen), Czech Republic

3.0 x 1.5 cm


2.0 x 1.5 cm


26th Aug 2012 14:05 UTCjulie g. powell

Stephanie Your sample looks like many I have seen at the Iron mines around

cedar City Iron county ,Utah Check out Dave Crosby site for maps and locations. I have been looking for dendrites in agate ( good one) in the east hills around Summitt Utah A very large area for agate, it goes all the way up the mountain to Brian Head Happy Hunting/size>

26th Aug 2012 14:08 UTCjulie g. powell

Stephanie Your sample looks like many I have seen at the Iron mines around

cedar City Iron county ,Utah Check out Dave Crosby site for maps and locations. I have been looking for dendrites in agate ( good one) in the east hills around Summitt Utah A very large area for agate, it goes all the way up the mountain to Brian Head Happy Hunting/size>

26th Aug 2012 15:48 UTCBart Cannon

I want to grow my own manganese oxide dendrites.

They seem to be natural fractals, and I have a hunch that they grow quickly and, as Bacteria Bart, I think there is an organic aspect to their formations, but I have never heard of mangenese metabolizing bacteria.

I tried an experiment. I crushed up some dirty manganese oxides, emusled them in rainwater, moistened some microscope slides in the suspension and waited almost a year for something to happen. Nothing happened.

It seems as though they most commonly form in fractures in carbonate rocks. I wonder it those carbonate rocks are most often manganese bearing.

My next effort will be to create some little slabs of manganese bearing carbonate rock, join them, and put them in dirty rainwater and leave them alone for at least a year.

Are there non manganese oxide examples of dendrites ?



26th Aug 2012 16:09 UTCStephanie Martin

Bart - an important factor in the growth of dendrites is surface tension, that's why I don't think they grew on your slide, or why they don't grow on many well developed gemmy crystals. The surfaces do not have enough "gription". There are a number of factors hat have to be just right for them to grow and it is my observation that porous rocks such as carbonates are a better host. These are usually sedimentary in nature, or weathered granitic formations where the environmental conditions exist suited for the growth of dendrites. There may be an organic component which is being studied. Yes, there are other dendrites besides manganese oxides, iron oxides would probably be the next most common.

And yes, they are natural fractals.

26th Aug 2012 17:20 UTCBart Cannon

Thank you Stephanie,

I can't tell if your cryptomelanes are beautiful or creepy. I'll stick with fascinating.

I have an intuition that dendrites form by capillary activity (wicking).

My next experiment in growing my own dendrites will be to split some fine grained carbonate rocks and bind the pieces back together rather than ginding and mating some small slabs. That should improve the "gription" and improve my chances of becoming the first dendrite artist. A goal with no practical value. My specialty.

Maybe I'll use some weak manganese sulfate solution with the rainwater.


26th Aug 2012 23:09 UTCAlex Homenuke 🌟 Expert

Re: "a goal with no practical value" - I don't know about that, Bart. The psychologists could use them for Rorzhak (sp) tests.

27th Aug 2012 03:24 UTCBart Cannon


That's very funny, i retract my statement about no practical value for dendrites..

A completely natural and random source for Rorschack images.

I will would work on Rorschack pairs during first day of retirement. Except that would be a day after I'm dead.

I don't know how to spell that guy's name either.

I seem to think that Ruggles Mine uraninite, gummite specimens show a dendritic nature.

The difference between dendritic and arborescent features would seem to be two dimensions vs. three dimensions.


27th Aug 2012 04:07 UTCStephanie Martin

Bart you are right about the uraninites from Ruggles, also some triphylite from the same area shows this as well. I'll post some eventually :))

Wicking may be a factor in the creation of surface dendrites as per your instinctual hunch.

And FYI the correct spelling is Rorschach. I would think that inkblots are essentially fractals as well.

27th Aug 2012 11:40 UTCMaggie Wilson Expert

Bart Cannon Wrote:




> The difference between dendritic and arborescent

> features would seem to be two dimensions vs. three

> dimensions.


> Bart

a-HA! - Answers a question that I've been pondering since the start of this thread - thanks, Bart!


28th Aug 2012 14:33 UTCMaggie Wilson Expert

The Handbook of Mineralogy describes the crystal habit of berzelianite as "thin dendritic crusts"

Dendrites, eh? Ok, here we go! The display face of this specimen has been cut and polished to show off the dentritic effect.

29th Aug 2012 03:35 UTCStephanie Martin

Maggie that berzelianite is really cool polished like that. Striking piece!

Well it seems I keep finding those dendrite things turning up everywhere. :-D

Here's another featuring arborescent copper in gypsum.

Mission complex, San Xavier, Pima District (Olive District; Mineral Hill District; Twin Buttes District), Sierrita Mts, Pima Co., Arizona, USA

FOV 1.5 cm

29th Aug 2012 07:07 UTCRick Dalrymple Expert

I have always loved dendtrites. I started gathering them up but quickly over ran my daughter with things to photograph.

Here are a few...


29th Aug 2012 13:16 UTCMaggie Wilson Expert

These arborescent silver crystals are covered in micro safflorite crystals - leaves of silver for accent.

I love the structural aspect of these specimens and they LOVE to be photographed.

Castle Mine

Cobalt-Gowganda region, Ontario, Canada

2.6 x 2.0 x 0.8 cm

29th Aug 2012 15:47 UTCRick Dalrymple Expert


29th Aug 2012 15:56 UTCAlexis Monnerot

Manganese oxyde dendrites self-collected, from Argentinia.

30th Aug 2012 19:42 UTCRick Dalrymple Expert


30th Aug 2012 20:34 UTCRick Dalrymple Expert

These malachite dendrites are very prolific at the mine. They are on sandstone and are about a thick as a hair, maybe thinner.

31st Aug 2012 11:59 UTCMaggie Wilson Expert

Here's a local one for you Steph - a thumbnail of manganese oxides from the DeForest Quarry, near Inglewood, Ontario.

31st Aug 2012 14:10 UTCClifford Trebilcock

Hi Steph,

Here is a photo of some Dendrites in translucent Quartz I collected from an unnamed Feldspar prospect in Center Minot,Maine.

It is about 9 X 6 CM in size and the Dendrites are both on the surface and along internal fractures. Many great photos of Dendrites on this thread.


1st Sep 2012 06:21 UTCStephanie Martin

Nice to see all the great contributions! Alexis that is a lovely find, definitely a keeper.

Rick - thanks for sharing so many, you made my day.

Maggie – a nice local surpise, and from a location that is usually known for orange celestite. Just wonderful!

Cliff, that is a stunning unspoiled dendritic quartz! Hope you plan to keep it that way!

More on opals. You often see this material used for cabachons, pendants, earrings etc, but I just find the centers are fascinating on these dendritic opal nodules from Turkey. The chalcedony layer adds some interesting contrast and is fluorescent.

Eskişehir Province, Central Anatolia Region, Turkey

7 x 5 cm and 5.5 cm

1st Sep 2012 20:03 UTCJohn M Stolz Expert


Hey Steph, whaddya think of this one?

Regards, John

1st Sep 2012 23:30 UTCDean Allum Expert

Wow John,

That's a beautiful specimen! It's good to see that you have finally developed an appreciation for mineralogy and some healthy curiosity.

Unless you have just illegally posted a copyrighted picture which you do not own. THEN SHAME ON YOU!! :-X

2nd Sep 2012 06:56 UTCStephanie Martin

John, a stunning lilac spodumene adorned with dendrites! I can't take my eyes away from it! I've spent more than 5 minutes trying to think of something positive to say to you for cheating by posting my photo. There's an old cliché about imitation being the highest form of flattery. Nice try, but you need to get your own dendrites! :-X


2nd Sep 2012 11:02 UTCJohn M Stolz Expert


I think you're confusing "appreciation" with "aesthetics". I actually have both. What I seem to be missing is good judgement.


Apologies; it didn't occur to me that I would cheat you by posting your picture. 4 pages of posts went by and I never saw it. I was under the impression that this was all about knowledge for knowledge's sake.

To both of you,

1. There was no intention on my part of claiming "credit" for a photo that doesn't belong to me. Hover your mouse over the picture and see what you see,

2. There's always a danger with the written form of communication for miscommunication to occur. For my part, I apologize for having taken the liberty of assuming you would find my clownish actions amusing and in good spirit, instead of insulting. You can be assured I won't take such liberties in the future. Especially now that it seems clear that all I'm doing is making an idiot of myself by having to post a public apology.

2nd Sep 2012 15:20 UTCRaúl Jorge Tauber Larry

Manganese Dendrites on Feldspar(Albite-Anorthite Series).

FOV: 5 x 4 mm.

From Pegmatite of Milagro Mine, Cerro Pichao, Sierra de Quilmes, Tafí del Valle Department, Province of Tucumán, Argentina.

Collected in 1973.

FOV: 5 x 5 mm.

2nd Sep 2012 17:01 UTCRaúl Jorge Tauber Larry

Manganese oxides dendrites on feldspar(Albite-Anorthite Series).

From pegmatite of "Milagro" Mine, Cerro Pichao, Sierra de Quilmes, Tafí del Valle Department, Province of Tucumán, Argentina.

FOV: 4 x 5 mm.

2nd Sep 2012 17:56 UTCStephanie Martin

John, I was actually rather amused that you posted my photo. But I couldn't resist the return barb. And actually I imitated you as well, by using words from your original post. So I guess you didn't pick up on that, but as you said the written word can sometimes be difficult to impart nuances.

Regarding the specimen, I was going to get around to it posting it again eventually, but it was nice to see it. I have enough dendrite material to post one everyday for the remainder of the year if I wanted to, but will spare you all from that overkill. LOL.

Let's get back to dendrites!


stephanie :-)

2nd Sep 2012 19:35 UTCStephanie Martin

Maggie, here is another from Ontario, but alas there was no other locality information with it.

Dendrites on Feldspar, Ontario, Canada

approximately 6 x 6 cm

2nd Sep 2012 22:57 UTCRoger Curry

Hi all,

just got back from West Cork, Ireland. Went looking for arsenopyrite crystals. Also saw this bit of sandstone, which I left in-situ at the dumps of
Dhurode (Carrigacat) Mine.



7th Sep 2012 05:24 UTCStephanie Martin

Roger, thanks for posting that in situ photo. I appreciate that you took the time to notice it there and snap the pic. I was hoping to see dendrites from uncommon places, and you measured up to that expectation nicely. Hope you were able to find some arsenopyrite too.

Today a little piece of jasper-like material known as opalite from Australia. The information I have says it is found in the opalite mines not far from the Yerilla Chrysoprase Mines in the Goldfield Esperance region, Western Australia.


3 x 2 cm

7th Sep 2012 23:13 UTCRoger Curry

I was successful in my primary objective Stephanie, but as soon as I saw the dendrites, it brought back memories of one of my first collecting trips, when I found some lovely manganese dendrites on a slab of magnesian limestone at Sunderland. Some 40 odd years later, I also remembered this thread, so the photo. Here's dendrite formation (NASA)



8th Sep 2012 17:18 UTCRob Woodside 🌟 Manager

Thanks Roger, Is that growing in micro gravity? The horizontal growth is faster than the vertical in the photo.

8th Sep 2012 17:40 UTCStephanie Martin

Rob, I think this link explains it. This is usually a result of heat and cooling rates.


stephanie :-)

8th Sep 2012 17:56 UTCRob Woodside 🌟 Manager

Thanks Stephanie, but I think Roger has a different specimen. His has both horizontal arms. In microgravity the growth should be the same in all symmetrically equivalent directions. Flames are spherical until the local oxygen is exhausted. So maybe I've answered my own question since the vertical growth is not as fast as the horizontal. Cool pictures, Thanks.

8th Sep 2012 18:01 UTCStephanie Martin

Yes, that's what I was getting at. If it was in micro-gravity, the growth should be symmetrical. I agree, It is a great little gif.

8th Sep 2012 20:25 UTCIan Jones Expert

One from Cornwall, where most good things come from:-).

8th Sep 2012 23:10 UTCRoger Curry

Rob I have no further information on the gif. I found it on wikipedia commons photo collection while learning about the dendrite formation. I've seen dendrites actually forming; at 32000 ft above the Gibson Desert, and at fumaroles on Vulcano. Excuse me posting the sal ammoniac image again Rob, I know you've seen it before. The first image is ice crystallising from the influx of my breath, due to the slight leak on the window of the jet. This is normal, and is why the hole is there... exhaling into the window and taking photos may not be considered normal.



9th Sep 2012 02:47 UTCDan Fountain

I'm not sure what the mineral is.
I found these today in a quartz-carbonate vein in the Dead River Shear Zone in Marquette County, Michigan, USA. Associated minerals in the quartz were galena and sphalerite, with minor pyrite and chalcopyrite. The dendrites seem to be "rooted" in what appears to be siderite or ferroan dolomite. Any ideas?

9th Sep 2012 10:50 UTCErik Vercammen Expert

This thread is nearly a "Best of" article: just an introduction, with the headlines of another thread about the compostion of Mn-dendrites, and a warning not to confond dendrites with fossils!

9th Sep 2012 13:09 UTCIan Jones Expert

Let's not forget dendritic gold, this one from Devon:-)

12th Sep 2012 06:56 UTCStephanie Martin

Roger - great entertainment, thank you for those high altitude dendrites and a somewhat shroud-like impression! And those fumarole feathers are sweet and delicate. I wanted to make the gif my avatar, but alas it was slightly too large and I couldn't resize it without losing the animation. I'll work on that.

Dan - Those are really wonderful pieces. It would be hard to know which oxide they are without analysis. Both manganese and iron oxides can form dendrites and both be present. You can't always go by colour because some of the managanese oxides can be brown and likely some of the iron oxides could be black.

Ian, thanks for filling the gap and adding a nice dendritic gold specimen. They sure look much like feathers as the sal ammoniac above. The dendritic form is no accident. It appears in many places, not just trees and plants, but also neurons, rivers and as just mentioned, feathers to name a few.

Here are some cabachons with brownish dendrites in agate from Uttar Pradesh, India. When I have time I will add the sizes and perhaps photoshop the background to black to highlight them better.



12th Sep 2012 07:02 UTCStephanie Martin

More agate cabachons from India,

You can see some brownish "clouds" around some of the dendrite groups.


This is moss agate, while not technically an oxide, it does mimic the dendritic form. These are likely chlorite group inclusions.


12th Sep 2012 19:12 UTCStephanie Martin

Big thanks to Dan for helping to get my avatar on board! And big thanks to Rog for originally posting it!


stephanie :-)

13th Sep 2012 00:20 UTCBradley Plotkin

Here is a dendrite from New Jersey. Snake Hill Quarry, Secaucus New Jersey - Brad.

13th Sep 2012 03:10 UTCRick Dalrymple Expert

I never realized how fascinating dendrites could be. This is one of the best threads ever.

Thanks Stephanie:-D

13th Sep 2012 05:28 UTCStephanie Martin

Thanks Rick, glad you are enjoying it. A thread is only as good as the contributors make it, so thanks so much to you and everyone for your numerous contributions and enthusiasm. :-) That is a pretty high expectation to be one of the best, but we shall try! I was just hoping to share a bit of fun with everyone and learn something in the process.

In addition to the brown tones you often see dendrites that "bleed blue". This is very typical of the medicine bow agate that I have seen. The secondary colour of course depends on which manganese oxide is to blame.

Medicine Bow agate, Wyoming.

Parral Agate, Mexico

Wave or ripple patterns are noted in this agate.


These dendritic talc slabs from Montana remind me much of "Delft Blue" china. Very distinctive.


16th Sep 2012 21:15 UTCWilliam W. Besse Expert

Thought I would share a slab I saw (unknown composition and locality) that is about 20cm by 40cm.

Actually there are several I saw...


And even MORE...


For those of you that go to the Tucson show you might recognize this as a dealer's warehouse on Main just north of Speedway.


19th Sep 2012 22:46 UTCRick Dalrymple Expert

This is a local material. It is often dark red with black dendrites on the outside and then yellow with dendrites on the inside.

22nd Sep 2012 04:01 UTCRick Dalrymple Expert

A couple of more dendrites in agate...

22nd Sep 2012 20:07 UTCStephanie Martin

Bill, thanks for pics from Tucson. I have seen that photo before and until I saw the close up did not realize those tiles were full of dendrites! Gives a whole new meaning to the term "climbing the wall" lol.

Rick, thanks for your latest pics too. The yellow material reminds me of the opalite from Australia.

This week I received a little unexpected bonus. I have a few of these calcites from Ahmednagar, Maharashtra, India, but this one came with a little stow away dendrite inside the longest crystal. None of my other similar calcites from there have any, this particular specimen seems to have a good amount of stubborn matrix attached that appears to be a mix of quartz grains and clay, likely the source for the dendrite. It's not an amazing example but it is very interesting to me coming from this area, I have not seen dendrites on or in any specimens from Maharashtra, an area typically known for zeolites.

Here's the little surprise I found:

whole specimen is approximately 8.x 5.5 cm


I'll be posting more stuff as manage to get the photos done.

23rd Sep 2012 05:18 UTCRick Dalrymple Expert


That is a great find.

Here are a couple of more chalcedony specimens with dendrites.

More to come.

23rd Sep 2012 07:25 UTCAM Mizunaka Expert

Another bonus dendrite hiding on a mimetite specimen from Mexico. The original piece is 7.4 x 4.2 cm. The dendrite section is around 6 mm wide.,0,file=40710,filename=Dendrite.jpg

25th Sep 2012 06:15 UTCStephanie Martin

AM, you always come through with a great contribution! That is a stunning combo. Thanks for sharing that one. I'll be checking my mimetites more thoroughly!

In general I've been noticing a lot more bonus dendrites and it can only add to the appeal of the specimen. For example, this material is not the most photogenic, but it is made more interesting by the additional "artwork".

There are dendrites dotted all over the piece, not uncommon for the material and the clay environs, but despite being small this one caught my eye because it seems to have a shadow or a negative mirror image, perhaps a new dendrite forming.

"Me and my shadow".

Dendrites on palygorskite, also known as mountain leather

Velké Hydčice, West Bohemia, Czech Republic

dendrite approx 4mm

27th Sep 2012 05:20 UTCStephanie Martin

At the Scarborough, Ontario show we came across this strange material: dendritic lead.

The fellow selling them said he "grew" them by dissolving lead in nitric acid and then with the magic of electricity created these forms. So I just had to have them :-D That reminds me, lightning and their by-product fulgurites are also of the dendritic persuasion. I'll have to try and rustle up some good examples of those yet too.

approx 15 mm length

small approx 5mm, larger approx 10mm

27th Sep 2012 09:47 UTCTimothy Greenland

Dear Stephanie,

Thank you for starting this!

Here are some shots of paving slabs around my Brother-in-law's garden in the Drôme department of France. I suspect they are of fairly local origin, but can't guarantee that... The black ones are probably manganese oxides and the co-existing ones probably iron. The jointing between slabs is approx 1 inch wide on the average...


27th Sep 2012 09:49 UTCTimothy Greenland

And just a last one for luck...


27th Sep 2012 11:05 UTCRoger Curry

I'm glad you posted some artificial dendrites Stephanie, here's a couple...

Electrically grown snowflake. (This has been on my hard-drive for donkeys. Could be copyrighted, I'll attempt to find out where I got it and gain permission or removal) (edit - courtesy of Kenneth G. Libbrecht, - well worth a visit! Thanks for the URL Cliff)

Artificial fulgurite production youtube

There appears to be two types of dendrite formation, the ordered crystalline type (ice, ammonium chloride etc.) and the chaotic fractal type (manganese oxides, lead etc). However, this I think is only a scale effect, i.e. if a snowflake continued to grow indefinitely, defects would lead to distortions from perfection, until chaos theory would predict an unorganised large scale form such as is shown by manganese dendrites (2D) or flos ferri & fulgurites (3D). Only a guess...



27th Sep 2012 16:18 UTCDennis Tryon

Another dendritic Agate slab from Mexico

27th Sep 2012 23:12 UTCStephanie Martin

Thanks guys for the posts!

Rog, since you started with a link to the lab created fulgurites, here are some youtube links you might find interesting (if you haven't already seen them) regarding the creation of Lichtenberg figures aka "Captured Lighting" and "Shockfossils". If you needed an idea for a gift paperweight for the exec who has everything, these are rather artful.

The first one is a few minutes long, the second one is about 9 minutes.

After you watch the first one, you can click on the link below it to the shockfossils gallery to see some cool images.


steph :-)

30th Sep 2012 06:25 UTCRick Dalrymple Expert

Here is a fluorapatite with three dimensional dendrites. Click on the image to see the child image showing the base with the wholes of the dendrites. They are about 1-3mm in diameter. I have never seen any other dendrites similar to this.

30th Sep 2012 06:30 UTCRick Dalrymple Expert

Here are some cinnabar dendrites in agate from Nevada. This photo is of a cabochon in a pendant.

1st Oct 2012 04:07 UTCStephanie Martin

Rick, thanks for those. It's always nice to see the cinnabar variety as they are colourful.

As for the 3D dendrites, I actually have something akin to yours, only the samples I have are in calcite. I was reluctant to post them as the precise locality was not confirmed. The locality information supplied was Ougoud, Morocco, but there is no such match. The closest I could find on google was Tishremt N'Ougoud, in Er Rachidia Province. There are similar sounding towns and I always wonder about translation and the often ambiguous info provided to conceal finds, but with the given information this seems to be the best match possible. It is south east of Goulmina. It is rather timely to post this as the conference for Morocco is coming up soon. Perhaps people will be more on the look out for dendrites in their field trips.

There are 2 samples that appear to have been part of the same geode (?) although the pieces don't match together like puzzle pieces. The dendrites wrap around the pieces like a garland. I wonder if there is any connection to all those quartz geodes with goethite needles?

You can see the 3D impressions in the close up 3rd photo.

4.5 x 3.5 x 3.5 cm and 5.5 x 5 x 3 cm



1st Oct 2012 04:10 UTCStephanie Martin

Here is the larger piece:



1st Oct 2012 08:43 UTCDon Windeler 🌟

Stephanie, those Moroccan pieces are way cool, especially the larger one in the second set of photos. Really nice.

I haven't been taking many photos of late, so I'll have to be content with recycling a shot from my gallery. There are lots of dendritic coppers out there, but this is one of my favorite examples from the collection: a 10.6cm long crystallized piece from the Adventure Mine, Ontonagon County, Michigan.

This piece is flat and looks to have grown in a seam, but whatever it dendritically wormed through is now long gone!



3rd Oct 2012 04:27 UTCStephanie Martin

Don, that's a tall beauty!!!

From copper to a copper mineral, this piece exhibits a row of dendrites sprouting up between the layers. There are also hints and spurts of them between other bands throughout the sample. They do look "3D" but I was thinking that it is perhaps just the luck of the way the piece cleaved naturally Normally they are buffed out and polished removing any traces of depth, so I guess you have to catch them before they get smoothed over otherwise you wouldn't know. I didn't need another piece of malachite but couldn't resist the dendrites on the green canvas.

Malachite with dendrites (probably Congo)

overall size 4 x 2.5 cm approx


5th Oct 2012 06:11 UTCRick Dalrymple Expert

Another dendritic copper from the Bingham Copper Mine...

5th Oct 2012 06:17 UTCRick Dalrymple Expert

Another one from Bingham, turquoise with dendrites on it. I don't think they are in the turquoise, just on it.

5th Oct 2012 06:29 UTCRick Dalrymple Expert

And a silver from Germany...

5th Oct 2012 06:41 UTCRick Dalrymple Expert

I know coppers have been done here but I really like this one from Namibia,,,

6th Oct 2012 00:53 UTCRick Dalrymple Expert

Stefanie, I like those 3D dendrites. I see similar ones in a similar rock here every once-in-a-while:-)

This stuff is listed on mindat as jasper from china but it is not a jasper. The slab is so soft that it actually has warped from sitting on a stand. It is now slightly bowed in the center. I would say it is a very soft siltstone or claystone.

I do like the tree-like dendrites.

12th Oct 2012 06:56 UTCStephanie Martin

As I was mentioning above regarding buffing the dendrites for lapidary items, this can be seen in the egg below. The longer dendrites show areas that were not completely buffed out. Sorry about the white spot light refflections...

From Peru

Dendrites, calcite


Some cabachons also from Peru, material is known as Machu Picchu Stone and contains calcite, quartz and the darker red areas are indicated as being caused by the presence of cuprite.


12th Oct 2012 07:03 UTCStephanie Martin

More from Peru, these are dendritic pink opal carvings

A matched pair of bluish dendritic "landscape" opals


12th Oct 2012 07:05 UTCStephanie Martin

another carving, this one is Tanzanian opal


13th Oct 2012 16:29 UTCdaniele ramoino

hi everyone,

Thanks to Stephanie and Roger, i just found to have a rock with dendrites,

it come from Maroc desert


13th Oct 2012 18:01 UTCJames Pool

Here's a closeup of what is likely dendritic silver in an unpolished slab of sowbelly agate from Creede, Colorado. Much of the silver ore from there occurs in banded amethyst seams that an early miner called sowbelly agate due to the bacon like appearance of some slabs although in a different color. The specific mine for this slab is unknown but it may be from the Commodore.

There is a very 3d appearance for the dendrites when the slab is wet in water. The largest dendrite is about 1/4 inch or so.

26th Oct 2012 04:51 UTCRick Dalrymple Expert

I thought I would revive this thread. I am sure there are many more dendrites out there.

This is a front and back of the same slab. I just can't decide which is the front and which is the back:-)

It is from a Priday Thunderegg I collected about 12 years ago.

28th Oct 2012 05:51 UTCStephanie Martin

Thanks Rick... I have much more to post, just getting things photographed is a challenge...

Roger mentioned flos ferri on the previous page, and I have always found these funderful. Here are a couple, and Gail has posted a lovely blue one on the favourites thread if you care to have a peek at that (page 27). I have a little green one but it doesn't have many branches to show the form well.

Aragonite var flos ferri (unforunately some branches were damaged in transport)

Příbram, Central Bohemia Region, Bohemia (Böhmen; Boehmen), Czech Republic

approx 30 x 20 x 20 mm

Aragonite var flos ferri

Bisbee, Arizona, USA

approx 6 x 6 x 5 cm


In addition, cracks and crack formation also fall into dendrite territory. Below is a septarian concretion from Morocco that shows such crack formation that has been filled in by calcite. This is much different than the lovely dendritic concretion section shown by Daniele on the previous page also from Morocco. I hope Daniele finds more of that material to post, it is quite amazing.

Calcite, sedimentary/septarian nodule

Oujda, Morocco

9.5 x 7 cm


30th Oct 2012 15:21 UTCDan Fountain

I was out digging for pyrolusite a while back and this was the first piece of rock I split out. My previous "best" dendrites flank it.

31st Oct 2012 04:19 UTCMatt Ciranni

Does this count? Picked this up in the Marsing/Homedale area (near the Idaho/Oregon border) last summer. It's some type of dendritic agate that is commonly found in that area. Some local jewelers apparently gather and cut slabs of this material, and create pendants out of it.

31st Oct 2012 06:02 UTCStephanie Martin

Dan, I just have one word: W.O.W! (picks jaw off floor)...


31st Oct 2012 06:04 UTCStephanie Martin

Hi Matt,

Thanks for posting. Yes, there is at least one dendrite that I can confirm about half way down on the far right of the specimen, the other dark spots are hard to tell if they are just dirt or a coating of some type, but there could be more dendrites hiding in there.. Mostly these look like quartz stalactites which also do follow dendritic form. Oregon does have some lovely material to contribute!


stephanie :-)

31st Oct 2012 13:25 UTCRick Dalrymple Expert

I knew there were more great dendrites out there(tu)

Stephanie, I don't get how a septarian is a form of a dendrite?

I do love the flos ferri though:-)

31st Oct 2012 13:33 UTCRick Dalrymple Expert

Here is a blue aragonite from a mine only 20 minutes from my home...The Tintic Standard Mine, Eureka, Utah

and one from a mine right around the corner from the...The Baltimore Tunnel, Mercur, Utah

31st Oct 2012 17:03 UTCStephanie Martin

Those are beautiful Rick!

Regarding the septarian, it is not the actual concretion, but rather the crack formations from the weathering process and those have been filled by calcite in the nodule. Cracks are not actually dendrites themselves, however their formations are subject to the same fractal chaos and therefore can be lumped generally under the dendrite umbrella. Hope that helps.


stephanie :-)

31st Oct 2012 18:48 UTCRick Dalrymple Expert

Thanks Stephanie,

I think we have a difference in semantics. The internal structure is not a weathering process. It is caused by the internal collapse of the hollow cavity. The hollow cavity is thought to be created when a biological mass, like algae, decay away. Many of the solid ones have other nucleus such as ammonites or other shells. I even have one that I am sure is an algal ball that resembles dinosaur bone. There is a lot of research done on these from Utah. The ones from Morocco have the same genesis. BTW: I have collected the ones here in Utah many times. It is a great field trip and if you are ever in the area, I would be glad to show you around.

As for the fractal pattern (not really chaos as fractals are not random), I couldn't agree more. They are wonderful and that thought adds a whole new dimension to this thread. I am now looking forward to adding a whole new batch of images:-)

3rd Nov 2012 06:00 UTCRick Dalrymple Expert

Here are a couple of polished agate cabs. My son Zeke did the cutting and polishing.

3rd Nov 2012 06:01 UTCRick Dalrymple Expert


3rd Nov 2012 10:19 UTCRock Currier Expert

Rick, that a really beautiful dendrite and cab. I see you have uploaded it to our gallery. Thank you for that. Do you know which Oregon locality it is from?

3rd Nov 2012 12:34 UTCPhilip Bluemner Expert


I love dendrites since being a little one. It's so fascinating and fun following the branching growth.

Here's a dendritic fluorite from Moepe Mine, South Africa

Best regards


3rd Nov 2012 15:58 UTCGlenn Rhein

Wow Rick, that blue Aragonite is cool stuff

About 2-3/4 inches , Most of the Meionite here in Amity has this dendrite coating but this is one of the darker pieces.

3rd Nov 2012 22:41 UTCRick Dalrymple Expert

Rock, Thanks. I got the slab in a collection and it was labeled with pencil " dentrite--Oregon", unfortunately:-( I really wish there had been more.

Glen, Thanks. I love that piece too. My friend collected that about 20 years ago when there was lots in the mine. Now it has been reclaimed:-(

4th Nov 2012 02:07 UTCRick Dalrymple Expert


Here is the septarian I mentioned earlier, with the algal ball in the center. It is from Muddy Creek and was collected last year by a friend.

4th Nov 2012 02:21 UTCRick Dalrymple Expert

Chrysoprase with dendrites.

4th Nov 2012 02:28 UTCRick Dalrymple Expert

This material is often sold as jasper but it is really a siltstone. The dendrites are considered stromatolite, though I don't know that they have been studied.

4th Nov 2012 03:11 UTCGlenn Rhein

Rick Dalrymple Wrote:


> Glen, Thanks. I love that piece too. My friend

> collected that about 20 years ago when there was

> lots in the mine. Now it has been reclaimed:-(

Hey Rick, No mine here in Amity NY just the backyard and some woods. What mine are you refering to ?

4th Nov 2012 03:54 UTCRick Dalrymple Expert


It is from the Tintic Standard Mine (Tintic Standard Mines 2 & 3), East Tintic District, East Tintic Mts, Utah Co., Utah, USA.

It is about 30 minutes from my house. Unfortunately, it has been reclamated recently.

5th Nov 2012 05:43 UTCStephanie Martin

Rick, thanks for the notes regarding the Utah septarians. I have no argument regarding the formation of the concretion around a nucleus or the subsequent internal collapse. My wording was perhaps over simplistic in an attempt not to get into too long a discourse. From my understanding of their formation these concretions were subject to different geologic processes, including weathering when the seas dried, during their longterm formation (or lack thereof of weathering in an arid climate after the seas dried from their original birth in water). Then followed by subsequent rehydration and solution resulting in calcite filling. And regarding fractal and chaos, again this was over simplistic, as I was referring to stochastic processes in 3 dimensions. So as you said, it is semantics :-)

I have a bit of catching up to do so I better get cracking (pun intended)...:-D


5th Nov 2012 06:07 UTCStephanie Martin

Thanks to all for continued interest and posting awesome specimens!

Rick, that cab IS your own little world... it's cabtastic. Kudos to your son for doing such an outstanding job orienting the stone to full potential.

James - thanks for posting that silver, I will definitely have to look at my sowbelly agate a little closer!

Philip, that is really cool fluorite from an unusual location. That's what I like to see :-D

Glenn, you know I love those! Were you ever able to determine if the dendrites were alanite? In any case that's another lovely specimen.

Getting back to dendrites...

from Kazakhstan

dendritic opal rough

4.5 x 4 x 3 cm approx

agate cabachons

42 x 21 mm and 45 x 17 mm approx

5th Nov 2012 08:58 UTCAntónio Joaquim Monteiro

Dendrites from Serra da Mina mine, Cercal.


7th Nov 2012 00:21 UTCAlex Homenuke 🌟 Expert

I've been meaning to photograph this and post it since this thread began. I don't know how you all find the time to do this :)-D

Descloizite dendrites in dolomite(?) surrouded by botryoidal smithsonite, 10cm, Berg Aukas

9th Nov 2012 07:54 UTCStephanie Martin

Antonio and Alex, very intriguing samples!

Antonio - the white dendrites are very unusual and very contrastive, I am curious what mineral they are.

Alex - I don't think I have ever seen descloizite dendrites! Amazing specimen. Glad you found the time to share that treasure.

Here's one from my weird file - a drilled agate pendant, but it has an odd formation of a completely encased bubble inside the agate that has a globular type dendrite forming in it. Unfortunately the agate is too thick and a bit milky so it doesn't allow for a clear focus on the blob, so it will always remain fuzzy, but there is no mistaking it's silhouette. "The Mushroom". The supplier tried to get more information for me on the origin of the material, however the only available information was that the agate location was from China. I am not convinced, but that's all that I could find out. I suspsect it could really be from Indonesia or possibly India. Approx 32 x 22 mm overall.


9th Nov 2012 11:58 UTCRui Nunes 🌟 Expert

Dear Stephanie,

Regarding Antonio's dendrites: I have something similar from this mine but not so pretty. I think it's "sugared" barite in a mn oxides environment.

Best wishes


9th Nov 2012 20:47 UTCDan Costian

I've never seen red dendrites (hematite I guess) within a crystal of yellow apatite (Cerro del Mercado Mine, Mexico).

9th Nov 2012 23:32 UTCDan Costian

These dendrites on quartz are from Wyoming. They are crystals, with metallic luster, looking like sulfides.

Can anybody tell me what can they be? They look like manganese oxide but probably are not.

17th Nov 2012 04:12 UTCRick Dalrymple Expert


I don't know what those dendrites are but they are cool(tu) Why don't you think they are manganese oxides?

Here are some more I came across...

The first one is white dendrite-like feathering in an Oco agate geode. These are common but still beautiful.

17th Nov 2012 04:16 UTCRick Dalrymple Expert

This two are manganese oxides in what is commonly called Tiffany Stone.. It is the beryllium ore "bertrandite" colored with fluorite and manganese oxides. It is mined near Topaz Mountain, Juab County, Utah

17th Nov 2012 04:31 UTCRick Dalrymple Expert

This is one of my favorite. It resembles a fire work or maybe a dandylion, or maybe a signal flare...

17th Nov 2012 04:42 UTCRick Dalrymple Expert

This is an unusual one. It is dendrites of hessite in quartz. There is some minor gold mixed in. It looks more dendritic in person.

17th Nov 2012 05:03 UTCRick Dalrymple Expert

Here are some beads with dendrites.

One is green chrysoprase with dendrites from Australia and the other is dendritic opal but I don't know where it is from.

19th Nov 2012 04:26 UTCRick Dalrymple Expert

Here is a dendrite in malachite. I don't know if it is a manganese oxide or something else.

19th Nov 2012 04:27 UTCRick Dalrymple Expert

Oh yea, the field of view is about 4cm.

19th Nov 2012 04:39 UTCRick Dalrymple Expert

Here is a polka dot agate slab from Oregon

19th Nov 2012 06:02 UTCStephanie Martin

Dan, those are remarkable and intriguing specimens! The apatite is really drool worthy and I am also curious to know what those metallic dendrites might be in your other piece. There has always been speculation that metallic dendrites are pyrolusite, however that has not yet been reported with analysis. I will try to see if I can find any references from that area that might indicate any probable ID.

Rick, thanks so much for your dedication. Great pieces, I really love the "dandelion" or however you choose to name it. The Hessite was a nice touch also.

I am still having a bit of fun with agates, these come from the same lot as the "Mushroom" above. There seems to be a number of them that suggest images, at least in my overactive imagination.

rose and thorns

celestial body rising on horizon

crooked ghostly smile

19th Nov 2012 16:32 UTCAlex Homenuke 🌟 Expert

Or is it a moustache for "Movember"??

19th Nov 2012 19:25 UTCJohn A. Jaszczak 🌟 Expert


Interesting that the dendrites seem mostly to have simple chemistries. Here is a lovely stellate dendrite of graphite on graphite from the Gouverneur Talc Company mine #4, Harrisville, Lewis Co., New York.

23rd Nov 2012 22:24 UTCDean Allum Expert

I ran across this link regarding the chemistry of dendrites. Perhaps it is appropriate for this thread:
Caltech:manganese dendrites

cheers -Dean Allum

23rd Nov 2012 23:33 UTCDan Costian

Interesting article. However, the hollandite inclusions appear as stars (crystal spray) not as dendrites.

25th Nov 2012 05:52 UTCStephanie Martin

John, that is a spectacular graphite! And very appropriate since we just received our first signifcant snowfall of the season. Very pleased that you shared that one. Thanks for an unusual dendrite!

Dean, thanks for posting the link. Yes was aware of it but didn't think to post it, great that you did.

Dan, I too always wondered about those hollandite stars in quartz, if they qualify as dendrites? There are lots of dendrites that do appear star-like, but these particularly seem to be more acicular than stellate. Will have to look into that more.

Today I am sharing some samples of dendritic uraninite and schoepite from the Ruggles Pegmatite, Grafton, New Hampshire

approx 3 cm

end cut, one side polished

rough unpolished

25th Nov 2012 05:59 UTCStephanie Martin

More dendritic uraninite, along with the alteration schoepite group minerals including soddyite and fourmarierite.

ex Ben Shaub circa 1930.

Ruggles Pegmatite, Grafton Co, New Hampshire

approx 3.5cm both sides polished


alternate view

25th Nov 2012 13:06 UTCReiner Mielke Expert

Can't get over the polished radioactives, talk about radioactive waste produced, gives me the shivers. Beautiful looking stuff that Ruggles mine dentritic uraninite though.

25th Nov 2012 17:32 UTCStephanie Martin

Thanks Reiner. Yes an interesting thought about the by-products. There were recently some large cabinet pieces of the cut material that became available and those were snapped up instantly, so there are some really nice museum quality cabinet pieces out there. The second piece above is pretty hot, we couldn't get a reading on my brother's cold war Russian geiger counter as the reading was over the capacity that it could count. I can't remember what the first one registered but it was less than the second piece.


stephanie :-)

25th Nov 2012 17:47 UTCMartin Rich Expert

Hi all!

Nice threat. In the pic below you can see dendrites of Graphite in Granulite. Orning near Melk, Lower Austria, Austria. 9 x 13 cm. Coll. & Photo Martin Rich.

29th Nov 2012 00:11 UTCMartin Rich Expert


The sample I show above has a wrong ID! This an old specimen (1900) from the collection of the Abbey of Melk, Lower Austria I swapt some weeks ago. It was labled as Graphite. After studying a lot of old literature, I´m sure this dendrites are Markasite/Pyrite. The austrian mineralogist MEIXNER analysed this in the 1950´s.

Sorry for the wrong ID.

29th Nov 2012 02:01 UTCDan Costian


Two reasons pro manganese oxides: 1) shape; 2) the bluish diffuse color around which sometimes accompany manganese oxides dendrites.

One reason against: the metallic luster which might indicate some sulfides.

Now, what you show as Tiffany stone does not resemble as such. Google and ebay are full of pictures of that complex mineral which indeed consisted of fluorite (purple in this case), fluorapatite, bertrandite (berylium compound) yellowish and sometimes afghanite.

29th Nov 2012 03:22 UTCRick Dalrymple Expert


I agree they are probably manganese oxides based on color alone.

Tiffany Stone is not a mineral. It is a gem-term for the beryllium ore at (what is not) Wellman Resources. It is composed of bertrandite clay that is impregnated by ground water laden with fluorite, manganese, quartz (agate), and sometimes hylite opal. These have all been confirmed. I have never heard of afghanite being confirmed there but I have only seen one paper on it. The dendrites were confirmed as manganese oxides. The orange and peach colors are also caused by manganese.

There is also small traces of uranium salts that make the agate fluorescent. There is enough of the uranium that when the company was Brush-Wellman, they contaminated the ground water with the waste pile.

I have some more pieces I will try to get photographed tomorrow and post.


Those uraninite et. al. dendrites are really cool. I have several specimen of that and now I want to polish them. But they are radioactive and the dust... but I want to polish them but they are radioactive... but I really want to polish them:-D What to do:-S

3rd Dec 2012 03:17 UTCStephanie Martin

Hi Martin, that is a nice sample of dendrites and thanks for the correction. My first thought was actually a silver or arsenide mineral but if this has been analysed then there is no guessing.

Rick, your indecision reminds me of Peter Griffin, just before he puts his finger in an electric pencil sharpener. Moral is, don't do it!

This specimen may look like aragonite but it is actually dendritic phillipsite.

Dendritic Phillipsite with some natrolite needles present in vugs

Höwenegg Quarry (Hewenegg Quarry), Immendingen, Hegau, Baden-Württemberg, Germany

79 X 33 X 30mm


3rd Dec 2012 03:25 UTCStephanie Martin

This specimen is covered in dendrites but adding a bit of colour and interest to the mix is the additional aurichalcite. Both this specimen and one above from Robert Vaňo.

Dendrites on Quartz with Aurichalcite

Stříbrník, Nýznerov, Žulová, Jeseník, Moravia, Czech Republic

60 X 50 X 32mm



3rd Dec 2012 16:06 UTCD Mike Reinke


Have you ever heard of phytoremediation for radioactivity? Sunflower plants clean up radiation. Google it, it's amazing what plants can take out of soil, all kinds of toxins. So plant a area of sunflowers, and do your polishing out in the middle of 'em, just don't breath...

Stephanie, great thread. Never realized they were so cool, and diverse. My first thought was more like ' been there, seen them...' thanks!

3rd Dec 2012 21:13 UTCRick Dalrymple Expert


Thanks for that tip. Maybe they can use the technology to clean up some of the radioactive accidents around the world. Oh, and maybe nuclear power plants should plant them around the reactors in case of a leak;-)

I'll have to read more about this.

All joking aside, this does sound like it has potential. I wonder if it absorbs radon. Along the Wasatch Front, here in Salt Lake City, we have a huge pluton that produces some high levels of radon in peoples basements.


Another great set of pictures. I hope to get some photography done tomorrow and upload more this week. I found my turquoise with dendrites finally.

3rd Dec 2012 21:48 UTCDan Costian

You are absolutely right Rick, Tiffany stone is a complex rock. I attached pictures from my collection.

4th Dec 2012 00:18 UTCStephanie Martin

Pavel, thanks for the photos. Did you confirm the pyrolusite by analysis? I have not found confirmations of true pyrolusite dendrites, most that were thought to be pyroslusite turned out to be managanese oxides. Any info would be great.

Best Regards,


4th Dec 2012 02:30 UTCPavel Kartashov Manager

Yes, it was confirmed as some polymorph of MnO2, but nsutite or ramsdellite are much more rare then pyrolusite.

Microprobing show absence of cations other than Mn in the mineral. And wet chemical tests prove absence of Mn2+ in it.

Of course, initially these dendrites were formed as manganite or some other Mn hydroxide. But conditions in which the specimen was collected were extremely favourable for dehydratation processes - temperature of black rocks up to 60-70 Co on the sun, air moisture on 5 % level and low atmosphere pressure - heighth ~2000 m over a sea level. In other words, this pyrolusite is secondary.

Look also on not exactly dendritic but all the same very fanciful manganese mineral:

4th Dec 2012 02:49 UTCStephanie Martin

That is fascinating Pavel. Thank you for the explanation, this is helpful.

Interesting specimens and I am sure that we will learn more about the unnamed samples in future.

Best Regards,

stephanie :-)

8th Dec 2012 12:48 UTCMatt Wall

Hi Stephanie and Everyone,

I got this nice Kasolite from Shinkolobwe from Leon Hupperichs today, and looking at the back it appears to have some nice dendritic Uraninite. I don't know if Uraninite can occur like this, I assume it does, but I'm not certain. See what you think, (pic attached). :-)

Kind regards,

Matt. :-)

8th Dec 2012 20:50 UTCJohn A. Jaszczak 🌟 Expert

Nomarski DIC images of stellate dendrite graphite overgrowths on a unique graphite crystal (#3270r) from the clintonite type locality, Amity, Orange Co., New York. (a) Overall view of the crystal (~1 mm field of view; 10× objective lens) showing approximately four generations of growth steps. The steps are relatively smooth and straight parallel to the <100> directions, but show stellate dendritic growths along the <110> step directions.

The second image show close-up images of the stellate dendritic sections taken with a 50× objective lens. (Images taken with an Olmpus PME-3 microscope, Nomarski DIC prism and polarizers, and a Leica EC3 digital camera.)
~0.1-mm field of view

For more information an images see "Stellate surface features on graphite from Crestmore, California and Amity, New York." Mineral News vol. 28 #11 (2012).

22nd Dec 2012 05:37 UTCRick Dalrymple Expert

I finally found my turquoise cab with dendrites.

22nd Dec 2012 13:14 UTCRock Currier Expert

It looks like a manufactured material. However determining exactly what has been done to it if anything would likely cost much more than the stone was worth. Sort of like determining what sort of coloring treatment has been given to an agate. I can undoubtedly be done, but would you be willing to pay $100 to $200 to find out? If we get real lucky, the guy who did this particular kind of treatment will read this and tell us just exactly what was done to produce your kind of stone. But then, it may have been done in China by a guy who doesn't speak English and he probably works for a company that makes a living doing this kind of work. Who would want to break their rice bowl to tell you about your stone?

30th Dec 2012 04:13 UTCRick Dalrymple Expert

I don't understand Rock. What looks like manufactured material?

30th Dec 2012 05:07 UTCRock Currier Expert


It looks like no natural turquoise I have ever seen. That's why I suggested that it might not be natural. I may not be correct. We may get lucky and someone may come along here and say, "Yes, I dig that stuff out of my mine all the time and this is the locality." I hope I am wrong.

30th Dec 2012 17:11 UTCRick Dalrymple Expert


Hey, I dug that myself. Really, I collected it at the Color Back Mine in Nevada in 2010. I polished it too. I have uploaded a bunch of specimens from the mine from when I was working with the mine owners and collecting there. Although, looking at the photo I can see why you thought it might not be natural.

If I had to take a guess it is a solid solution of turquoise and variscite, hence the odd color. There must be some silica in the mix as well. It is harder than most turquoise I have cut. This stuff comes in thin seams and when you tap on pieces they sound like glass.

The mine owners call it "blue ice" and they have been trying to market it for a couple of years now but they don't have much. They are asking $800 per pound for it (that is rough cleaned from matrix). I know they have sold several 1 to 5 pound parcels so it should start showing up in jewelry soon. I have about 2 five gallon buckets of rough from the mine and as I polish it I hope to find more dendrites in it.

31st Dec 2012 08:15 UTCRock Currier Expert

It might be interesting to pay for an x-ray of the stuff so you can find out exactly what the stuff is. If you are selling it for several hundred dollars a pound your customers probably deserve to know what it is they are buying.

31st Dec 2012 15:42 UTCRick Dalrymple Expert


I am not selling it. The mine owners are TRYING to sell it for those prices. They haven't sold much in two years.

I was just saying that I collected some and have polished that piece. I only posted it because of the dendrites.

Mike, one of the mine owners, said it was all studied and identified by the "guys" at the school in Reno. I haven't seen any published papers on it.

1st Jan 2013 09:14 UTCRock Currier Expert


Ask them if the school they are talking about is the school of mines and who were the guys.

1st Jan 2013 16:16 UTCRick Dalrymple Expert


I believe it was somene from the school of mines, but I am not sure. I wont see them again for a few months but when I do I will ask.

1st Jan 2013 21:52 UTCRock Currier Expert

Sometimes these things are a mixture of minerals and not clear cut like turquoise, or chrysocolla and it is hard to give them accurate names. The market place demands clear names. So when something attractive in the way of a rock is found, it is given a new name that refers to that thing, like primavara stone, spinach stone, new jade etc. Even though the stuff may not be pure turquoise it is much better to call it turquoise for commercial purposes because of the preexisting name recognition. Even if it is clear cut like zoesite, the trade calls it Tanzenite because it has more sizzle and helps it sell better and it is now unstuck from the name of a common not very valuable mineral. So whats in a name? Well it turns out there is a lot in a name.

1st Jan 2013 23:00 UTCRick Dalrymple Expert


I completely agree. A name is everything. THat is why they just call it "ice blue" turquoise.

2nd Jan 2013 02:35 UTCStephanie Martin

John, awesome photos! Really interesting stuff. Thanks for posting those here.

Rick, that blue ice is surely cool! I am curious to know if it is a mix with variscite as may be suggested and if you can find out for sure.

My current laptop is running on full, so photos have been on hold until I get my new desktop set up shortly. But I have to start the New Year off right so here is a dendrite plate with a wish to all for a happy 2013.

It is rather long and difficult to photgraph well, and it my largest dendrite specimen to date.

Manganese Dendrites

Kagawong, Billings Township,

Manitoulin Island, Ontario, Canada

31 x 9 x 3.5 cm


2nd Jan 2013 15:31 UTCAlex Homenuke 🌟 Expert

Turn it about 160 degrees counterclockwise and it has the same general shape as Manitoulin without the inlets

3rd Jan 2013 02:36 UTCStephanie Martin

I must admit I was tempted to photograph it that way but thought it was my overactive imagination again. I guess I'm not the only one who has that problem ;-)


stephanie :-)

3rd Jan 2013 08:35 UTCRock Currier Expert

This may be the greatest accumulation of images of dendrites ever made. Its a shame that most of them are here only as attachments and not uploaded to our image bank.

3rd Jan 2013 18:06 UTCBill Cordua 🌟 Manager

Here are dendritic iron? manganese? oxides in a flake of muscovite. Don't know the locality. field of view is about 2 cm. Took this with my Dino-Lite, backlit.

3rd Jan 2013 20:26 UTCDon Windeler 🌟


Your reminder about including these in the image bank is always a good one; unless it's something off topic or goofy I usually try to post in my gallery first.

I'm curious as to recommendations for the best approach in this particular thread, though. Setting aside the clear-cut examples where the minerals are known, there are a lot of cases of "dendritic Mn-oxide schmutz" where someone probably took a pic more for aesthetics than as a mineral. How best to tag these, especially when this stuff can show up anywhere and usually isn't included in the locality listings?

I may have partly answered myself, though; as I poke around, I see "Manganese oxides" is a catch-all bucket option one could use.

Will try to contribute some of my own soon -- I picked up a few interesting things on the Morocco trip that haven't made it in front of a camera yet.



4th Jan 2013 03:22 UTCGeoff Van Horn Expert

Romanechite dendrites on microcline from the Wausau Pluton in Marathon Co, Wisconsin. I accidentally collected this in June of 2012. I was digging smokey quartz and Wausau moonstone (anorthoclase) and this was attached to a very nice smokey cluster. I knocked this part off with my hammer before noticing the dendrites.

5th Jan 2013 09:54 UTCRock Currier Expert

I have created a thread in Best Minerals and a stub of an article for Dendrites. Would someone here like to work on it and complete the first draft of the article on dendrites?

5th Jan 2013 15:51 UTCStephanie Martin

Rock I have been going through the galleries and selecting some fine examples which I will link into this thread eventually.

I planned to do an article on dendrites but maybe I will just work on it as a Best Minerals project instead as likely can incorporate much of the information into that format. Thanks for thinking of doing it as a Best Minerals topic.


stephanie :-)

5th Jan 2013 20:41 UTCRock Currier Expert

Stephanie, I would encourage you to work on the best minerals article. There is a lot of good information there that should be buried in old thread postings. Just go to the Dendrite stub under D best minerals and in the message field like you find at the bottom of all of these thread pages, just start working. Just start to do something there, and Ill set up the basic format in your message to help you along and then you can add, cut or edit what ever you want. If you stick through the process till the end and do another best minerals article, Ill make you a moderator. By the time you finish a rough first draft on dendrites, you will know if doing best minerals articles is something you enjoy doing. Ill be around help and advice if you need it.

6th Jan 2013 00:06 UTCRoger Curry

Stephanie, I would love you to do this.



6th Jan 2013 03:07 UTCDon Windeler 🌟

I love the "Best of..." series, so it'd be great to see this thread form a kick-off. (And thanks for your enthusiasm, Stephanie!)

So here’s my contribution for the day to the thread, both pictorial and informational. Back in 2008 I was thrilled to purchase this piece, labeled as native copper inclusions in gem chrysocolla from Arizona. (4.8 x 3.0 x 0.6cm, imaged with a cutout of white paper behind it using a Canon photocopier. Will upload to my gallery and include a link here when approved – sorry it’s not a better shot.)

copper dendrites in agate

Not quite, it turns out. Si and Ann Frazier saw the piece at a club meeting and told me the dendrites were artificially added. Apparently there was a gent in Phoenix named Paul Rabbit who’d developed a process to induce copper or tin dendrites in agate, by soaking an agate in a Cu or Sn solution, then putting it in contact with a piece of iron to force precipitation. (I’m oversimplifying, as it apparently took the guy over six years to work out the right way to do it.) He called them “Fischer stones” after Dr. George W. Fischer, who’d self-published a book in 1991 called “Gemstones and chemicals: how to create color and inclusions.”

The source material was “snakeskin” agate from eastern Oregon. According to the Fraziers, this agate is microgranular and has randomly-oriented fibres, which makes it more amenable to the dyeing and dendrite-production process. Since then I’ve bought a Malheur County, OR, nodule of the same from Dana Slaughter, pictured below. (6.5 x 5 x 6.5 cm, also soon to be posted in my gallery.) This picture was taken by Dana and is used with his permission. While not obvious in my picture above, the edges of the polished slice look a lot like the rind on this snakeskin nodule.


Snakeskin agate, Malheur Co., Oregon

The above info on copper dendrites in agate is summarized from a few paragraphs in a Lapidary Journal article the Fraziers had written, cited below. I don’t actually have the article, just the paragraphs Ann sent me, but it sounds like required reading for this thread!

Frazier, Si and Ann (2002). Dendrites: Nature’s Line Drawings. Lapidary Journal 32, 2-02. (sorry, I’m going off an internet search and am not sure on the volume / page numbering...)



6th Jan 2013 10:51 UTCRock Currier Expert

Don, the only images we use in Best Minerals are those that are uploaded formally to the Mindat gallery. The uploading process required that the uploaded specify the copyright type that will apply to the image. Without the copyright specification we are reluctant to use them in best minerals. That's why I continually request people to upload their images rather than just attach them to thread posts.

6th Jan 2013 18:34 UTCDon Windeler 🌟

Sorry if I was sloppy in my verbiage, Rock. I wasn't actually proposing the pic above as a "Best of Dendrites" when referring to my contribution, more just was adding to this ongoing thread. I figured the Fraziers' LJ article might be of interest.

I am going to post the pics later today and will link them in when approved -- I just had the inspiration to write down some things after remembering this piece and didn't want to wait around until they were approved to post my comments.

But I sympathize with your frustration at great pics that never make it into the galleries!



7th Jan 2013 03:18 UTCJohn Truax

This malachite egg belongs to a friend.

Interesting thread .... thanks all.

7th Jan 2013 04:55 UTCStephanie Martin

John T. that is a lovely feathery malachite egg! And yes those fibrous malachite specimens qualify as dendrites as can clearly be seen in the egg. I have never seen one polished like that before, rather unique I should think. Eggxellint! :-D

Geoff - that was a happy accident I'm sure (previous page). Nice that you decided to keep the dendrite and share it here. Enjoy it.

Don- great info! And intrigued about those artificially induced dendrites! Your piece reminds me of the copper mineral? dendrites in Dominican Republic pectolite/larimar. I am looking forward to seeing your dendrites from Morocco. One of our club members was at the conference and showed us their trip, and one spot specifically where dendrites littered the ground!

Thanks to all for continuing to contribute to this topic!


stephanie :-)

8th Jan 2013 05:17 UTCDon Windeler 🌟

Gallery entries now linked in above message.



12th Apr 2013 21:37 UTCRick Dalrymple Expert

This is lepidolite and I think the dendrites are feldspar but they could be beryl.

Unfortunately, I didn't get to keep this specimen. I only got the hold it for a minutes.

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