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Best examples of trapiche emerald crystals?
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Jim




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PostPosted: Feb 26, 2010 13:19    Post subject: Best examples of trapiche emerald crystals?  

I was curious if anyone had photos of collector quality trapiche emerald crystals. I've seen some photos of crudely developed or non-gemmy trapiches, but I'm conducting research on natural, gemmy examples.

Aside from what's found on Mindat and in the Barlow book, can anyone share photos of great examples?

Thanks!

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Jason




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PostPosted: Feb 26, 2010 14:30    Post subject: Re: best examples of trapiche emerald crystals?  

I have seen a couple photos here and there..don't recall any that were gemmy or really nice..will have to look around..is the research just on trap. emeralds or other traps. like sapphires
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PostPosted: Feb 26, 2010 15:25    Post subject: Re: best examples of trapiche emerald crystals?  

I would also love to see emerald trapiche crystals in their natural state. Firsthand, I've only seen trapiche emeralds cut as cabochons; I've never seen the original unharmed crystals. There is a Van Pelt picture in the extraLapis Emerald issue of a group of cabbed trapiche emeralds alongside a crystal, but it is hard to see if the crystal is altered or much else about it. There are beautiful pictures of different types of trapiches in John Koivula's PhotoAtlas Vol. 3, including one which has a double core resulting from interlocked columnar growth. There is also an interesting one pictured in which the "spokes" themselves are emerald (instead of the black mixture of minerals) and the surrounding material is white - in that case, I wonder would a mineral collector leave the matrix? It would be interesting either way.

An aside regarding another trapiche in the beryl family, John (K) showed me an aquamarine specimen which was a cluster of long, very slender crystals, each ending in a flat termination revealing a trapiche structure! There is a picture in the Gems & Gemology Fall 2008 issue, page 276 of the same or similar cluster, along with a photomicrograph of the termination which shows the structure. In that report he wrote that these originated from the Erongo Mountains of Namibia. Starting from the center, the included "spokes" seem to fan out to the prism faces and the gemmy areas span the junctions of the faces in between the spokes (a picture would tell a thousand words here...). In the Van Pelt picture of the emeralds, it seems like the crystal has been pre-formed for cutting as its cross-section looks round ( ? hard to tell from the picture), and so it is hard to know if it is formed in the same way as the aquamarine. In both of John Sinkankas' books on Beryl, there are good overviews of the formation, but without color images of a natural crystal.

There are also corundum trapiches which I have seen in Thailand cut into cabochons; I believe from Burma. I haven't seen any of these as spectacular as the emerald and aquamarine trapiches mentioned above.

Best wishes,
Elise

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Jim




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PostPosted: Feb 26, 2010 16:04    Post subject: Re: best examples of trapiche emerald crystals?  

Amethystguy and Elise,

Thanks for the information. I find all trapiche effects fascinating but my research is focusing on trapiche emeralds in their natural state at this time.

Funny you mentioned the "double core" trapiche emerald. That cabochon -- which seems unique to this point -- used to be in my collection. That stone and a large trapiche emerald showing chatoyancy were two of my favorites. Those gems were sold to a major collector for his research collection, so they're in good hands.

I'll definitely check out the other photos you mentioned Elise -- some of these I may not have seen yet.

Gracias!

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Elise




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PostPosted: Feb 26, 2010 17:25    Post subject: Re: best examples of trapiche emerald crystals?  

The only other picture I find of a crystal in its natural state is again another Van Pelt showing a crystal looking down the c axis (G&G W 87, 240). It makes one wish for the Google Maps toolbar button that lets you rotate to street-level to take a look at all sides!

I looked through every book on beryl/emeralds and mineral portraits I have, including Ron Ringsrud's latest and some I'd put on a shelf of "I don't read this language yet." I just don't find any pictures of the unaltered crystals - they must chop them up immediately.

I happened to have everything out on trapiches writing about the crystallography, but I didn't really think about the lack of portraits of crystals to refer to. The cross-section of the aquamarine trapiches is perfectly hexagonal. Both of the Van Pelt gemmy emerald crystals (maybe they are the same crystal) are nearly round - am I missing something or has it been rounded?

I look forward to any images which members post in answer to Jim's inquiry!

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Matt_Zukowski
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PostPosted: Feb 26, 2010 17:59    Post subject: Re: best examples of trapiche emerald crystals?  

Although I don't have a picture, I was shown a large gemmy trapiche emerald at this year's Tucson. If memory serves, it was 5-7 cm long and 1-2 cm perpendicular to the c axis. The gemmy regions were really gemmy and saturated in color.
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PostPosted: Feb 26, 2010 20:30    Post subject: Re: best examples of trapiche emerald crystals?  

Hi Matt,

Was the specimen polished in any way to highlight the trapiche effect?

Thanks,

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simonoff




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PostPosted: Feb 26, 2010 20:55    Post subject: Re: best examples of trapiche emerald crystals?  

Here is one from the Smithsonian.


trapiche.JPG
 Description:
Trapiche from the smithsonian
 Viewed:  24607 Time(s)

trapiche.JPG


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PostPosted: Feb 26, 2010 21:03    Post subject: Re: best examples of trapiche emerald crystals?  

simonoff wrote:
Here is one from the smithsonian.

Excellent photo -- thanks for sharing. Any approximate dimensions of this specimen?

Cheers!

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PostPosted: Feb 26, 2010 21:10    Post subject: Re: best examples of trapiche emerald crystals?  

Very approximate maybe 2.5 inches (6.3 cm) across.

No problem

I am thinking of going back very soon - if you need something else in the picture, let me know.
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PostPosted: Feb 26, 2010 22:46    Post subject: Re: Best examples of trapiche emerald crystals?  

No, it was not polished in any way. It was in pretty good shape as a mineral specimen.
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PostPosted: Dec 03, 2015 15:17    Post subject: Re: Best examples of trapiche emerald crystals?  

For those interested in trapiche emeralds, the lead article of the last issue of Gems & Gemology (Fall 2015, Vol. 51, No. 3) gives a full update on this fascinating crystal habit.
Gérard
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PostPosted: Dec 06, 2015 08:47    Post subject: Re: Best examples of trapiche emerald crystals?  

hi,
I see I'm not the only one to admire Trapiches emeralds.
I saw 4 beautiful Trapiches at the last Munich Show.
I photographed under cross-polarized light one of them. We discover the crystal growth lines. Crystallization is one of the simplest methods to purify a mineral. The impurities are rejected in front of the solid phase taking shape.
This emerald comes from Muzo, Colombia. While other Muzo trapiches have rejected feldspars, this one had ejected carbonaceous impurities, always abundant in this Muzo shale.
That's what I think, do you?
Roger.



005-Trapiche_10256_R.jpg
 Mineral: Emerald - trapiche emerald
 Locality:
Muzo mining district, Western Emerald Belt, Boyacá Department, Colombia
 Description:
 Viewed:  19659 Time(s)

005-Trapiche_10256_R.jpg



006Trapiche_emerald_10260_R.jpg
 Mineral: Emerald - trapiche emerald
 Description:
 Viewed:  19682 Time(s)

006Trapiche_emerald_10260_R.jpg



007-Trapiche#1-refl_L - A_R.jpg
 Mineral: Emerald - trapiche emerald
 Description:
reflected light
X 6
 Viewed:  19661 Time(s)

007-Trapiche#1-refl_L - A_R.jpg



008-Trapiche#1-XPOL_001 - XPol-A_R.jpg
 Mineral: Emerald - trapiche emerald
 Description:
Under XPol Light
 Viewed:  19648 Time(s)

008-Trapiche#1-XPOL_001 - XPol-A_R.jpg



009-Trapiche#1-XPOL_001 - XPol-B_R.jpg
 Mineral: Emerald - trapiche emerald
 Description:
x12
 Viewed:  19636 Time(s)

009-Trapiche#1-XPOL_001 - XPol-B_R.jpg



010-Trapiche#1-XPOL_001 - XPol-C_R.jpg
 Mineral: Emerald - trapiche emerald
 Description:
x 32
 Viewed:  19622 Time(s)

010-Trapiche#1-XPOL_001 - XPol-C_R.jpg


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Elise




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PostPosted: Dec 07, 2015 15:24    Post subject: Re: Best examples of trapiche emerald crystals?  

Fiebre Verde wrote:
For those interested in trapiche emeralds, the lead article of the last issue of Gems & Gemology (Fall 2015, Vol. 51, No. 3) gives a full update on this fascinating crystal habit. Gérard

The entire issue is freely available online as a pdf via links here: https://www.gia.edu/gems-gemology (link rectified by the moderators).
I loved the article which I think will become quite an important classic reference. I did have some comments which I emailed to the journal as a Letter to the Editor today. With John S. White's encouragement, I'll share part of the letter here:

"I was very interested in the authors’ trapiche nomenclature discussion in Box A (page 224). I understand the desire to distinguish sectoral zoning formed by inclusions or texture as “trapiche-like;” the trapiche pezzottaite reported in this same issue probably falls under that category (Skalwold and Koivula, pages 326-328). However, I would argue that cordierite-indialite intergrowths known as “cherry blossom stones” included by the authors’ as “trapiche-like” actually qualify as true trapiche growth on the basis that each sector is the result of individual crystal growth. These unique trapiches are the result of a very complex indialite cordierite intergrowth phenomenon in which cordierite crystals grow epitaxially on the six prism faces of an indialite crystal. The latter’s remaining faces continue to grow and later alter to cordierite while grains of this intergrowth’s host accumulate along the sectors, forming the trapiche appearance. The indialite later alters to cordierite and eventually the entire intergrowth is replaced by muscovite, while retaining the outward appearance of the original mineral intergrowth; a fascinating example of a pseudomorph (see Rakovan, J., Kitamura, M., Tamada, O.( 2006). Sakura Ishi (cherry blossom stones): complex cordierite-indialite intergrowths from Kameoka, Kyoto Prefecture, Japan. Rocks & Minerals, 81(4): 284-292 and Kitamura, M. and Yamada, H. (1987). Origin of sector trilling in cordierite in Daimonji hornfels, Kyoto, Japan. Contributions to Mineral Petrology, 97: 1-6).

Also, in Dr. Nassau’s defense (page 232) I would add that he corrected the locality information stated in his original Spring 1970 American Mineralogist paper in a following issue published during the Fall of the very same year: “Based on information by E.J. Tripp and C.H. Hermandez and E.J. Tripp (private communication) the actual origin of the trapiche emeralds attributed to the Chivor Mine is the Peñas Blanca mine near Muzo, Colombia. These have a clear center and are distinct from specimens from Muzo itself which have a dark center. Most Peñas Blanca trapiche emeralds are purchased and distributed by Mr. W.F. Bronkie the manager of the Chivor mine and were accordingly attributed to the Chivor Locality” (Nassau, K. and Jackson, K.A. (1970) Trapiche emeralds from Colombia: Correction. American Mineralogist, 55 (10):1808-1809). This erratum by the authors themselves is overlooked throughout later literature referencing their paper; I always look for it in hopes that it will surface and hope you will re-print it."

I wondered what FMF members thoughts are regarding trapiche nomenclature. Roger, your photographs are really wonderful; I especially like the one in x pol light. Thank you for sharing!

Best wishes,
Elise

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Val




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PostPosted: Dec 08, 2015 17:27    Post subject: Re: Best examples of trapiche emerald crystals?  

Unique and exquisite Emerald specimen. An Emerald crystal with a scepter of an actual trapiche Emerald crystal and all gem. What a wonderful thrill to be the current care taker of this natures creation.

I have seen Trapiche sharp emerald crystals. I have a fairly large (3-4 cm. in length) and dark colored one that I will have to find in the collection and photograph. Usually they are sliced up for gem cabochons and rarely get offered for collectors of the complete crystal. My son lives in Bogata, Colombia for 15 years, involved in specimen procurement.



EmeraldTrapSceps-l1600a.jpg
 Mineral: Beryl (variety emerald)
 Locality:
Muzo mining district, Western Emerald Belt, Boyacá Department, Colombia
 Dimensions: 2.05 cm x .91 cm x .84 cm
 Description:
 Viewed:  19425 Time(s)

EmeraldTrapSceps-l1600a.jpg



EmeraldTrapSceps-l1600 (2b).jpg
 Mineral: Beryl (variety emerald)
 Locality:
Muzo mining district, Western Emerald Belt, Boyacá Department, Colombia
 Dimensions: 2.05 cm x .91 cm x .84 cm
 Description:
 Viewed:  19435 Time(s)

EmeraldTrapSceps-l1600 (2b).jpg



EmeraldTrapSceps-l1600 (2).jpg
 Mineral: Beryl (variety emerald)
 Locality:
Muzo mining district, Western Emerald Belt, Boyacá Department, Colombia
 Dimensions: 2.05 cm x .91 cm x .84 cm
 Description:
 Viewed:  19412 Time(s)

EmeraldTrapSceps-l1600 (2).jpg



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Fiebre Verde




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PostPosted: Dec 09, 2015 15:26    Post subject: Re: Best examples of trapiche emerald crystals?  

Roger Warin wrote:
hi,
I see I'm not the only one to admire Trapiches emeralds.
I saw 4 beautiful Trapiches at the last Munich Show.
I photographed under cross-polarized light one of them. We discover the crystal growth lines. Crystallization is one of the simplest methods to purify a mineral. The impurities are rejected in front of the solid phase taking shape.
This emerald comes from Muzo, Colombia. While other Muzo trapiches have rejected feldspars, this one had ejected carbonaceous impurities, always abundant in this Muzo shale.
That's what I think, do you?
Roger.


Roger, I can only second what Elise mentioned about your photographs. Please share more!
Regarding your comment about the rejected impurities - I guess all depends on the nature of the impurities found during the growth of the trapiche.
Muzo is best known for its high concentration of carbonaceous impurities but other type of impurities can also occur in the growth process. Not only feldspar (albite) but also monazite, K-feldspar (presumably adularia), epidote, apatite and zircon (Ohnenstetter & al., 1998 - Emeraudes Trapiches Colombiennes, L'Emeraude, Association Française de Gemmologie)
Gérard
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marco campos-venuti




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PostPosted: Dec 10, 2015 18:59    Post subject: Re: Best examples of trapiche emerald crystals?  

What about this?


IMG_1011 (Medium).JPG
 Mineral: Emerald trapiche crystal, Tucson 2011
 Locality:
Muzo mining district, Western Emerald Belt, Boyacá Department, Colombia
 Description:
 Viewed:  19227 Time(s)

IMG_1011 (Medium).JPG


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Roger Warin




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PostPosted: Dec 11, 2015 03:25    Post subject: Re: Best examples of trapiche emerald crystals?  

It’s time to listen a master of crystallography.
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PostPosted: Dec 11, 2015 03:34    Post subject: Re: Best examples of trapiche emerald crystals?  

Thank you very much Elise, Gerard.

The word Trapiche has its origin in the name of ore grinding rolls in South America. It's a geological concept, perhaps earlier.
Isabella Pignatelli and all describe the phenomenon very well.

As the birefringence of emerald is very small, I used a trick to increase the retardation and thus accentuate colorations.
A gypsum plate is inserted between the trapiche and the polarizing filter. Its function is to add a known retardation. Gypsum produces a 550 nm red retardation.
This view is with the gypsum plate inserted most areas shift to first order yellow whereas a few shift to low second-order blue color.
Of course the sample is not a thin section. Its thickness is 4 mm.
Just for fun.
Roger.



Trapiche&gypse-B_R.jpg
 Mineral: Emerald - trapiche emerald
 Dimensions: thickness = 4 mm
 Description:
With a gypsum plate
 Viewed:  19089 Time(s)

Trapiche&gypse-B_R.jpg


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NellsRocks




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PostPosted: Dec 11, 2015 16:26    Post subject: Re: Best examples of trapiche emerald crystals?  

Forgive my newbie question, but these photos look a LOT like our local chiastolite. Can anyone explain in simple terms how these "patterns" are formed?
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