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 Post subject: Re: My Mexican Amber article
PostPosted: Mon Mar 21, 2011 12:20 pm 
davegibson wrote:
Jan, I would not describe copal as a gem.
Just looked in Robert Websters book Gems, their sources description and identification. No mention of copal as a gem.


Try 6th Edn, p 648. Copal is described as 'an intermediate state between fresh plant resin and Amber' and as an common 'Amber imitant'. Various tests for discriminating the one from the other are given.


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 Post subject: Re: My Mexican Amber article
PostPosted: Mon Mar 21, 2011 2:48 pm 
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Hey Yeti, That's a wonderful red piece there...was there much red brought out this season in Simojovel?

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 Post subject: Re: My Mexican Amber article
PostPosted: Mon Mar 21, 2011 5:14 pm 
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Hi everyone :)
Kerensky regards, Robert Websters book Gems 6th Edn,
He does not describe Copal as a gem :roll:

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 Post subject: Re: My Mexican Amber article
PostPosted: Mon Mar 21, 2011 9:47 pm 
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Hi Kirk

Not much (but some) from what I saw in the catalogue, if you go on AmbermineMexico website you'll get an idea of their stock (my supplier) but they uploaded a new catalogue to me when i was ordering so the website is not totally current.

I had the shipment sent "in country" to Puerto Vallarta where i was vacationing and believe me it was an "adventure" just getting the shipment.

regards/Yeti


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 Post subject: Re: My Mexican Amber article
PostPosted: Tue Mar 22, 2011 7:38 am 
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Hi everyone :)
Yeti, can not make out what type of insect is in your amber. It seems to have two wings. so Deptera, some kind of long legged fly.how big is the insect? Just wonderd if you bought
the piece at the Lagunilla Sunday market Mexico city. You can find genuine Chiapas amber there. but In the zocalo round the Cathedral, what the vendors have there is just about all polystyrene plastic. It as about the same S.G as amber. and will flout in a salt water solution

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 Post subject: Re: My Mexican Amber article
PostPosted: Tue Mar 22, 2011 8:25 am 
davegibson wrote:
Hi everyone :)
Kerensky regards, Robert Websters book Gems 6th Edn,
He does not describe Copal as a gem :roll:


Not stated but implied? My understanding of it is that an 'imitant' is one of the following:

1. An artificial substance fashioned to imitate, casually, a gemstone. E.g. CZ or paste can be Diamond imitants.

2. A lesser gemstone presenting casually as a more valuable one. E.g. red Spinel for Ruby or Zircon for Diamond.

3. A composition stone of some combination of artificial material, less valuable gem material and, sometimes, small quantities of the 'real' gem, fashioned so that the whole presents to casual observation as the 'real' gem. Doublets etc.

It's hard (for me at least) to place Copal in any other category other than 2. Copal is of natural formation and has beauty, durability and some rarity. It's just not as desirable as the Amber that time alone will, one day, transform it into.


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 Post subject: Re: My Mexican Amber article
PostPosted: Tue Mar 22, 2011 9:38 am 
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Hi again Dave,

Thanks for looking.

This piece was purchased at a Sunday market in la cruz de huanacaxtle in Nayarit, the insect is visible to the eye and about 3mm in its curled up position so would probably be about 4mm stretched out. The spiked hind legs seem extremely long in proportion to the rest of the body, they appear to be 3-4mm also, he must have been quite a jumper plus a flier and i can imagine once he grabbed onto something, he would be very difficult to dislodge.

(The Chiapas? is 4.6cm by 3cm and 10-12mm thick.)

At the market, i looped it and it looked real and (i felt) there were just too many inclusions (black matter etc.) to be a replica, (but who knows) plus it had that warm smooth amber feel. I read somewhere that amber gets a brownish hue when in the sunlight for a long time, i believe this may be the case with this piece. The original necklace had about 10 pieces strung with this being the focal point.

Anyway, the first thing I did was the float test when i got home, it sunk in water and floated with the salt solution. I did a scratch test and looped the scratch, it had the nice splintering at the scratch edges when viewed under a 20x loop. Also, it has the (inconvenient for specimen viewing) internal flow line/fracture inclusions that seem to accompany chiapas, lastly i put the sandpaper to a section and it powdered nicely, and smelled right... i then polished the section and it came up perfectly...so (i think) it's real, nevertheless I ordered the Poinar and Poinar Amber Forest book and am hoping to see a specimen that matches up that would validate it if he's
extinct.

I'll post a follow up once i receive the book.

regards/yeti


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 Post subject: Re: My Mexican Amber article
PostPosted: Tue Mar 22, 2011 3:28 pm 
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Yeti wrote:
Hi Kirk

Not much (but some) from what I saw in the catalogue, if you go on AmbermineMexico website you'll get an idea of their stock (my supplier) but they uploaded a new catalogue to me when i was ordering so the website is not totally current.

I had the shipment sent "in country" to Puerto Vallarta where i was vacationing and believe me it was an "adventure" just getting the shipment.

regards/Yeti


Yah, Mexican Postal services can be a laugh...or cry...

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 Post subject: Re: My Mexican Amber article
PostPosted: Wed Mar 23, 2011 1:32 pm 
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davegibson wrote:
Jan, I would not describe copal as a gem.
Just looked in Robert Websters book Gems, their sources description and identification. No mention of copal as a gem.


Kerensky: It is not described as a gem in Websters third edition. You have the sixth edition Gems edited by Michael O'Donoghue. It seems he has rephrased that paragraph.
Under Synthesis and Simulation
Webster describes copal as a recent fossil resin. It is the most important of the natural ambers imitations.

I would not describe copal as durable

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 Post subject: Re: My Mexican Amber article
PostPosted: Wed Mar 23, 2011 5:07 pm 
davegibson wrote:
davegibson wrote:
Jan, I would not describe copal as a gem.
Just looked in Robert Websters book Gems, their sources description and identification. No mention of copal as a gem.


Kerensky: It is not described as a gem in Websters third edition. You have the sixth edition Gems edited by Michael O'Donoghue. It seems he has rephrased that paragraph.


Dave,

I have both the 3rd edn (a 1975 print of Webster's personal last edn, complete with it's few endearing errors, omissions and anachronisms) and the 6th edn. The 6th is not so much a titivating edition (as, perhaps, were Anderson's 4th and Read's 5th edns). Rather, in the 6th M.O'D excised much to be found even in the 5th edn, and introduced much new material written by both himeslf and other luminaries. Without that radical surgery, 'Gems' would by now be fit to considered asnother history book. As it is, those fortunate enough to have a copy of both the 3rd and 6th editions have for reference the sweep of gemology and the best gemologist thinking from its early beginnings up to the late 90's. In another thread, some of us traced some rather quaint advice (still followed by some) given by Webster in 'Gems' on the protection in storage of glass hemi-cylinders back through earlier works, possibly to it's origination in the early 1920's when the advice was likely to have been more appropriate that it seems now, getting on for a century later. All that said, Webster's voice echoes yet through much of the 6th edn.

But returning to consideration of Copal..... It seems widely agreed that there is both fossilised Copal and sub-fossil Copal, so perhaps that is too great a sweep for general statements about the gem-worthiness of 'Copal' to be usefully made from any side? Guenther's 'Tables of Gemstone Identification' lists Copal (next to Amber). GEMSDAT also lists it, giving as a source of (fossilized?) Copal's gemmological characteristics, 'The Journal of Gemmology 1997 Vol 25, N°6, p408-416'. That reference, is of course, just nine years earlier than publication of the 6th edn of 'Gems' :D

Regards,
Owen


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 Post subject: Re: My Mexican Amber article
PostPosted: Thu Mar 24, 2011 8:07 am 
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Yeti wrote:
I read somewhere that amber gets a brownish hue when in the sunlight for a long time, i believe this may be the case with this piece.


Amber gets brown over time not primarily by sunlight but by oxidising from the air contact. I once made a knife with handle from amber. IIRC it was around 1985. When new it was bright bright yellow. Now 25 years later the handle is more orangeish. It has been stored out of sunlight for 99% of this time. It is also set in a sheath which covers 2/3 of the handle. The oxidising has occurred also on this part.

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 Post subject: Re: My Mexican Amber article
PostPosted: Thu Mar 24, 2011 11:36 am 
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re:knife handle

Interesting, so the handle oxidization would be a "skin" that would polish clear again or does it 'sink in'?

If the former, I could perhaps assume that my insect piece is "brownish" throughout and may have nothing to do with age since mined as i did a test sand to a section (bottom left shoulder) and the hue was constant before and after.

(Pic is shown with sunlight background.)


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 Post subject: Re: My Mexican Amber article
PostPosted: Fri Mar 25, 2011 4:42 pm 
Conny Forsberg wrote:
Yeti wrote:
I read somewhere that amber gets a brownish hue when in the sunlight for a long time, i believe this may be the case with this piece.


Amber gets brown over time not primarily by sunlight but by oxidising from the air contact. I once made a knife with handle from amber. IIRC it was around 1985. When new it was bright bright yellow. Now 25 years later the handle is more orangeish. It has been stored out of sunlight for 99% of this time. It is also set in a sheath which covers 2/3 of the handle. The oxidising has occurred also on this part.


I have a Yemeni khanjar with a gold-adorned carved Amber (or Copal) hilt that has done exactly the same (over 40 years). So glad to know that the same happens to others :)


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 Post subject: Re: My Mexican Amber article
PostPosted: Fri Mar 25, 2011 5:32 pm 
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Owen, actually I like the tone of the aging amber better than the freshly polished yellow. Wish the same could be said about my own ageing :)

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 Post subject: Re: My Mexican Amber article
PostPosted: Fri Mar 25, 2011 7:42 pm 
Conny Forsberg wrote:
Owen, actually I like the tone of the aging amber better than the freshly polished yellow. Wish the same could be said about my own ageing :)


:lol:
Fashion it thus. Nothing in the body improves in performance past the age of 21. OTOH, mental performance often continues to improve for decades thereafter - for those who are willing to continue learning :D One of the nice things about GO is the number of those hanging out here who fall in that latter category.

Back to Amber. All this has provoked me to unearth my khanjar annd do some tests on its hilt.


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