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 Post subject: Stephen Challener's Curiosities
PostPosted: Fri Feb 10, 2017 2:53 pm 
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Location: San Francisco
Indonesian Green Chalcedony First in a Series
Weight: 1.84 carats
Opaque with Semi-translucent edges
GemmoRaman Scan identifies the material as quartz because the peak at 501cm -1 is negligible. (if anyone is interested I will send you the scan). Chalcedony is defined as the intergrowth of hydrogenated nanometer sized low quartz and moganite proven by a distinct peak at 501cm -1 . The polariscope indicates the material to be chalcedony, not quartz as the semi translucent edges remain light at ll times when rotated.
I ran a Photoluminescent scan to see if I could detect chromium. None detected.
But, some very interesting inclusions visible at 20x magnification:
I suspect, they are pseudo hexagonal biotite.
Stephen you want to weigh in?
Image
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Green Emerald Cut Gem sold as Demantoid Second in our series
Weight: 0.47 ct,
Polariscope: Singly refractive
GemmoRaman: Grossular Tsavorite slam dunk
Inclusion Scene: Liquid veiling typical of grossular
Image

European Jade :shock: Third in our series
Weight: 5,51 carats
Polariscope: Aggregate
UV: no reaction
GemmoRaman: Green Chalcedony...now there's a shocker :wink:
Pretty stuff:
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 Post subject: Re: Stephen Challener's Curiosities
PostPosted: Sun Feb 12, 2017 12:39 am 
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Hello,
Thank you so much for looking at these! Let me give a bit of background on the pieces now that I am back from Tucson.
The green chalcedony was a facebook purchase--many people here will likely have seen these various offerings from Indonesian sellers, largely chalcedonies of various sorts but also opals and amber--some natural-looking and some very questionable. I wanted to buy some purple chalcedony, and this seller was offering a few other things as well. Some were obvious trash (like a big pile of cherry-red "carnelian" with suspiciously shiny, conchoidal fractures:
Image
But he was also offering some more promising-looking green chalcedony, which I didn't save pictures of. It showed a nice even translucency and a sort of chromium-green color:
Image
I decided I wanted some of that too! What I got, however, was just a tad different from pictures. It was almost entirely opaque, with a banded dull green color and only a thin rind of more translucent green. I managed to cut a little slice off the edge and cut a few cabs. To say the least it wasn't what I had ordered, but on the plus side he had sent me something which is no guarantee with these kinds of purchases, and the purple chalcedony was pretty nice. I suspect the hexagonal-looking inclusions are actually pyrite showing their less-common dodecahedral crystal structure, based on some slightly larger patches in other areas of the rough.

The tsavorite is an odd case--the seller had some rough and cut stones. I had previously purchased rough and the RI pointed to grossular, but it was an odd circumstance because he was normally quite reliable, and while he was selling it as demantoid he was pricing it more like hessonite. I really appreciate you verifying that for me!

The "european jade" was being sold by a Chinese dealer on eBay--most of his other offerings were bad carvings so it stood out.
Sorry to say I only have the thumbnail: Image
It looked and cut like chrysoprase but it was another contextually odd sale and I wanted to be sure. The white inclusions didn't go in at all, nice gel center, and it cost one penny (plus 8 dollars shipping but why bring that up).

The indonesian chrysoprase has been hitting facebook pretty hard recently. It is always sold backlit because this makes it look amazing:
Image
Its actual color is fairly light. It looked fairly promising when I got it, with a rich light green color, amazing translucency and optical continuity, and a morphology very reminiscent of chrysoprase from other locales:
Image
It also had a waxy, subconchoidal fracture unlike the highly glossy fracture I had seen on a chrysopal from Kazahkstan. However, I was soon to rethink my opinion when I put it on the saw--it cut like butter, while solid agate or chalcedony generally cuts like... well, chalcedony. However, when I actually trimmed out an oval, dopped it up and cut it it ground much more slowly than most opals I had dealt with; one might call it downright agatesque. Also, sometime during cutting it decided it wanted to be opaque:
Image
So I wasn't sure what to make of that--clearly it isn't proper chrysoprase but it isn't chrysopal as I know it either.
Tremolite is a bit of a surprise, though. I wonder if it's a mix of very non-crystalline opal with a bit of tremolite helping with the color?
One way or another, I wouldn't recommend buying this material unless maybe you're a carver.

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 Post subject: Re: Stephen Challener's Curiosities
PostPosted: Wed Mar 01, 2017 5:29 pm 
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Indonesian Chrysoprase Fourth in our series
Weight: 4.64 carats
Polariscope: Aggregate
UV: No reaction
Hardness 5+; 6-
RI: possible spot reading ≈ 1.65
GemmoRaman: Inconclusive very weak match to actinolite.....
Ran everything again and I'm till coming up with a very weak match for actinolite.
SG useless as there is too much of a matrix material.
Image

Skardo Emerald Fifth in our series
Weight: 10.17 carats
Polariscope: Doubly refractive
UV: Faint red
RI: 1.56 looking down the "C" axis
GemmoRaman: Beryl
Photoluminescent Spectrum: Emerald Green: Cr3 peaks at 680.6 and 683.6nm

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Madagascar Emerald Sixth in our series
Weight: 4.28 carats
Polariscope: Doubly refractive
UV: inert
GemmoRaman: Beryl
Photoluminescent Spectrum: (As before) Emerald, Green: Cr3 peaks at 680.6 and 683.6nm

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 Post subject: Re: Stephen Challener's Curiosities
PostPosted: Wed Mar 01, 2017 5:58 pm 
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Sorry about the small piece on that one--I used my band saw to cut a bit off the edge on the off chance heat from my main saw was causing the change in opacity on the original piece. I have a finer blade now that definitely won't have issues, and I'd be happy to send a bigger piece to you or anyone else.

I'm thrilled the Skardu emerald is really emerald! The color shifts a bit from light to light. I wonder if these are related to the clean, light toned skardu emeralds that one seller had this year. Cool about the madagascan too of course but the skardu material was less expected.

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 Post subject: Re: Stephen Challener's Curiosities
PostPosted: Wed Mar 01, 2017 7:18 pm 
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Say What? Seventh in our series
Opaque, Metallic cabochon
Weight: 35.34 carats
What I know it is not: Silver, Gold or Platinum (acid testing)
Not magnetic: so we know it is not an iron ore
SG: 7.17
Streak: Steel gray
With magnification, there appears to be small metallic yellow portions within metallic gray portions.
I'll go out on a limb here: galena and pyrite cabochon ??? Stephen, what did you buy here?

Image

And, I'll package your loot to send back within the next couple days. :D


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 Post subject: Re: Stephen Challener's Curiosities
PostPosted: Wed Mar 01, 2017 8:06 pm 
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It is cobaltite in calcite matrix from Canada. It sometimes has native silver plumes mixed in, so one always hopes!

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 Post subject: Re: Stephen Challener's Curiosities
PostPosted: Wed Mar 01, 2017 8:44 pm 
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I'll go wash my hands, just in case....
Geeze I don't have instrumentation to identify that obscure stuff.
But, it is cool to see it.
The higher SG could be the result of the silver.


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