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 Post subject: Scapolite vs. Heliodor vs ???
PostPosted: Wed Feb 12, 2020 12:46 am 
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I purchased some "unknown" facet rough recently that I thought looked like it was probably Yellow Scapolite. I've only ever seen photos of Scapolite before, and didn't really know anything about it... so I figured it was worth a little bit of a gamble to add it to my assortment of rough if that is what it was.

So now that I have it here, I want to confirm what type of crystal it is before cutting it. I think I've got it narrowed down to 2 possibilities (Scapolite or Heliodor/golden beryl), but I'm still not sure. My measurements point more towards Beryl, but I've never seen a beryl crystal that looks like these ones before(I have a lot of Aquamarine/Emerald/Morganite/Goshenite, but no Heliodor).

Here is what I have so far:
SG = 2.71
RI =1.565-1.570
Birefringence =.005 (this one was hard to know for sure, it may be a bit higher)
Optic Character/sign = Uniaxial (-)
Color = Yellow
Luster = Vitreous
Dichroism = maybe very weak? yellow/lighter yellow
Note: I polished a single facet on one crystal using a CeO ultralap, and it worked pretty well.

My measurements probably have some error, as I still don't have a lot of practice with the refractometer, but I'm sure I'm pretty close.

So what do the experts here say? is it probably Scapolite as I'm assuming right now? Could it be Beryl like the data shows? or is it something else entirely that I don't have on my list of possible materials?


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 Post subject: Re: Scapolite vs. Heliodor vs ???
PostPosted: Wed Feb 12, 2020 3:39 pm 
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Apparent cleavage. Kinda rules out beryl, right, Stephen?


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 Post subject: Re: Scapolite vs. Heliodor vs ???
PostPosted: Thu Feb 13, 2020 3:08 am 
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Fluorescence? Yellow scapolite often fluoresces red, pink or orange under UV light. Some references say under LWUV. My Tanzanian yellow scapolite fluoresces more strongly under SWUV. Yellow beryl should be inert under UV.


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 Post subject: Re: Scapolite vs. Heliodor vs ???
PostPosted: Thu Feb 13, 2020 7:33 am 
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Hardness test should tell you, scapolite is much softer than beryl.

Jim


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 Post subject: Re: Scapolite vs. Heliodor vs ???
PostPosted: Thu Feb 13, 2020 11:49 am 
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The heavy etching on these crystals does make sight ID harder. I haven't seen scapolite take on this kind of form, though never say never on that. I'm not 100% sure about the cleavage, it might just be a weird fracture, or an expression of beryl's own weak cleavage? A very odd parcel.
Either way these look like small, beautifully scultured crystals. If scapolite or beryl they are worth more as is than if faceted--golden beryl and scapolite are routinely available in big chunky pieces for friendly prices.

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 Post subject: Re: Scapolite vs. Heliodor vs ???
PostPosted: Thu Feb 13, 2020 4:10 pm 
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As Duncan, I would use fluorescence to separate the 2 options.


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 Post subject: Re: Scapolite vs. Heliodor vs ???
PostPosted: Thu Feb 13, 2020 4:20 pm 
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Mike, you could always send a wee bit to me or Stephen and we could test it with a raman.


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 Post subject: Re: Scapolite vs. Heliodor vs ???
PostPosted: Thu Feb 13, 2020 11:53 pm 
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Thanks for the additional test ideas! I didn't even think about fluorescence... but I don't have a SWUV light. the closest I have is a very weak long wave "black light".

I did check with the LWUV light I have, and didn't get any sort of reaction (although the post-it notes I had nearby lit up nicely). This may indicate it's not Scapolite per your comments

Next was on to the hardness testing:
Quartz would not scratch it, but it would scratch quartz (this probably rules out Scapolite).
Topaz would not scratch it, and it would not scratch the Topaz. (I guess this could be on the high end of hardness for Beryl).

So, it looks like all measurements still point to Beryl (and I don't have anything else on my list of possibilities). They are just perhaps the most unusual Beryl crystals I have ever seen before.

Stephen: I'd love to find some big chunky pieces of Golden Beryl or Scapolite at "very friendly prices"!

Barbra: How big is a "wee bit"? I'd be happy to send a small piece to confirm 100% if my testing is indeed conclusive.

And on a related note... I'm not too familiar with the Raman (other than I know I'd love to have one, and cant afford one). Can it determine copper content of Tourmaline? I have a small slice of tourmaline that I've been saving to eventually test(possibly with the Mass Spectrometer when I have access). I was told this material is copper bearing when I bought it years ago. I cut a couple nice stones from it that I think could be amazing if it's copper bearing and I heat treat it(they are fairly dark now with purple/orange/brown colors). I saved some small sections when I cut the stones in case destructive testing was required(or easier/cheaper). Unfortunately, if it looks like it is worth heat treating.... I'll need to buy a burn out oven LOL


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