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Author Topic: Unknown material  (Read 261 times)

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VegasJames

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Unknown material
« on: October 28, 2018, 01:56:38 PM »

Have not made a positive ID on this material yet. Will be sending it in shortly for testing. It is very hard. Cannot scratch is with a pure quartz crystal but I was able to make a tiny scratch in the quartz crystal with it. The color varies from light green to dark green and even dark blue-green. There is traces of turquoise running through some of the material.

DSC_0803 by James Sloane, on Flickr
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southerly

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Re: Unknown material
« Reply #1 on: November 01, 2018, 08:53:23 PM »

If it is really tough it may be peridotite or an associated pyroxene mix.
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VegasJames

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Re: Unknown material
« Reply #2 on: November 01, 2018, 09:17:19 PM »

If it is really tough it may be peridotite or an associated pyroxene mix.

Thanks. I checked the hardness of peridotites though and they area hardness of only 5.5 to 6. This has a hardness of around 7 as quartz will not scratch it but it can barely scratch a quartz crystal.
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hummingbirdstones

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Re: Unknown material
« Reply #3 on: November 02, 2018, 06:52:57 AM »

Has an almost rainforest jasper look to it.  Please let us know what the outcome is when you have it tested.
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Robin

VegasJames

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Re: Unknown material
« Reply #4 on: November 02, 2018, 10:24:43 AM »

Has an almost rainforest jasper look to it.  Please let us know what the outcome is when you have it tested.

Hopefully I will be sending it off to GIA shortly. I need to make a small ca if it under 20 carats. Normally I do mot do small cabs since I dom't use a dop stick. A soon as I can get that done and make a couple of cabs of suspected turquoise to send off I will get them off to GIA.
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lithicbeads

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Re: Unknown material
« Reply #5 on: November 03, 2018, 08:10:36 AM »

lapilli metatuff ?
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VegasJames

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Re: Unknown material
« Reply #6 on: November 03, 2018, 11:20:49 AM »

lapilli metatuff ?

No idea. I did send it off for XRD testing in New Mexico. They came back with 50% quartz and 50% sanidine, which makes no sense since the 50% sanidine would reduce hardness. Sanidine is only a hardness of 6 and brittle. This stone can scratch a quartz crystal and is not brittle at all.

Of course this is the same lab that I had some turquoise blue stones tested and they came back with 100% malachite on two of the stones and 98% malachite and 2% quartz on the third. Since malachite does not occur in blue I have serious doubts about their testing or I have the rarest malachite on Earth.
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lithicbeads

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Re: Unknown material
« Reply #7 on: November 03, 2018, 01:30:03 PM »

If the sanidine sorce was volcanic like a rhyolite it very well could be a tuff. We have lots of them in the northwest but it also looks  more than a bit like a local very rare rock keratophyre with a very similar structure and color.
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VegasJames

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Re: Unknown material
« Reply #8 on: November 03, 2018, 02:35:29 PM »

If the sanidine sorce was volcanic like a rhyolite it very well could be a tuff. We have lots of them in the northwest but it also looks  more than a bit like a local very rare rock keratophyre with a very similar structure and color.

A tuff would not have a hardness of 7+.

How about the keratophyre. Is it at least a 7 in hardness?
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lithicbeads

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Re: Unknown material
« Reply #9 on: November 03, 2018, 04:16:37 PM »

Tuff is a strange beast.You can carve many tuffs with your fingernail but in 40 years of cutting the hardest stone I ever found was a piece of tuff below Glacier peak. It had an open structure  and with magnification almost resembled a cheese grater in texture.As for hardness it was off the charts harder than any chert or porcelain jasper I have ever cut and noticeably so.I think geology makes weirder things at times than we can imagine.
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