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 Post subject: Spodumene??
PostPosted: Tue Nov 29, 2011 9:36 pm 
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These were found, buried, in Southern California. I did the acid test, not a form of Calcite. Thinking it's possibly Spodumene? It's brittle, dark smoky green to yellow in color, translucent in some areas, and flat in some areas, some pieces have irridecent flashes.

Here is a bunch of photos I took:
http://s231.photobucket.com/albums/ee31 ... e/Crystal/

I know It's difficult to tell from photos, but any ideas would help :)

-Deeni


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 Post subject: Re: Spodumene??
PostPosted: Wed Nov 30, 2011 6:47 pm 
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no one has any ideas? thoughts? opinions? :(


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 Post subject: Re: Spodumene??
PostPosted: Wed Nov 30, 2011 11:58 pm 
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deeni wrote:
no one has any ideas? thoughts? opinions? :(
Hi Deeni, working in the field has me become even more cautious as to relating my opinion when I don't have enough 'facts'. What we know so far, is a location, and photos showing some possibilities. Since you have the crystals in hand, it would be really helpful to acquire a specific gravity reading at the very least, and hopefully get at least one surface polished so a refractive index reading can be rendered.

Then, it may be possible to isolate some possibilities.

I am sorry to report, that as a general rule, gemologists are not risk takers when it comes to laying out their opinions.

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 Post subject: Re: Spodumene??
PostPosted: Tue Dec 13, 2011 4:59 am 
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Actually, these specimens do show quite a few characteristic features.
Just from looking at the pictures, it looks like it is gypsum: I can see pearly lustre, flaky habit, longitudinal cleavage, scratched surface (low hardness), let's also add gypsum is often found buried in the ground as was reported.
Of course some testing would be suitable so to confirm it: gypsum cannot scratch your finger nail but gypsum can be scratched with the finger nail.

Never underestimate the many clues you can get through a careful visual observation of both external and internal characteristics (first with the naked eye, and then with the loupe). This is especially true for rough minerals even more than for cut stones (notably, crystal shapes, cleavage and fracture are important). Also very helpful for identification of minerals are paragenesis (i.e. associated minerals), geological setting, and exact locality of origin. Of course, the more minerals you see the easier it gets.


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 Post subject: Re: Spodumene??
PostPosted: Thu May 03, 2012 3:34 pm 
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Gypsum was also the first thing to come to my mind: very similar looking specimen can be found in clay rich sediments here in Austria.

@Deenie can you find any kind of twinning like in this http://www.minerals.net/Image/7/70/Gypsum.aspx
crystall?

If you take a very thin plate cleaved from a crystall, can you bend it a little?

Another test for gypsum would be to put a small piece in a test tube and heat it from below. if water condenses in the cooler parts of the test tube this would also be a sign for the mineral in question beeing gypsum (gypsum contains water).

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 Post subject: Re: Spodumene??
PostPosted: Fri Oct 12, 2012 11:24 am 
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Looks like gypsum, which is very, very easy to identify:

Soft enough to be scratched by a fingernail.

Flexible but not elastic, (like mica); eg: you can bend it with finger pressure but it stays bent.

Perfect cleavage.

Water soluble.

Fun stuff to collect.


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 Post subject: Re: Spodumene??
PostPosted: Mon Oct 15, 2012 7:40 am 
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gypsum isn't water soluble


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 Post subject: Re: Spodumene??
PostPosted: Tue Oct 16, 2012 8:09 pm 
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"Gypsum is moderately water-soluble (~2.0–2.5 g/l at 25°C)[6] and, in contrast to most other salts, it exhibits a retrograde solubility, becoming less soluble at higher temperatures."

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 Post subject: Re: Spodumene??
PostPosted: Thu Dec 06, 2012 10:18 am 
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Then I guess it is indeed water soluble but very very slowly


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 Post subject: Re: Spodumene??
PostPosted: Thu Dec 06, 2012 2:51 pm 
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cascaillou wrote:
Then I guess it is indeed water soluble but very very slowly


As are we all :-)

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 Post subject: Re: Spodumene??
PostPosted: Thu Dec 06, 2012 5:37 pm 
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