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CranCowan
Joined: 28 Sep 2016
Posts: 18
Location: Hines
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 Posted: Sep 28, 2016 23:25 Post subject: Re: Please help identify this mineral/crystal. |
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| Sphalerite will dissolve in muriatic acid (HCl). It produces H2S gas which smells like rotten eggs. |
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Bob Harman
Joined: 06 Nov 2015
Posts: 765
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| Posted: Sep 29, 2016 07:45 Post subject: Re: Please help identify this mineral/crystal. |
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Sphalerite is a sulfide.....ZnS..... I thought CARBONATES dissolved in some acids such as muriatic acid (28% HCl). I never had a sphalerite show evidence of dissolving when I cleaned it.
Am I now right or wrong? BOB |
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geofossile
Joined: 29 Sep 2016
Posts: 10
Location: charleville mézières
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| Posted: Sep 29, 2016 07:59 Post subject: Re: Please help identify this mineral/crystal. |
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| rhichens wrote: | | Any help with identifying this mineral would be much appreciated. The whole specimen has a lovely sparkle that unfortunately doesn't show up in the photos. The surface in many places has a silver, almost glassy appearance. Some areas have a white or light grey powdery appearance. There are clusters of dark red crystals and areas of metallic, black crystals that may be galena. |
I think it is sphalerite. |
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CranCowan
Joined: 28 Sep 2016
Posts: 18
Location: Hines
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| Posted: Sep 29, 2016 08:05 Post subject: Re: Please help identify this mineral/crystal. |
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| Bob Harman wrote: | Sphalerite is a sulfide.....ZnS..... I thought CARBONATES dissolved in some acids such as muriatic acid (28% HCl). I never had a sphalerite show evidence of dissolving when I cleaned it.
Am I now right or wrong? BOB |
True, carbonates dissolve in HCl but so does ZnS (try it and see). The products are zinc chloride and hydrogen sulfide). It won't fizz like calcite but it should produce a stinky smell. |
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Pete Richards
Site Admin
Joined: 29 Dec 2008
Posts: 845
Location: Northeast Ohio
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| Posted: Nov 25, 2016 10:43 Post subject: Re: Please help identify this mineral/crystal. |
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The textbooks (Dana's System) confirm that sphalerite is soluble in hydrochloric acid with the evolution of hydrogen sulfide. This reaction may be a little bit slow for easy detection, but would be sped up with the use of warm hydrochloric acid applied to a powdered mineral sample. It might even fizz slightly, since hydrogen sulfide is a gas.
A further distinction is that sphalerite has very good cleavage in several directions, while garnet lacks cleavage, though it sometimes may show parting that can be mistaken for cleavage.
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Collecting and studying crystals with interesting habits, twinning, and epitaxy |
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markbeckett
Joined: 06 Oct 2016
Posts: 41
Location: Cornwall
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| Posted: Nov 25, 2016 14:00 Post subject: Re: Please help identify this mineral/crystal. |
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| Sphalerite I think - Does the matrix hold any grey/black fine-grained meta-sedimentary rock? |
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James Catmur
Site Admin
Joined: 14 Sep 2006
Posts: 1467
Location: Cambridge
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| Posted: Nov 25, 2016 16:19 Post subject: Re: Please help identify this mineral/crystal. |
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| Me too |
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