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Wapień cieszy&am
Joined: 28 Jul 2025
Posts: 7
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 Posted: Jul 28, 2025 07:47 Post subject: Identification of 2 minerals under microscope |
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Dear Colleagues,
I have a request for you regarding the identification of two minerals I observed under a microscope.
The first one has no cleavage and is in high relief. The second one sometimes occurs within it, and then you can observe cracks extending from its surface. These occur surrounded by biotite and amphibole.
I thought it might be zircon, but some of the specimens appear to be twinned.
I should add that it is gneiss.
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James Catmur
Site Admin
Joined: 14 Sep 2006
Posts: 1482
Location: Cambridge
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| Posted: Jul 28, 2025 08:28 Post subject: Re: Identification of 2 minerals under microscope |
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| Welcome to FMF
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Wapień cieszy&am
Joined: 28 Jul 2025
Posts: 7
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| Posted: Jul 28, 2025 08:34 Post subject: Re: Identification of 2 minerals under microscope |
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Thanks :) Hello! :) | James Catmur wrote: | | Welcome to FMF |
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Jordi Fabre
Overall coordinator of the Forum
Joined: 07 Aug 2006
Posts: 5088
Location: Barcelona
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| Posted: Jul 28, 2025 08:50 Post subject: Re: Identification of 2 minerals under microscope |
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| Wapień cieszy&am wrote: | Thanks :) Hello! :) | James Catmur wrote: | | Welcome to FMF |
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Hi Wapień,
It looks like our HTML doesn’t handle the Polish alphabet properly and breaks your username into:
Wapień cieszy&am
Would you like me to change it to:
Wapien cieszy
so it doesn’t look so odd?
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Wapień cieszy&am
Joined: 28 Jul 2025
Posts: 7
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| Posted: Jul 28, 2025 09:11 Post subject: Re: Identification of 2 minerals under microscope |
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You are right with this :) But maybe wait one day and I send you pm with my name and change to it.
Regards
Andrzej
| Jordi Fabre wrote: | | Wapień cieszy&am wrote: | Thanks :) Hello! :) | James Catmur wrote: | | Welcome to FMF |
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Hi Wapień,
It looks like our HTML doesn’t handle the Polish alphabet properly and breaks your username into:
Wapień cieszy&am
Would you like me to change it to:
Wapien cieszy
so it doesn’t look so odd? |
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Roger Warin
Joined: 23 Jan 2013
Posts: 1246
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| Posted: Jul 28, 2025 09:31 Post subject: Re: Identification of 2 minerals under microscope |
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Hello,
Did you cut these thin sections yourself?
I think the thickness exceeds 30 µm.
For the first two photos, I would have thought of pyroxenes, twinned.
A crystal is sectioned along the base and contains an inclusion that is typical of an exsolution. This base appears to be close to 124° and 56°, so it is an amphibole.
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Wapień cieszy&am
Joined: 28 Jul 2025
Posts: 7
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| Posted: Jul 28, 2025 09:46 Post subject: Re: Identification of 2 minerals under microscope |
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No, they were cut in a laboratory specializing in sample preparation for microscopic examination. Therefore, their thickness should be less than 30 micrometers.
I assumed they weren't pyroxenes because they were euhedral, while other components, such as amphiboles (photo 7), were not.
So what could these minerals in photo 8 be (blue arrows), and what could be inside them?
| Roger Warin wrote: | Hello,
Did you cut these thin sections yourself?
I think the thickness exceeds 30 µm.
For the first two photos, I would have thought of pyroxenes, twinned.
A crystal is sectioned along the base and contains an inclusion that is typical of an exsolution. This base appears to be close to 124° and 56°, so it is an amphibole. |
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Bob Carnein
Joined: 22 Aug 2013
Posts: 359
Location: Florissant, CO
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| Posted: Jul 28, 2025 11:31 Post subject: Re: Identification of 2 minerals under microscope |
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| It looks to me like zircon. The high relief and pleochroic halos are typical.
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Wapień cieszy&am
Joined: 28 Jul 2025
Posts: 7
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| Posted: Jul 28, 2025 11:39 Post subject: Re: Identification of 2 minerals under microscope |
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I mean what is inside the zircon in photo 5 and 6.
| Bob Carnein wrote: | | It looks to me like zircon. The high relief and pleochroic halos are typical. |
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Bob Carnein
Joined: 22 Aug 2013
Posts: 359
Location: Florissant, CO
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| Posted: Jul 28, 2025 11:58 Post subject: Re: Identification of 2 minerals under microscope |
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| If you are referring to what's inside the diamond--shaped, cracked crystals, I think that is zircon. Considering that this is a gneiss, the diamond-shaped crytals might be sillimanite.
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Wapień cieszy&am
Joined: 28 Jul 2025
Posts: 7
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| Posted: Jul 28, 2025 12:04 Post subject: Re: Identification of 2 minerals under microscope |
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| OK, now I got it. Thanks for explanation this :)
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Bob Carnein
Joined: 22 Aug 2013
Posts: 359
Location: Florissant, CO
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| Posted: Jul 28, 2025 12:57 Post subject: Re: Identification of 2 minerals under microscope |
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| Sphene is another possibility for the diamond-shaped crystals.
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Wapień cieszy&am
Joined: 28 Jul 2025
Posts: 7
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| Posted: Jul 28, 2025 13:19 Post subject: Re: Identification of 2 minerals under microscope |
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I think it is no sphene, because this mineral (blue arrows) also occurs in this sample and it looks different.
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Bob Carnein
Joined: 22 Aug 2013
Posts: 359
Location: Florissant, CO
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| Posted: Jul 28, 2025 15:33 Post subject: Re: Identification of 2 minerals under microscope |
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| I agree.
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