<p>I found this beautiful euhedral pyroxene crystal in thin section today. There is one thing that I can´t explain though.</p>

<p><a href="https://i.sstatic.net/oqxaC.jpg" rel="noreferrer"><img src="https://i.sstatic.net/oqxaC.jpg" alt="enter image description here"></a></p>

<p>In crossed polarizers, the crystal shows two different interference colors, which do not change as I rotate the table (no color shifting, no extinction).</p>

<p><a href="https://i.sstatic.net/HFlka.jpg" rel="noreferrer"><img src="https://i.sstatic.net/HFlka.jpg" alt="enter image description here"></a></p>

<p>As far as I know, this happens only in basal sections. But then why are there two different interference colors ? Could it be pyroxene twinning ?</p>

<p>Thanks for all your answers.</p>

CC BY-SA 3.0
2016-12-06T20:28:37.400Z
Yes, this is a textbook example of pyroxene twinning.
Gimelist
CC BY-SA 3.0
2016-12-06T21:51:23.047Z
for what it's worth there is a slight difference in colour in plane polarized light
haresfur
<mineralogy>
Could this be pyroxene twinning ? (thin section)
Petr Hykš
# Could this be pyroxene twinning ? (thin section)

(Asked by: username_0 on 2016-12-06)

I found this beautiful euhedral pyroxene crystal in thin section today. There is one thing that I can´t explain though.

[![enter image description here](https://i.sstatic.net/oqxaC.jpg)](https://i.sstatic.net/oqxaC.jpg)

In crossed polarizers, the crystal shows two different interference colors, which do not change as I rotate the table (no color shifting, no extinction).

[![enter image description here](https://i.sstatic.net/HFlka.jpg)](https://i.sstatic.net/HFlka.jpg)

As far as I know, this happens only in basal sections. But then why are there two different interference colors ? Could it be pyroxene twinning ?

Thanks for all your answers.

**Tags:** mineralogy

> **Comments:**
> **username_1**: Yes, this is a textbook example of pyroxene twinning.  
> **username_2**: for what it's worth there is a slight difference in colour in plane polarized light  

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## 0 answers

