Sorry for the slow response, I've been in China most of the summer. Unfortunately, I don't know why it deforms into distinctive subgrains like that. If someone has an explanation, I'd be glad to hear it.
My understanding is that, over a particular temperature range, quartz deforms by starting to break into a set of subgrains. I don't remember the technical term, but I'll call each of them a "domain". Each domain is at a slightly different orientation from its neighbors, so it goes extinct at a slightly different angle when you rotate the stage. The mismatch in orientation changes systematically across the original quartz grain. So, as you rotate the stage, you're seeing the successive extinction of each domain sweep across the original large crystal. Two neighboring domains are not very different, so they go extinct at almost the same angle, but two domains at the ends of the crystal may have quite different orientations.
Great video Matt. Thanks for sharing.
Really helpful, thanks!
Thanks for sharing! This is so helpful.
thanks for sharing this, if possible please create some videos' on igneous and metamorphic texture
Yes, others have asked about metamorphic textures. I'll see what I can do. Thanks!
Why does the quartz can break into sub-grains?
Sorry for the slow response, I've been in China most of the summer. Unfortunately, I don't know why it deforms into distinctive subgrains like that. If someone has an explanation, I'd be glad to hear it.
Why does quartz exhibit undulose extinction?
My understanding is that, over a particular temperature range, quartz deforms by starting to break into a set of subgrains. I don't remember the technical term, but I'll call each of them a "domain". Each domain is at a slightly different orientation from its neighbors, so it goes extinct at a slightly different angle when you rotate the stage. The mismatch in orientation changes systematically across the original quartz grain. So, as you rotate the stage, you're seeing the successive extinction of each domain sweep across the original large crystal. Two neighboring domains are not very different, so they go extinct at almost the same angle, but two domains at the ends of the crystal may have quite different orientations.
Very good
thank youuuu
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