I have been observing a nepheline specimen under polarized light and found some interesting places. I have taken several images. The first shows a micro-geode with parallel polarizers, second with crossed polarizers. I wonder.. could these crystals inside be nepheline ? If not, what mineral could it be ? The thin section was labelled "nepheline". Also.. is the bubble real air bubble or anything else ?
Parallel polarizers: https://www.flickr.com/photos/violetplanet/30883853122/in/album-72157671897003403/
I have also observed pyroxene crystals in Fe-solution (in parallel nicols could be mistaken with biotite), olivine and there should be nepheline. I have also found secondary quartz filling a cavity near olivine crystals. I believe the original rock was some kind of basalt.
Thanks for help.