The addendum to my Friday post… here are the videos that I mentioned.
They’re not as nice quality as I’d like (and I’m not sure where the purple tint comes from), but they’re decent enough. I wish I had thought to turn the stage more slowly while I was doing these though, particularly for this above video. You can see how the grains flash, but there are a lot of feldspar grains in that view that you can’t really see the extinction come and go because I’m moving too fast. I apologize.
Here is the large microcline under the thin section.
It definitely illustrates the idea behind extinctions much more clearly than my prior text or pictures. It’s a pretty neat deal.