It is that time for teaching optical fibers again. We have a few demonstrations and I have been really pleased to find a great supplier of highly polished selenite.
Selenite and ulexite (caveman TV rock) both have striations running parallel to each other throughout the crystal. These column TIR the light up from the bottom to the top of the crystal.
Here is my selenite cube in action.
Selenite is also great if you make a big spectrum in your classroom. You can capture the spectrum in space as it travels to your screen.
I was so keen to show this selenite I used the link that I had purchased from. Great news in that Ian has now sorted through his pieces and has made a listing for the highly polished ends we desire. Here is the new link