Talking Physics

 

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.

What I am really excited about is finding a supplier of very highly polished long pieces of selenite.
https://www.ebay.co.uk/itm/223448782835

What you must do first is contact Ian and he will check if the piece has the properties we want.
Here is the piece Ian found for me.

I am so impressed with it. It was used with all our physics classes today.

That looks great David, thank you for sharing. I will definitely contact that seller and try to get one.

Those are very impressive size pieces

 

Your link is to the wrong one apparently David, but I just bought the one that is most appropriate.

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

https://www.ebay.co.uk/itm/223448782835

I have changed the one above. Always a good idea to message Ian and say you want an optical grade selenite slice.

Selenite has a hardness of 2 on Mohs scale. I have tried putting sticky back plastic on one end of this piece of selenite.

Very pleased with my bit. I think it was ulexite you sent me a few years ago, that was a much smaller piece but is that rather better, or would they be the same if the same length?

I am also pleased with my bar, which arrived swiftly in the post. Shining a laser through it is good as it hardly disperses at all  🙂  Thank you for sharing.

[Author]

Posts