This item is a tourmaline slice from Snellius Minerals LLC designed to showcase the strong pleochroism of tourmaline.  The pleochroism is so strong that a polariscope is not necessary, however additional experiments can be done with the tourmaline slice if a bright enough polariscope is available.  The first photo shows the slice backlit by a cell phone flashlight when viewed along the plane of the a-crystallographic axes.  The second photo shows the tourmaline slice backlit by a cell phone flashlight when viewed along the c-crystallographic axis.  The video shows the transition back and forth between the first and second photos; the pleochroism of this tourmaline is absurd!   The third, fourth, and fifth photos are taken under normal lighting conditions with a ruler to provide an idea of the shape and size of this particular slice.  If you want to learn more and see a demonstration of a tourmaline slice in action check out the video "Snellius Minerals LLC Tourmaline Slice" on Youtube. 

https://youtu.be/Fk15-KkWx5Y

Each of these slices is unique, as they are cut from natural crystals.  These were made as cheaply as possible; in order to do this the windows perpendicular to the c-crystallographic axis were cut and polished only to 220 grit.  These windows were then coated with clear nail polish, thereby saving a huge amount of time and effort compared to the multiple polishing steps the other tourmaline slices went through.  These specimens also are a bit more included than other more expensive tourmaline slices.  However, all have been tested and should be able to demonstrate the experiments shown in the Youtube video.  Thank you, and check out some of our other items for sale.  We aim to provide the nerdiest mineral samples possible!  Combined shipping available for many items.