Selenite (Satin Spar) Tower 10cm

Selenite, or Satin Spar, is a variety of gypsum that forms long single planed crystals. Commonly mined in Morocco, it is often used in industry for fertilizers and construction. 
When polished, Satin Spar displays a fairly unique ability called chatoyance. Chatoyance is essentially the light flash observed when the crystal is moved.
Each tower is approx 10cm high