Clear-blue Andara

This Andara is smaller. At first glance it looks plain, at least compared to its bluegreen cousin. But what's remarkable is how it changes color depending upon the light and its surroundings. 

All photos: CC BY-NC 4.0

Sometimes this triangular crystal appears colorless. Other times it appears to be violet, grey, or light blue. At times it completely absorbs the color of an adjacent crystal, or it takes on color from somewhere else--I'm not sure where!