The third stage in the second series of Phase Transitions. The lattice of the crystals is changing and this puts them under mechanical stress. As a result, they adapt their shape by twinning (a zigzagging of the crystal lattice), resulting in striped patterns. I find this image visually very fascinating.
There is an intermediate stage (see below) but here something went wrong with the scanning of the slide. There is obviously some file corruption here in the lower stripe of the image. I will have this slid rescanned and will then repost the image. Maybe one bit was flipped. If a cosmic ray or a fault on the hard disk or whatever caused this, I don’t know. However, visually, it is an interesting picture, not least because of the mistake. In this picture, the stripes of the twinning are just beginning to appear.
Pictures: Svend Keller