That geode is so beautiful! I've been fascinated with stones and rocks since I was a child, and I suspect that science still has a lot to discover about them. I have a large amethyst, and I'm certain that strange things happen when I'm close to it!
I've got into the habit of collecting a small stone or two each time I climb a mountain, which is very often, so my collection is growing alarmingly!
I'd love to know if there's any way to tell whether a rock contains a geode.