I have zero interest in rocks. None. Unless it is one on my finger, and even then I don't really care that much about carrots or cut. Whoever wrote my degree plans, however, thought I should take a few geology classes in both undergrad and grad school. For multiple semesters in college I sat through lectures on rocks, the age of the Earth, talked about fossils and what really killed off the dinosaurs. I stayed awake. But. Just barely. I also remember in labs, having to classify types of rocks. chert, sandstone, obsidian. A few were pretty...but most were just brown stones to me. One of the ways we had to identify them was based on the Mohs scale of hardness. You would scratch the surface of one rock or mineral on another to see which one was harder. The values range from 1 - 10, depending on how easily it is scratched. In the hospital they always ask you to rate your pain. On a scale of 1-10. And those scales and numbers and ways of classifying things are...