I did just fine on that mineralogy midterm. In fact, with the extra-credit points I racked up in the beginning of the semester, I got over 100% on the exam. So, I spent a week and a half being a miserable jerk for no good reason.
I think that I studied too hard for the exam, which barely scratched the surface of the details in our textbook. In class, we just sorta skimmed over ideas - not going into detail - but our reading was pretty in-depth. Having no idea what to expect or, better yet, what was expected of me, I just studied everything in a ton of detail.
The exam was very long - but it required very broad answers. I spent too much time answering the first 10 questions (in as much detail as I thought was expected) and then panicked when I realized that I still had half an exam to complete within 10 minutes. So, I rushed through the last half of the exam, spending very little time and attention on the details. I did just as fine on those questions as I did on the first few.
Lesson: For the final, I should really try to give broader, less specific answers. I could study less, too, but what would be the point of that?