My 10th grade math teacher was pretty much identical to this. I've never seen someone get so genuinely excited about presenting math theory year after year. I also had a college constitutional law prof who got so worked up talking about the majesty of the constitution... and it was completley genuine. There are a ton of really amazing teachers and professors in The Teaching Company's collection of subjects... worth checking out.
I don't think I will ever forget that water frozen in nature is a mineral for the rest of my life. I think he's great! ------------ I never had this teacher, but we had a history teacher at a private school who would bring historic weapons to class and once drove it through the wall or something. He was legendary until a couple students ended the fun for the rest of us. I suppose he may have come off as slightly unstable to them--but everybody else loved him. Why the property damage incident wasn't the end of our fun, I don't know.