This textbook had an unusual inception. I had just started writing another one, on isotopes in the natural sciences, and was discussing it with a colleague, who surprised me and startled me. He commented that, in substance, a book about isotopes is all very nice, but that I should write a general introductory geochemistry book. I was taken aback: there are plenty of these out there already! From Brownlow [1] to Albarede [2], Misra [3], and White [4], to name just a few, there are several excellent general introductory geochemistry textbooks available, widely used by university students around the world. And once we include more specialized books, for instance about isotopes or geochronology, then we can fill not only shelves, but whole library sections with them! And really, I pointed out to my colleague that they are mostly very good, thorough, and complete textbooks, so the topic is well covered.