Our Heroine will be finding a book that a mage (approximate equivalent social level to a scholar or a parish priest, I'd think) was using as a diary/journal/workbook. Obviously, it's not going to be a neat, professionally bound thing with nicely squared off edges and such, but--what *would* it likely be? Parchment, paper, papyrus, or something else? Would it have a cover, and if so, of what? Would it be crudely hand-stitched, or held together some other way? Would there be unused blank pages in the back, or would he tend to add them as he needed them? Would it be written on in ink, or in charcoal/lead/something else?
And, what kind of condition would it probably be in a century after it was originally written in?
If it matters... it was probably intended to last at least a decade or so (for his own reference, and for his apprentice to use), and the area in which the story is set has a lot of grazing animals.