One of my college buddies loaned this to me this morning and I've already finished it.
It's very good. I love the pet cat thing called a "peeve". Very cute.
A peeve finds unicorn bones and gives them to a 16 year old girl who pieces them back together. Then, by accident her mother, a sorceress, brings the black unicorn back to life.
Amazing book well worth the effort to find it, followed by Red Unicorn and Silver Unicorn. Library loan here I come....