When I was a teenager in the 80’s I read a book called “Elizabeth”. The book was about a teenage girl who either had magical powers or magic was somehow insinuated. The cover was black and I believe it had a broken mirror on the cover. In the story she had a red mark on her upper thigh that she received from a spider bite maybe but it was identical to another character in the book, like an aunt or something. She would remark in the book how older men were attracted to her and she enjoyed it. I have looked everywhere online for the book and even called my local library. I guarantee the book is not about Queen Elizabeth or Elizabeth Taylor because that is all that I find out there. Please help!!
Got to be Elizabeth, by Jessica Hamilton. Check the Goodreads page, which shows the cover where she’s looking in a mirror.
Oh, some editions use Hamilton’s pseudonym, Ken Greenhall.
I can’t remember the whole plot, but there is an aunt and a magical element of time travel mirror Take a look at ELIZABETH ELIZABETH by Eileen Dunlop, also published under the title of ROBINSHEUGH. I saw 4 or 5 different covers.