name of movie

hi everyone.........I know I'm posting this in the wrong area but I'm new and totally confused.  I just have a question.  about 40 years ago when I was little I watched a old movie about an alien princess landing on earth she was radio active  and everyone she touched she killed because of it.  at the end a group of people who had a cabin in the woods throw some kind of acid on her that killed her.  The locket she wore contained a message from her father as a peaceful greeting to the people of earth. This was in black and white does anyone know the name of the movie.  again sorry about the post but it's been driving me nuts for years and I can't find a link to it anywhere because I don't know the name.  Thanks again for any help.

chuck the ducky