For fabric content I use the match test. I just cut a small piece of fabric and light it with a match. You don't really need to burn it completely, a edge is enough. When it is cool feel the edge, if it feels stiff and scratchy it is some kind of synthetic if not it's a natural fiber.
To deal with the raveled edges I would just trim and sew either a straight or zigzag stitch a 1/4 from the edge.
Congradulations on your find!