Take it to a fabric store...someone there will probably know what it is.
a picture would help, but you can take it to JoAnn's or any other fabric store and they could probably tell you.
I have a small sample of fabric and I am in desperate need of more, but I have no idea what kind it is! I have searched all online and did my own at-home tests on it and I am not getting clear results. Is there a place I can mail the fabric to and they will do tests on it and tell me the results?