Well, im not a professional guitar tech, but I hold a 1st class degree in Product Design, and worked as an industrial designer before I started my PhD. I am also experienced in modifying guitars. I don't know what material the nut is. I know it isn't TUSQ, and its not the same cheap plastic you find on low-mid (and some high) guitars. The plastic feels kind of sticky, not because anything has been spilt on it, but because it is very soft and 'sticky'. Maybe this is a good thing?
Here is a video I made about Graphtech TUSQ on an acoustic, to experiment and see what difference it made over the cheap as hell plastic it came with.
http://www.youtube.com/watch?v=pccGikT2cvE