From: KnifeCenter.com

by Hoot , Diversityville, Liberal-sota, Friday, March 13, 2015, 14:50 (3483 days ago) @ StoneWolf

G-10
a fiberglass based laminate. Layers of fiberglass cloth are soaked in resin and are compressed and baked. The resulting material is very hard, lightweight, and strong. Surface texture is added in the form of checkering. G-10 is an ideal material for tactical folders because of its ruggedness and lightweight. It is usually available in black.

http://www.knifecenter.com/info/knife-handle-materials

My take is it's basically of the genus micarta.