Transparisteel was a hardy and transparent material that was primarily used to make windows and other parts of starfighters, such as cockpit canopies. A major component of transparisteel was lommite ore. Transparisteel windows could be created in a way that made them blaster-proof, as is with the Galactic Empire's TIE/ln space superiority starfighter, but not lightsaber-proof.
The eye sockets of Darth Vader's helmet were made of transparisteel.