Gravium is a very rare mineral and has the property of emitting negative energy as soon as it is irradiated with neutrons, making the Interstellar Drive possible.
Xerium 42 is the primary energy source of your Space ship, the Weapons and the shields.
Newtonium is very useful to create Antigravitation and therefore has been named after the great physicist Sir Isaac Newton (1642-1726), who formulated the laws of motion and universal gravitation (and the one who came up with the name "Newtonium" was probably was a little joker).
The interstellar drive is a masterpiece of science. For centuries it was thought that nothing can move faster than light.
The Impulse drive is the method of propulsion that your ship uses when you are travelling below the speed of light.