Even a completely useless piece of rock is already a piece of rock in space. It can be used for shielding, counterweight for a spinning habitat, melted into sim

Even a completely useless piece of rock is already a piece of rock in space. It can be used for shielding, counterweight for a spinning habitat, melted into simple shapes to support your habitats, etc.. You can even use it for propulsion - fling it away with a mass driver or vaporize with an arc-jet through a thruster nozzle!