Energized Malachite

A potent magical material needed to construct and maintain Spelljamming helms, among other purposes. It's raw form is unstable and explosive, making it difficult to mine or transport. It reacts violently with magic until it can be refined. After refining, it becomes a magical conductor, allowing it to change the local laws of reality.
Malachite is only found on life-bearing worlds, which is something of a tragedy. The precise effects of mining it are unpredictable, but it is always destructive to the environment. The governments of most worlds are not willing to allow mining on their planets in the modern age.
The transportation of malachite is highly risky endeavor. It is costly to move due to the safeguards that must be observed to prevent it from exploding. Also, it's extremely valuable, always tempting theft. Pirates targeting this commodity must also be equipped to handle this quirk, as well at the possibility of a Bleak-Scuttle.
Malachite defines Spelljamming. A Spelljamming helm cannot be constructed without it. Further, while a Spelljammer's carrying capacity (by weight) is set the by the amount of malachite in the helm, the maximum size of the ship (i.e. volume) is determined by the largest single stone used in its creation. Thus, while you can add additional stones to carry more mass, the highest quality gem you are able to obtain determines the overall size of the vessel.

Type

Ore/Mineral