Star Fuel

Countless thousands of years of technological progress, and we're back to firing our ships with glorified lumps of coal.

— Hans Beckett, stoker

Not to be confused with Rocket Fuel
Star Fuel, also known as Star Coal, is a dark purple synthetic material used to power the emerging Vortex Drives. Its adoption has led to the re-invention of specialised fuel bunkers aboard spacefaring vessels, though it can also be transported in the same cargo holds used for other bulk loose materials such as metal ore or grain. The process of manufacture is still poorly understood, and thus several different grades of quality grades exist.

Grades

The lowest grade of Star Fuel is a laminate material with a greasy pearlescent sheen, comprised of thin, flaky layers that resembles shale. It is the least space, weight, and power efficient grade of Star Fuel, but it is also the cheapest on the fledgling market and the easiest and quickest to manufacture.
Middling grades of Star Fuel form solid, irregular lumps with various properties that vary on the quality of manufacture. Colour varies between pale purple intermixed with brown impurities at the lower grades, and a deep, almost black purple flecked with white specks at the higher grades. The weight density of the material remains mostly consistent across all grades, with the biggest difference between grades being the power density. Price and availability of these grades is primarily based on location, as most manufactories are set up to only produce one consistent grade at a time.
The highest grade of Star Fuel has undergone a phase transition, forming hard crystals a vibrant purple in colour and with a waxy sheen. This grade boasts the best space, weight, and power efficiency ratings, but it is also by far the most time consuming and painstaking to manufacture, and therefore commands a steep premium. It is difficult to find this grade in large quantities on the civilian markets, as the vast majority of production is reserved for local military fleets.

Star Dust

All grades of Star Fuel, with the exception of the crystalline grade, has the habit of generating tiny flakes and fine dust when lumps rub against each other. This "Star Dust" feels greasy to the touch when dry, forms a sticky tar when wet, and has a habit of settling on every available surface when it gets airborne. This makes it extremely hazardous when inhaled, as human lungs generally don't do well when they are clogged up with tar.