Glimspar

Glimspar is a magic-imbued mineral that is found in especially high concentrations at The Glimmering Archiourano. It is the reason why the islands float in the air, why the vegetation on them is an odd magenta color, and why the clouds swirling around them glitter in shades of orange and purple.
It has been discovered that when glimspar is put in a furnace instead of coal, it burns for many times longer and hotter, emitting an iridescent smoke. Like the islands it originates from, it can hold vessels like Airships aloft. It is highly sought after in the Eight States of Chronan that base their might and prowess on steam-based technology, but most of the mines are governed by The Dragon Lords of the Archiourano. Some Dragon Lords pay salary to their miners while others keep slaves guarded by their dragonborn and kobold underlings. A common punishment for criminals in the Eight States of Chronan is to send them to work in the glimspar mines.
Sky Pirates abuse this dependency on the substance by frequently raiding airships and glimspar mines. They have invented many ways to obscure their ships from the watchful eyes of the dragons, such as illusions and clouds of darkness.