Gems.

The planet of Gurkland is known to be a planet covered much by water, but the land is rocky, full of caverns with many precious gems in bright colors and magical abilities. In this world the gems, because of their widespread diffusion have very low prices, and magicians build rings, bracelets, necklaces that increase the physical and mental capacity of an individual. (Apparently, the vast presence of precious stones is because of the vanity of our Goddess.)
Much of the futuristic buildings, houses and spaceships are made of material extracted from these gems ,which the magical material of the gems offers special protective characteristics for the land as zero impact to the environment, without the use of harmful and polluting materials such as oil to the asphalt road which is practiced today in the streets of humanity, and the ability to withstand any type of degradation without the need for road maintenance.