DiscoverySunmetal was discovered by Shejlt-Rajh forces when an asteroid full of it landed in the Greater Amujnalden Region during the Sazashi Revolution. The then Grandmaster of Light, through Divination, noticed that energy and gravity warped oddly around the metal in the crater. He realized that, with proper configuration and electric charge, the metal generated anti-gravitational properties.
UseSunmetal became an arm of the Sazashi offense (and later the Valuser'ran military). At first they made crude vessels, essentially floating islands, but as the technology was further studied and refined they went on to make airships and other aircraft.
Resource WarSunmetal has been the lynchpin of many resource wars. Less so in modern times, when people know how to make Sunmetal on their own, but the original Sunmetal amount was highly sought after. (Outlined in The Rings of Jhoutai.)
Modern DayNow that sunmetal is understood, it is produced easily enough using noble metals. It is used in 25: Meissner Antigravity to generate the field, and is most commonly produced by the ValuSelu Pact and Federation of Free Planets
Uses of SunmetalSunmetal is the basis of anti-gravitational technology, which has seen many uses throughout history. It is used in Valuser'ran airships, which were naval vessels outfitted with Sunmetal plating to make them flight capable.
Meissner Antigravity is a pivotal technology used to negate or generate the force of gravity. It does this by running a current through a lasagna of crystalline and metallic materials that generate a psuedo-gravitational force.