Durilliam was a poisonous gas, deadly to several species, notably Arcona, Delphidians, Gabdorins, Gamorreans, Ishi Tibs, and Twi'leks. Durilliam gases could escape from the core of wrecked starship under specific conditions.
In the year 3 ABY, Fuel Station Visavi, orbiting the moon Toshara in the Outer Rim Territories, received two durilliam shipments.