According to Alsia, her father conducted a mineralogical survey of the asteroid belt to discover that it was rich in minerals. She employed this con on Martus Mazur in order to steal 10,000 Isiks from him in 2370. (DS9: "Rivals")
This asteroid belt was only mentioned in dialogue.
According to the script, the pronunciation for Vlugta was "VLUG-tuh". 
Taking place in 2409, the computer game Star Trek Online places the Vlugta Asteroid Field within a few light years of Deep Space 9. In the game, it is a rich source of dilithium exploited by the Ferengi.