The Maltasion asteroid belt was an asteroid belt in the Gamelan system. It was positioned between the Gamelan sun and Gamelan V.

On stardate 44307, the USS Enterprise-D was forced to tow an unmanned garbage scow, which was threatening the population of Gamelan V, through the Maltasion asteroid belt so that it could be directed into the sun where it would be safely destroyed. (TNG: "Final Mission")

"mal-TAY-zhun" was the pronunciation for Maltasion from the script pronunciation guide. [1]
There is a discrepancy in the spelling of this belt's name in the script. In the pronunciation guide, it was spelled Maltasion, whereas, in the script's text, it was spelled Meltasion. The Star Trek Encyclopedia (4th ed., vol. 2, p. 34) and favored the latter.