Mizainite is a metallic ore.
By 2323, the Bajorans had started to supply the Cardassians with mizainite mined from Bajor's moons. (ST - Terok Nor novel: Day of the Vipers)
In 2369, Rom told Quark that he had heard from Krax that Stakoron II in the Gamma Quadrant had rich deposits of mizainite. (DS9 episode: "The Nagus")
According to Lauren, Holna IV had enough mizainite deposits to keep the Dominion's shipyards running for years during the Dominion War. (DS9 episode: "Statistical Probabilities")