Magnasite is a liquid that can be used to dissolve solid objects such as locking mechanisms.
In 2363, Kira Nerys used magnasite on a duranium lock on the entrance to a Cardassian sensor tower in Serpent's Ridge. (ST - Terok Nor novel: Dawn of the Eagles)
In 2370, Quark and Rom used magnasite to gain entrance to the old chemist shop on Deep Space 9's Promenade. (DS9 episode: "Necessary Evil")