Diagram of a molecule of this compound (bottom).
Mooride polyronite B was a slow burning explosive compound. This explosive was used for controlled pressure wave ignition of small scale fusion devices. Until exposed to and activated by an energetic gamma pulse emitted by a laser detonator, this compound was stored as an inert liquid form. In 2367, this explosive was stored on aboard the Federation starship USS Enterprise-D.
In that year, mooride polyronite B was on a list of explosives that Lieutenant Commander Data and Counselor Deanna Troi searched through in an attempt to find one that could produce enough energy to release the USS Enterprise-D and an alien ship from the Tyken's Rift. (TNG: "Night Terrors")
For the remastered episode, the name was changed from mooride polyronite 4 to mooride polyronite B.
This one in particular appears to be a reference to writer Ronald D. Moore and visual effects coordinator Ronald B. Moore, with "poly-ron" referring to "more than one Ron."