Dreman dilithium was a specific variety of dilithium found only on planet Drema IV. Dreman dilithium was able to produce approximately three times the focal energies of the standard dilithium crystals used in the Federation, and had a recrystallization rate of double the norm. (SCE eBook: Progress)
The energy-focusing properties of Dreman dilithium threatened to destroy the planet in 2365; disaster was averted when Captain Jean-Luc Picard of the USS Enterprise-D used class-1 probes to shatter the dilithium lattices below the planet's crust. (TNG episode: "Pen Pals")
The Dremans offered their dilithium resources to the Federation when they applied for protectorate status. Ambassador Lanara Diol cautioned the Federation Council against the appearance of greed, and suggested an economic partnership with the Dremans in mining this dilithium.
Dr. Leah Brahms of the Theoretical Propulsion Group, after studying Dreman lithium, reported that adjustments to standard warp drive technology would be needed to utilize this new strain of dilithium. (SCE eBook: Progress)