I believe the release date of this book is at least 5 years after TNG ended. There are a a few old technical manuals from TOS which precede my own birth by many years, perhaps you are referring to these. Anyway, here is one of many amazing paragraphs from this book, reminding one of just how close the star trek writers (with help from their science advisors) got it.
'Finally, the Star Trek writers added one more crucial component to the matter-antimatter drive. I refer to the
famous dilithium crystals (coincidentally invented by the Star Trek writers long before the Fer-milab engineers
decided upon a lithium target in their Antiproton Source). It would be unthinkable not to mention them, since they
are a centerpiece of the warp drive and as such figure prominently in the economics of the Federation and in
various plot developments. (For example, without the economic importance of dilithium, the Enterprise would
never have been sent to the Halkan system to secure its mining rights, and we would never have been treated to
the "mirror universe," in which the Federation is an evil empire!)
What do these remarkable figments of the Star Trek writers' imaginations do? These crystals (known also by their
longer formula— 2<5>6 dilithium 2<:>1 diallosilicate 1:9:1 heptoferranide) can regulate the matter-antimatter
annihilation rate, because they are claimed to be the only form of matter known which is "porous" to antimatter.
I liberally interpret this as follows: Crystals are atoms regularly arrayed in a lattice; I assume therefore that the
antihydrogen atoms are threaded through the lattices of the dilithium crystals and therefore remain a fixed
distance both from atoms of normal matter and one another. In this way, dilithium could regulate the antimatter
density, and thus the matter-antimatter reaction rate.
The reason I am bothering to invent this hypothetical explanation of the utility of a hypothetical material is that
once again, I claim, the Star Trek writers were ahead of their time. A similar argument, at least in spirit, was
proposed many years after Star Trek introduced dilithium-mediated matter-antimatter annihilation, in order to
justify an equally exotic process: cold fusion. During the cold-fusion heyday, which lasted about 6 months, it was
claimed that by putting various elements together chemically one could somehow induce the nuclei of the atoms
to react much more quickly than they might otherwise and thus produce the same fusion reactions at room
temperature that the Sun requires great densities and temperatures in excess of a million degrees to generate.
One of the many implausibilities of the cold-fusion arguments which made physicists suspicious is that chemical
reactions and atomic binding take place on scales of the order of the atomic size, which is a factor of 10,000
larger than the size of the nuclei of atoms. It is difficult to believe that reactions taking place on scales so much
larger than nuclear dimensions could affect nuclear reaction rates. Nevertheless, until it was realized that the
announced results were irreproducible by other groups, a great many people spent a great deal of time trying to
figure out how such a miracle might be possible.
Since the Star Trek writers, unlike the cold-fusion advocates, never claimed to be writing anything other than
science fiction, I suppose we should be willing to give them a little extra slack. After all, dilithium-mediated
reactions merely aid what is undoubtedly the most com-pellingly realistic aspect of starship technology: the
matter-antimatter drives. And I might add that crystals—tungsten in this case, not dilithium—are indeed used to
moderate, or slow down, beams of anti-electrons (positrons) in modern-day experiments; here the antielec-trons
scatter off the electric field in the crystal and lose energy.
There is no way in the universe to get more bang for your buck than to take a particle and annihilate it with its
antiparticle to produce pure radiation energy. It is the ultimate rocket-propulsion technology, and will surely be
used if ever we carry rockets to their logical extremes. The fact that it may take quite a few bucks to do it is a
problem the twenty-third-century politicians can worry about.'-Lawrence M. Krauss, The physics of Star Trek