First, although the most famous use of trilithium was in Soran's torpedo, the use of trilithium as a weapon of mass destruction dates back to the earliest reference I'm aware of to the substance, "Starship Mine" in TNG. A small quantity is considered highly destructive, and is a natural byproduct of the Enterprise's warp engines.
It is volatile, but stable enough to be stored short-term without decaying into other substances or exploding without severe provocation. Then we have ST:Generations. From the Generations script:
Riker is unfamiliar with trilithium. We are given an order of magnitude of destruction for trilithium explosives, which naturally does not match the effect of the Generations torpedo. It is referred to as unstable. More about this in a minute.WORF
One of the dead Romulans had a
tricorder. We analyzed its sensor
logs and found they were scanning
for signature particles of a
compound called trilithium.
RIKER
Trilithium?
WORF
An experimental compound the
Romulans have been working on. In
theory, a trilithium-based
explosive would be thousands of
times more powerful than an
anti-matter weapon. But they never
found a way to stabilize it.
"Image in the Sand" tells us that Romulan plasma torpedoes commonly contain a certain amount of trilithium. This tells us one of two things is true:
- Between Generations and DS9: "Image in the Sand" - four years - trilithium has gone from being experimental to being a staple of the Romulan arsenal. This would help explain how Romulan torpedoes do so much damage in "The Die is Cast."
- Romulans have, since TOS: "Balance of Terror" and the introduction of plasma torpedoes, been using trilithium-based weaponry. This would explain the exceptional yield of the plasma torpedoes in "Balance of Terror." However, they had not tapped its full potential, only using it in small amounts in a volatile (plasma, rather than stable solid) form.
"For the Uniform" tells us something very important. Two hundred kilograms of trilithium resin will render a planet uninhabitable for fifty years. Even if only a few grams to a few kilograms of trilithium can render a planet uninhabitable - closer to the quantity seen in "Starship Mine," which is in a fairly small container - the half-life of trilithium is best measured in years. That tells us how unstable it is.
"By Inferno's Light" shows the Dominion trying to pull a Soran. Soran's anti-star weapon may have been experimental four years earlier, but is clearly replicable.
"The Chute" in Voyager reiterates that trilithium is a waste product of the warp engines, and reinforces the way it can be easily developed into a potent weapon in the hands of terrorists. Between "The Chute" and "Starship Mine," I think it's clear that unscrupulous individuals don't need a galaxy-class physicist to do damage with trilithium.
"Course: Oblivion" gives us a weird outlier reference. They refer to trilithium ore in a throwaway line. Of course, if dilithium is naturally occurring, perhaps occasionally trilithium is found with it, but if trilithium is highly unstable, this should be unusual.
So we actually know a bit about trilithium. The least consistent datum is the throwaway line in "Course: Oblivion."
