In the earliest episodes of the original Star Trek, the Enterprise's warp drives are powered by and/or regulated by "lithium", and a maintenance visit is made to the "lithium cracking station" of Delta Vega.

Memory Alpha observes,

According to Star Trek Encyclopedia, originally, lithium was said to be used to control the warp reaction, but it was quickly realized that since lithium was a real element, with known properties, it would not be able to do some of the things the writers wanted it to do.

In the prequel series Enterprise, no mention is made of lithium per se as a substance relevant to warp travel, and ships are apparently already using dilithium (e.g. the ENT episode Affliction explicitly mentions dilithium).

In current Star Trek canon, was crystalline, metallic, or elemental lithium (atomic number three on the periodic table) ever actually used in warp engines? I can see two ways to interpret the use of the term "lithium" in the context of the entire franchise:

  • There is a period of time when Earth and/or Federation ships switch from dilithium to lithium and then later back to dilithium again. This could be a temporary measure due to a dilithium shortage, environmental legislation, etc., with lithium used briefly as a stopgap during the period when dilithium is unavailable. This could also represent a failed experiment, with lithium being introduced as a newfangled replacement for aging dilithium tech, only for lithium to be proven too expensive, too dangerous, etc. for continued use, with a project to retrofit lithium-powered Constitution class ships back to the "old" dilithium tech starting up in the mid-Kirk era.
  • Earth/Federation ships (at least from the time of the NX-01) have always used dilithium, but some people in the early Kirk era call it "lithium" as a sort of nickname or shorthand, similar to the way many Earth humans today use the term "gas" to refer to a variety of hydrocarbon-based fuels whose exact nature depends on the context of conversation.

I know the out-of-universe reason that "lithium" was dropped from the script. The question is solely about whether this represents an in-universe change in technology (i.e. a brief period of time in which actual lithium is used) or whether the "change" has been retconned as a terminology issue or similar.

In response to an answer by M. A. Golding, it does make sense that the terms "lithium" and "dilithium" are both shortened forms of some longish chemical name. What I'm looking for is actual evidence of this. For example, if there is an early script-writer's guide that says, "The power matrix of the Enterprise's engines is regulated by crystals of Tessellated di-Lithium Hydro-argentate, or "lithium" as it is called by the crew.", that would be an excellent answer. If there is an episode where some established characters continue to use the term "lithium" while new characters (e.g. a crystal merchant du jour) call it "dilithium" (e.g. "I understand that you need some high-quality level five dilithium hydrate for your engines, eh.?"), that would also be an answer.

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    or maybe you get dilithium from cracking lithium into two parts? ;)
    – NKCampbell
    Oct 16, 2020 at 16:51
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    Actually lithium in gas phase consists of Li2 molecules i.e. dilithium molecules. So, this idea with adding "di" wasn't particularly smart.
    – Mithoron
    Oct 16, 2020 at 18:36
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    Enterprise had a lot of faux archaic terms to make it seem like a prequel but never actual early tos ones like timewarp factor or vulcanian. Oct 16, 2020 at 19:47
  • Or, alternatively, there is no way to twist this into a single "canon".
    – Spencer
    Mar 5, 2022 at 14:49

2 Answers 2


The Star Trek: The Next Generation Technical Manual gives a long-form name for dilithium crystals as "2<5>6dilithium 2<:>1 diallosilicate 1:9:1 heptoferranide":

Star Trek: The Next Generation Technical Manual excerpt, quoted below


The key element in the efficient use of M/A reactions is the dilithium crystal. This is the only material known to Federation science to be nonreactive with antimatter when subjected to a high-frequency electromagnetic (EM) field in the megawatt range, rendering it "porous" to antihydrogen. Dilithium permits the antihydrogen to pass directly through its crystalline structure without actually touching it, owing to the field dynamo effect created in the added iron atoms. The longer form of the crystal name is the forced-matrix formula 2<5>6dilithium 2<:>1 diallosilicate 1:9:1 heptoferranide.

I don't know if you'd count this as part of current canon; the next page goes on to say that by the TNG era they can synthesise dilithium, which contradicts DIS:

Star Trek: The Next Generation Technical Manual excerpt, quoted below

highly complex atomic structure is based on simpler forms discovered in naturally occurring geological layers of certain planetary systems. It was for many years deemed irreproducible by known or predicted vapor-deposition methods, until breakthroughs in nuclear epitaxy and antieutectics allowed the formation of pure, synthesized dilithium for starship and conventional powerplant use, through theta-matrix compositing techniques utlizing gamma radiation bombardment.


It has always been my assumption that dilithium has a long and complex chemical name, and that a phraase like dilithium oxide or dilithium hydride is part of that chemical name, perhaps at the front, the back, or somewhere in the middle.

And I assumed that in the era of early TOS the official starfleet jargon for that substance was shortened to "lithium", but someone complained that could cause confusion with the element lithium, and so someone in Starfleet Command decreed that the substance would not be known by its full chemical name, nor as lithium, but as dilithium instead.

And if dilithium was mentioned in the era of Enterprise as a substance vitally necessary for warp drive, then dilithium should have been the officially approved phrase to use instead of the long and complex chemical name, until it was changed by being shortened to lithium at an unknown date and then restored to the longer dilithium early in the era of TOS.

And I sort of suspect that calling the warp drive crystals lithium, the same name as a common element, caused some sort of disaster when negotiating with aliens for dilithium crystals. Starfleet thought it would get vitally needed dilithium crystals but actually received relatively useless lithium instead, perhaps leading to many bloody defeats in a war for lack of enough dilithium!

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    Do you have any support for this in terms of actual in-universe or "word of god" or even contemporary writings?
    – Zeiss Ikon
    Oct 16, 2020 at 18:40
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    imagine if were Discovered that 700 years in the future, there isn't even any dilithium. Talk about bloody wars...
    – NKCampbell
    Oct 16, 2020 at 18:50
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    While my preference is to evaluate the original series by only what the audience at the time would have thought and they would have agreed lithium was possibly used or shorthand. I believe that TNG and voyager have implied that the periodic table has a hundred more elements than currently known. I'd assume Dilithium is one of those exotic elements with some similar electron configuration to lithium. Further its been established in tech manuals as I recall that enough of the structure of Dilithium is in subspace that it doesn't get annihilated by the antimatter stream. Oct 16, 2020 at 19:39
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    @NKCampbell I see what you did there. Oct 17, 2020 at 9:57
  • @NKCampbell indeed. If such were Discovered, one would wonder why someone doesn't just up and say, "Hey, we can use lithium instead! I think I have a copy of the specs for a Lithium-Version Constitution class warp core somewhere down here...". That would make me suspect that atomic number 3-lithium is not actually a real option for warp drives (that is, it doesn't just go a little slower, require more maintenance, or need semi-regular visits to Delta Vega for restocking, it doesn't really exist at all). Oct 19, 2020 at 10:51

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