In which episodes of Star Trek: TOS were Dilithium Crystals shown on screen? This is not counting episodes where they were just mentioned; only episodes where they were actually shown.


3 Answers 3


I thought about it some more, and there were three episodes. I checked my DVDs, and hunted up all the scenes I could find.

  1. Mudd's Women Season 1

Spock shows one of the crystals that was damaged in rescuing Mudd.

Spock's hand holding a Dilithium crystal

  1. The Alternative Factor Season1

Lazarus and crazy Lazarus both steal crystals from the Enterprise. You see the crystals several times, and also the dilithium chamber.

Here's the dilithium chamber:

Uhura standing next to a Dilithium chamber

Crazy Lazarus with two crystals in a bag. Lazarus with two crystals in a bag.

Crazy Lazarus with the crystals in his UFO:

Kirk throwing crazy Lazarus through his UFO into the corridor between the universes (crystals visible):

Lazarus (not the crazy one) with the crystals in the alternate universe:

crystals visible in the craft

  1. Elaan of Troyius Season 3

    This is the one everybody remembers, probably because Elaan was wearing them as a necklace - and she spent most of the episode wearing costumes that would make a stripper blush. I can't believe it took me nearly 40 years to recognize the ham-fisted play on words "Helen of Troy" and "Elaan of Troyius"

Burned out crystal in the dilithium chamber - note that it is now in a the engine room proper - and that the crystal looks like the ones in "The Alternative Factor."

Elaan with the necklace (no one knows that it is of dilithium yet):

Kirk standing next to Elaan, who is wearing a necklace with crystals

Elaan has left the bridge and come back. Spock discovers her necklace is made of dilithium.

Spock approaching Elaan

Spock and Scotty installing the "crude crystals" in the dilithium chamber. If you look, you'll see the burned out one lying there. It looks like the ones from "The Alternative Factor" but it is burned looking.

Elaan leaving the Enterprise. Notice she's wearing her necklace again. Kirk must have given it back.

It seems the props folks didn't have a real clear idea of what the dilithium crystals should be and what they should look like.

  • After seeing all three, I suspect that the Dilithum Crystals in the necklace from "Elaan of Troyius" are the ones I bought fragments of from Chris Doohan. It's been a long day, but I will post photos tomorrow. Thanks to all, for your expertise in Star Trek TOS. (Funny I was never a big fan of TOS, but Love "ST Enterprise" and "ST Voyager". Stan
    – Stan
    Feb 5, 2016 at 8:48
  • Maybe I'm not remembering correctly, but in Mudd's Women weren't they referred to as "Lithium" crystals?
    – Xantec
    Feb 5, 2016 at 21:10
  • #1. that Spock is holding, appears to be a healthy Quartz Crystal with some Iridescent Hematite on it's base and part of one facet.
    – Stan
    Feb 5, 2016 at 22:30

In TOS 'Elaan of Troyius', we see Dilithium Crystals twice. We see some in a necklace:

and also see some burnt out in the assembly itself:

metal rack with burnt out crystals visible inside


Besides the three episodes that were previously mentioned, I believe there is a brief scene in The Paradise Syndrome. I've only seen it once, as it seems to have been deleted from most syndication packages, but it's when Enterprise is closing in on the asteroid. Scotty does a quick visual inspection of the crystals where he reports to Spock, "Dilithium crystal circuit's failing, sir."

Found a still:

Scotty looking at an open rack with Dilithium crystals

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