Duranium

Duranium is an extremely strong metallic element used in alloys for hull construction of the ships and stations of numerous races, including the Federation, Andorians, Klingons and Cardassians during the 23rd and 24th Centuries. During the Dominion War, the Gallamites were supplying duranium to the Federation for the war effort.

Krieger waves can put a hole in solid duranium, something that is rather hard to accomplish. (TNG: "A Matter of Perspective")

The skulls of Soong-type androids are partly composed of duranium. (TNG: "The Chase")

"Captive Pursuit" established that the access tunnels found on Deep Space Nine are composed of duranium and are impervious to sensors.

Duranium-235 is used in phaser arrays.

According to the DS9 TM, Duranium is a naturally occuring ore in planetary crusts such as the crust of Bajor. This would suggest that duranium itself is not an alloy, but rather that there is a family of alloys where duranium is the largest component. This is further supported by the use of the term "duranium-235," which implies that duranium is in fact an element, one that has an isotope with an atomic weight of 235.

References

• TOS: "The Menagerie, Part I"
• TNG: "A Matter of Perspective"
• DS9:
  • "Emissary"
  • "Captive Pursuit"
  • "Q-Less"
  • "Dramatis Personae"
  • "The Siege"
  • "The Way of the Warrior"
  • "Ferengi Love Songs"
  • "Penumbra"
• VOY:
  • "Threshold"
  • "Initiations"
  • "Alice"