Cortenum
Cortenum is an element that was used in the manufacture of verterium cortenide, an alloy utilized by the Federation in the construction of the inner layer of the warp coils found in  engine nacelles. 

In 2372, B'Elanna Torres was fairly certain  could purchase needed monocrystal cortenum and polysilicate verterium at Hemikek IV. ()

While at the salvage yard on Hunhau in 3189, Michael Burnham claimed that  had told her to obtain warp coils to melt down for cortenum. This was a ruse to allow her to speak privately with Cleveland Booker. ()

de: Monokristallines Cortenum
Elements