Duridium
Duridium was a type of ore.

In 2371, the  hauled a load of duridium ore to Solais V. The ship was due to return to Deep Space 9 the following month. ()

In 2373, a Changeling posing as Doctor  claimed to Miles O'Brien that he had ordered two sets of new duridium alloy darts that he had told him about. ()

Refined duridium was used in the construction of barrels, and was resistant to Jem'Hadar rifles. ()

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Materials
Geology