From Lexicanum

The term Archeotech is generally given to ancient finds of technical artefacts in the hives. The richest source of archeotech is usually derelict domes, but various old machines can be found at the bottom of any deep layer of hive debris. The value of archeotech can be varied by what it is. For example, isotropic crystal fuel rods can be traded for a good amount of price, while old rusted machinery can only be sold for the value of metal it contains.

Source

• Specialist Games Necromunda Resources - p.69