Handheld device of human design which can detect the presence of the mineral naquadah. Later models were based on the scanner taken to Abydos by the first team to go through the Stargate. But the technology was eventually modified to detect the mineral in its multiple forms.
The Earth ship Prometheus also possesses powerful sensors capable of detecting naquadah at or near the surface of a planet from orbit.
"Stargate" the Movie - Lieutenant Brown uses an analysis device to discern the ore the Abydonians are mining is the same as the material of the Stargate.
Ex Deus Machina - A bomb squad uses naquadah detectors to try and locate deposits of the mineral inside the Halcyon tower, but they are dumbfounded until Carter realizes the naquadah makes up the building's infrastructure itself.