Ghost impurity

In the sci-fi story, "8113", a ghost impurity is an undetectable and unorthodox chemical signature found in the ore of a geotomaton. As a result, that person is undetectable to the multi-spectral scanners that otherwise can geolocate individuals anywhere in the Universe. Ghost impurities are often embedded into spies or covert operatives, sometimes without their knowledge if they are a sleeper agent. The procedure to replace one's typical ore impurity with a ghost impurity is considered highly dangerous and experimental, since there are only a few compatible chemical compounds per each individual person (often only one). The procedure is often akin to torture and was banned as a medical or military procedure during the Talking War.

A ghost impurity may be one part-per-million difference to their typical ore chemical formula. This atomic-level tweak is sometimes enough to steal another's identity entirely, or become completely unseen by government detectors throughout the Spectraverse.

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