Cerulium

Cerulium was a mineral found on Ceres. It had the property of inhibiting free will. The native Cerulians used it as the basis of their civilisation until they were destroyed by an asteroid. Chunks of cerulium remained in space. Some fell to Earth and was recovered by the Department. Inspector Drake planned to use cerulium to control the people of London. He introduced cerulium bracelets to the students of Magdalene Academy, and developed an experimental cerulium-powered weapon called the Inhibitor. However, the Inhibitor exploded when it was tested, and K9 destroyed the bracelets. (K9TV: Sirens of Ceres)