Bomb materials, trace of an accelerant?

Ducky found traces of a strange material on our second victim, and you're not going to believe what it is.

Controlling mercury releases through end-of-pipe techniques, such as exhaust gas filtering, may be especially appropriate to processes using raw materials with trace mercury contamination - fossil-fuelled power plants, cement production, the extraction and processing of primary raw materials such as zinc, gold and other metals, and the processing of secondary raw materials such as steel scrap.