Glittergun
From Tardis Wiki, the free Doctor Who reference
The Glittergun was a weapon developed by the enemies of the Cyberman during the Cyber-Wars once their vulnerability to gold had been discovered by The Human Race and other allies of The Vogans.
The weapon fired gold dust particles or even sometimes molten gold into the chest units of the Cyberman plugging up their respiration system and suffocating them. (DW: Revenge of the Cybermen)