Silver Chloride
Silver chloride is a chemical compound with the chemical formula AgCl. This white crystalline solid is well known for its low solubility in water (this behavior being reminiscent of the chlorides of Tl+ and Pb2+). Upon illumination or heating, silver chloride converts to silver (and chlorine), which is signaled by grey to black or purplish coloration to some samples. AgCl occurs naturally as a mineral chlorargyrite.
Person 1: "Isn't Silver Chloride the stuff u put in the pool?"
Person 2: "No u dumbass it is chlorine."
Person 2: "No u dumbass it is chlorine."