text: Although cyanide is cheap, effective, and biodegradable, its high toxicity has incentivized to alternative methods for extracting gold. Other extractants have been examined including thiosulfate (SO), thiourea (SC(NH)), iodine/iodide, ammonia, liquid mercury, and alpha-cyclodextrin. Challenges include reagent cost and the efficiency of gold recovery. Thiourea has been implemented commercially for ores containing stibnite. Yet another alternative to cyanidation is the family of glycine-based lixiviants.