Abstract Commonly used gold chloride and its diluted forms are compared with gold bromide for potential microcrystalloscopic differentiation of 3,4-methylenedioxyamphetamine (MDA) and related amphetamine derivatives. The crystal formation characteristics of MDA, mescaline, and 2,5-dimethoxy-4-ethylamphetamine (DOET) with diluted and undiluted gold chloride allow differentiation of these drugs,...