Dong Zhongshu
The "Chunqiu Fanlu" (14), attributed to Dong Zhongshu (179–104 BC), says "císhí" 磁石 "lodestone" attracts iron and "jǐngjīn" 頸金 "neck metal; burning-mirror" attracts fire; Joseph Needham and Wang Ling suggest the name "neck metal" derives from either the mirror being hung round the neck, or because necks are concave things.