magnesian.

Etymology: < post-classical Latin magnesia (from 13th cent. in British sources), name of several amalgams and alchemical substances, usually non-ferrous (e.g. magnesia opalina , a red sulphide of antimony) < Hellenistic Greek or Byzantine Greek μαγνησία , name of several ores and metallic amalgams in alchemical writers from the 2nd cent. onwards < ancient Greek Μαγνῆτις λίθος ‘the Magnesian stone’, a name of lodestone (see magnes n.) and of a mineral, probably a kind of talc, described by Theophrastus as resembling silver.Sense 2 probably arose from the early confusion of certain manganese ores with lodestone; post-classical Latin magnesia is used in this sense by Albertus Magnus (a1250), as is Middle French, French magnesie in the mid 16th cent. Compare the statement of Pliny ( Nat. Hist. 36. 66) that lodestone (magnes lapis ) was used in making glass, and compare also manganese n. 1a, especially quots. 1677, 1672, and 1755. Post-classical Latin magnesia alba (see Compounds) probably arose from use contrastively with magnesia nigra black magnesia (see sense 2); N.E.D. suggests also s.v. the possibility of influence by earlier magnes carneus flesh-magnet, applied c1550 by J. Cardan ( De Subtilitate vii, Opera III. 475) to a white earth resembling osteocolla, because it was found to adhere strongly to the lips, and was therefore supposed to have the same attraction for flesh that the lodestone has for iron.