Etymology: In early use < (i) Middle French siderite (French sidérite , †syderite ) lodestone (1430), and its etymon (ii) classical Latin sidērītēs (masculine), sidērītis (feminine), name of various minerals, including the lodestone and a kind of diamond (all in Pliny) < Hellenistic Greek σιδηρῖτις lodestone, kind of precious stone, use as noun of feminine of ancient Greek σιδηρίτης of or relating to iron < σίδηρος iron (see sidero- comb. form¹) + -ίτης -ite suffix¹. In later use (iii) directly < ancient Greek σίδηρος + -ite suffix¹. Compare earlier siderites n.In sense 3 after post-classical Latin siderum (T. Bergman, 1782 or earlier), a name given to this chemical under the impression that it was a new metal: compare earlier post-classical Latin hydrosiderum , German Wassereisen , lit. ‘water iron’, denoting the same substance (both J. K. F. Meyer (1780)). In senses 4 and 6 after German Siderit a blue variety of quartz (von Moll, 1799 or earlier), native ferrous carbonate ( W. K. von Haidinger Handbuch der bestimmenden Mineralogie (1845) 499), after French sidérose siderose n.). In sense 7 probably as a shortening of aerosiderite n.; compare siderolite n.²

Etymology: < classical Latin sidērītis, a name given to various plants with curative properties (Pliny; < Hellenistic Greek σιδηρῖτις < ancient Greek σίδηρος iron (see sidero- comb. form¹) + -ῖτις -ite suffix¹), perhaps in allusion to the use of these plants to treat wounds made by iron weapons (compare ironwort n.).