Ferrous niobium fluoride

Ferrous Niobium Fluoride, 2NbF5.3FeF2.4HF.19H20 or NbaFe3F16. 4HF.19H20, is obtained in greenish-yellow, thin prisms by dissolving iron and niobic acid in equivalent proportions in hydrofluoric acid. 

Iron Tantalates.—The meta-salt, Fe0.Ta206, has been obtained more or less pure by fusing tantalum pentoxide and ferrous fluoride with excess of potassium chloride.8 Iron tantalates occur naturally in niobites and tantaMtes. The ore tapiolite has the approximate composition FeO.Ta2Os the tantalum may be partially substituted by niobium.9... 

Interference by ferrous salts can be prevented by adding 1,10-phenanthroline as masking agent. Uranyl and thorium salts can be masked with fluorides, niobium with hydrogen peroxide and other ions by EDTA. 

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