Magnesium Niobates

Hexagonal tablets and prisms of 4MgO.Nb₂O₅ (density 4.43) are obtained by adding magnesium chloride to potassium niobate solution, fusing the precipitate with anhydrous magnesium chloride, and lixiviating with water and hydrochloric acid. If the precipitated salt is fused with borax and lixiviated, MgO.Nb₂O₅ is obtained in small prismatic crystals. Joly's 3MgO.Nb₂O₅ could not be confirmed.

White, flocculent MgO.Nb₂O₅.7H₂O precipitates from mixed solutions of magnesium chloride and sodium niobate.