Berlin, Germany / berlin090-126-325L.JPG

Berlin, Germany/berlin090

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Here is a sample of columbite (iron niobate-tantalate -- Fe(Nb,Ta)₂O₆) collected by Gustav Rose and analyzed by his brother Heinrich Rose. Because of the lanthanide contraction {LINKED: hafnium in Copenhagen Denmark} niobium and tantalum have similar atomic radii and almost always exist simultaneously in minerals. Rose called the mineral "mengite," now an archaic name. The source was the Ilmengebirge (Ilmen mountains) near Miass (old name Miask, written thusly in Rose's label), 200 km south of Ekaterinburg.