铌铁矿 nítiěkuàng columbite Origin Definitions Defs Strokes Stroke Words Sentences Sents 铌 鈮 ní niobium niobium, a grayish-white metallic element with a high melting point and stable chemical properties, often used in making special stainless steel, high-temperature alloys, and superconductors铁矿 鐵礦 tiěkuàng iron ore ore containing iron minerals