A sample of Niobium metal in the form of a beautiful rainbow anodized rod. The rods measure .5in long by .25in in diameter and weigh 3.3-3.4g each. Purity is 99.95%. Please note that this is for one rod only. Several are pictured to show the rainbow color effect produced by the anodizing process. If you prefer a more colorful sample of this silver-grey metal, these colorful anodized rods are the perfect choice. The colors are not produced from paint or dye but instead by the process of anodizing. This process creates an oxide layer on the surface which absorbs, refracts and reflects certain wavelengths of light producing the observed colors. The color depends on the thickness of the oxide layer.