Bismuth is one of the most strongly diamagnetic materials; it's metallic but fairly brittle and a solid at standard conditions (but melts at 271°C). The metallic element is grey in colour but the iridescence on the surface of the sample shown above is due to a thin layer of bismuth oxide on the surface. Bismuth is said to be the heaviest element with a stable nucleus. Its most stable cation Bi3+ has an interesting electronic configuration which makes it useful in functional materials.
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