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Protactinium

Radioactive protactinium is found in uranium ores. It is a relatively rare, naturally-occurring element and is costly to produce. Below 1.4 K, this element has exceptional superconducting properties.

Protactinium is a lustrous, silvery element. In fact, its brightness is reflected in its name derived from the Greek "protos aktino" – meaning "first ray." Despite being attacked by oxygen in the atmosphere, protactinium retains its metallic luster for a long time.

One of protactinium's isotopes, protactinium-231, vigorously emits alpha particles – fast-moving helium-like particles – making it a hazardous toxic material. In fact, protactinium's usefulness is limited due mainly to its radioactivity, its rarity and high cost.