Gallium is a metal that melts in the warmth of your hand
A silvery metal solid at room temperature, gallium melts in your hand at body heat — and its melting point helps define the global temperature scale.
Most metals shrug off any heat a human body can offer. Gallium does not. The element is a brittle, silvery solid on a cool benchtop, but its melting point sits at just 29.76 °C (302.91 K) — below normal body temperature. Cup a piece in your palm and within minutes it slumps into a shimmering puddle.
That low, sharply defined transition makes gallium more than a party trick. Because pure gallium always melts at exactly the same temperature, NIST and other metrology labs use it as a defining fixed point of the International Temperature Scale of 1990 (ITS-90), calibrating precision thermometers against it.
The same melt-and-resolidify cycle that ruins it as cutlery makes it a flexible tool: gallium can be poured, frozen into a mould, and melted again without harm. It is one of only a handful of metals — alongside mercury, caesium and rubidium — that liquefy anywhere near room temperature.
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