Tin can crumble in a cold winter

Below about 13 °C, white tin is metastable and can transform into grey tin, a brittle form that makes an object crumble.

Ordinary tin, the white metal, is stable above 13.2 °C. Below that, the thermodynamically preferred phase is grey tin, which has a diamond structure and is brittle. The change wants a seed — a speck of grey tin, or a long time in serious cold — and then it spreads. Organ pipes in cold churches and tin buttons in old collections have been found eaten by it.

The rate at temperatures just below the threshold is extremely slow. Alloys used in modern solder are much less willing. A winter windowsill will not powder a tin cup over a season. A museum sample, seeded and stored cold for years, might. The allotropic fact is solid. The folklore that Napoleon's army lost its buttons to tin pest, and therefore the Russian campaign, is not. The buttons were not shown to be pure tin, and the campaign had larger problems.