The World Around Us

Polonium radiohalos in Shap granite.

Photo-micrograph of a biotite flake from the Shap Granite (Lake District, England) showing a polonium-218 radiohalo with a faint outer ring and an enlarged polonium-210 radiohalo. The additional ring is caused by the different energy of the alpha particles of the plutonium isotopes.

Credit: Dr Andrew Snelling