What element has the symbol 'Gd'?

The story behind the answer

‘Gd’ is the symbol for gadolinium, a lanthanide (rare-earth) metal with atomic number 64. It’s named after Finnish chemist Johan Gadolin. Gadolinium is strongly paramagnetic, which makes it useful in MRI contrast agents, and it also has a high neutron absorption cross-section, so it’s used in nuclear reactor control and shielding. It’s added to alloys to improve high-temperature performance.

To avoid mix-ups with other “G” elements: Gold is Au (from its Latin name aurum), Gallium is Ga, and Germanium is Ge. Memory tip: “Gado-” goes with “Gd”—think “Gadolin’s element: Gd.”