Lanthanum is used to make specialty optical glass.
Tips
memory
Like most metal element names, this is a phono-semantic compound: the 钅 (jīn) radical signals 'metal', and the right side 阑 (lán) gives the sound. Same pattern as 铜 (tóng, copper), 铁 (tiě, iron), 锌 (xīn, zinc).
culture
镧 gives its name to the 镧系元素 (lánxì yuánsù) — the lanthanide series, the 15 metallic elements 57–71 critical to magnets, lasers, and electronics. China holds the world's largest reserves and dominates global supply.
