Elements 57 through 71 plus the elements scandium (21), yttrium (39), and thorium (90) are all called rare earth elements.
When many of these elements were discovered, the process of extracting them was difficult and costly. Scientists also believed they weren’t largely available in Earth’s crust.
This is how they came to be called “rare.”
In actuality, most are fairly abundant, and with extraction so much easier these days, the only thing rare about them is their designation.
