Gadolinite

Gadolinite is a mineral that contains rare earth elements. Originally called ytterbite, it was later named after Johan Gadolin, who discovered the chemical element yttrium in this mineral. It does not contain much of the element gadolinium, which was separately named after Gadolin. The mineral is divided into gadolinite-(Y) and gadolinite-(Ce) based on whether it has more yttrium or cerium.

Besides yttrium, the elements erbium and terbium were also first discovered through analysis of gadolinite.