Andalusite
The Andalusite was studied for the first time by Werner, from specimens from Spain. Both this mineralogist and Delamétherie believed that the specimens came from Andalusia, so the latter gave the mineral the name it now bears. However, it seems that the specimens they studied came from El Cardoso (Guadalajara), a town that they assumed was located in Andalusia.
It is a polymorph with two other gemstones: Kyanite and Sillimanite. Polymorphous means that they share the same chemical composition and ingredients but have a different crystal structure.
Most andalusite tends to be a greenish-brown color, but can also have flashes of orange, pink, or red when turned from one angle to another.
This color change is known as pleochroism and must be taken into account when cutting it.