Rutile is a purple stone found in small clusters within metamorphic stones, as well as within granite. Like pitchblende, it is magma-safe.
 In real life
Rutile is one of three mineral forms of titanium dioxide (the others being Anatase and Brookite). Rutile has one of the highest refraction indices of all natural material. It is used for the manufacture of refractory ceramic,a white pigment, or a production of titanium metal.
another titanium ore, same comment applies