Note:  Do not rely on this information. It is very old.


Rutile is a crystalline form of titanium dioxide (TiO2), a substance remarkable for being trimorphous, ie. crystallising in three distinct forms-viz. rutile, anatase, and brookite. Of these forms rutile is the commonest, and exists as brown lustrous crysta1s of the Quadratic system possessing a specific gravity of 4.2. It frequently occurs in igneous rocks, e.g. granite, and also in hard limestones, [ANATASE; BROOKITE, TITANIUM.]