|a black, yellowish, or reddish-brown mineral, found in igneous rocks, metamorphosed limestones, and quartz veins. It is a source of titanium. Composition: titanium dioxide. Formula: TiO2. Crystal structure: tetragonal|
|[C19: via French from German Rutil, from Latin rutilus red, glowing]|
|rutile (r'tēl', -tīl') Pronunciation Key
A lustrous red, reddish-brown, or black tetragonal mineral that is an ore of titanium. Rutile usually occurs as prismatic crystals in other minerals, especially as dark needlelike crystals in quartz. Chemical formula: TiO2.