
Rutile is a common accessory mineral in high-temperature and high-pressure metamorphic rocks and in igneous rocks.
Characteristics[]
Rutile is the preferred polymorph of titanium dioxide in such environments, because it has the lowest molecular volume of the three polymorphs; it is thus the primary titanium-bearing phase in most high-pressure metamorphic rocks, chiefly eclogites. Within the igneous environment, rutile is a common accessory mineral in plutonic igneous rocks, although it is also found occasionally in extrusive igneous rocks, particularly those that have deep mantle sources, which are found in the igneous environment particularly as products of autogenic alteration during the cooling of plutonic rocks.