Leucoxene, fine-grained anatase formed by natural alteration of ilmenite, is yet another ore. Star sapphires and rubies get their asterism from oriented inclusions of rutile needles.

[24][25] Titanium dioxide (B) is found as a mineral in magmatic rocks and hydrothermal veins, as well as weathering rims on perovskite.

[31] In chloride process, the ore is treated with chlorine and carbon to give titanium tetrachloride, a volatile liquid that is further purified by distillation.

Titanium dioxide crystal size is ideally around 220 nm (measured by electron microscope) to optimize the maximum reflection of visible light.

[37] The occurrence of abnormal grain growth brings about a deviation of a small number of crystallites from the mean crystal size and modifies the physical behaviour of TiO2.

As little as a few parts per million (ppm) of certain metals (Cr, V, Cu, Fe, Nb) can disturb the crystal lattice so much that the effect can be detected in quality control.

[38][full citation needed] Approximately 4.6 million tons of pigmentary TiO2 are used annually worldwide, and this number is expected to increase as use continues to rise.

[citation needed] Some grades of modified titanium based pigments as used in sparkly paints, plastics, finishes and cosmetics – these are man-made pigments whose particles have two or more layers of various oxides – often titanium dioxide, iron oxide or alumina – in order to have glittering, iridescent and or pearlescent effects similar to crushed mica or guanine-based products.

[46] Titanium dioxide and zinc oxide are generally considered to be less harmful to coral reefs than sunscreens that include chemicals such as oxybenzone, octocrylene and octinoxate.

The EU Scientific Committee on Consumer Safety considered nano sized titanium dioxide to be safe for skin applications, in concentrations of up to 25 percent based on animal testing.

[50] The rutile form is generally used in cosmetic and sunscreen products due to it not possessing any observed ability to damage the skin under normal conditions[51] and having a higher UV absorption.

[52] In 2016 Scientific Committee on Consumer Safety (SCCS) tests concluded that the use of nano titanium dioxide (95–100% rutile, ≦5% anatase) as a UV filter can be considered to not pose any risk of adverse effects in humans post-application on healthy skin,[53] except in the case the application method would lead to substantial risk of inhalation (ie; powder or spray formulations).

[54] Coating TiO2 with alumina, silica, zircon or various polymers can minimize avobenzone degradation[55] and enhance UV absorption by adding an additional light diffraction mechanism.

Titanium dioxide is produced in varying particle sizes which are both oil and water dispersible, and in certain grades for the cosmetic industry.

The exterior of the Saturn V rocket was painted with titanium dioxide; this later allowed astronomers to determine that J002E3 was likely the S-IVB stage from Apollo 12 and not an asteroid.

The chloride process is only mentioned in 8% of patent families, although it provides 60% of the worldwide industrial production of titanium dioxide.

[60] Nanosized titanium dioxide, particularly in the anatase form, exhibits photocatalytic activity under ultraviolet (UV) irradiation.

Hence, in addition to its use as a pigment, titanium dioxide can be added to paints, cements, windows, tiles, or other products for its sterilizing, deodorizing, and anti-fouling properties, and is used as a hydrolysis catalyst.

[66] In thin film and nanoparticle form, titanium dioxide has the potential for use in energy production: As a photocatalyst, it can break water into hydrogen and oxygen.

[68] Further efficiency and durability has been obtained by introducing disorder to the lattice structure of the surface layer of titanium dioxide nanocrystals, permitting infrared absorption.

[70][71] In 1995 Fujishima and his group discovered the superhydrophilicity phenomenon for titanium dioxide coated glass exposed to sun light.

Nanosized TiO2 incorporated into outdoor building materials, such as paving stones in noxer blocks[72] or paints, could reduce concentrations of airborne pollutants such as volatile organic compounds and nitrogen oxides.

[citation needed] TiO2 whitener in food was banned in France from 2020, due to uncertainty about safe quantities for human consumption.

EFSA concluded that genotoxicity—which could lead to carcinogenic effects—could not be ruled out, and that a "safe level for daily intake of the food additive could not be established".

[87] Health Canada similarly reviewed the available evidence in 2022 and decided not to change their position on titanium dioxide as a food additive.

[88] The European Union removed the authorization to use titanium dioxide (E 171) in foods, effective 7 February 2022, with a six months grace period.

It may be used to increase whiteness and opacity in dairy products (some cheeses, ice cream, and yogurt), candies, frostings, fillings, and many other foods.

[94] In 2023, the Consumer Healthcare Products Association, a manufacturer's trade group, defended the substance as safe at certain limits while allowing that additional studies could provide further insight, saying an immediate ban would be a "knee-jerk" reaction.

[98] Andrew Maynard, director of Risk Science Center at the University of Michigan, rejected the supposed danger from use of titanium dioxide in food.

[103] In the environment, titanium dioxide nanoparticles have low to negligible solubility and have been shown to be stable once particle aggregates are formed in soil and water surroundings.