Titanium dioxide has many uses and is relied on widely for its non-toxic, non-reactive and luminous properties. It is not only used to whiten foods, cosmetics and paints but can help drive discovery. It is used to detect gold, uncover the impact of meteorites and expose forged artworks.
Deciphering Earth's secrets with rutile
Rutile forms under high pressure and temperature in igneous and metamorphic rocks. In Australia we find it in mineral sand deposits associated with ancient beaches and dunes on the east, west and southern coastlines of Australia.
Our researcher Mark Pearce is using rutile to understand what minerals might have once been in a rock but have since been destroyed.
"Rutile is great for recording the history of a rock because the titanium doesn’t like to move around. It is often left behind when a lot of the other elements get sucked out as fluids move through the rocks,” Mark says.
Rutile gets us closer to gold
Separately, our researcher Adam Bath has mapped rutile to show its relationship to the broader mineral pattern of ancient gold systems.
“By mapping very small amounts of rutile forming within the surrounding rocks, we can understand some important details about the environment when the rutile crystallised.
"This includes things like how much carbon dioxide was in the mix, temperature, and pH. Potentially detecting when we are getting closer to a gold deposit," Adam says.
Using rutile to find meteorites
Both Mark and Adam are using spatial variations in the minerals that make up rock to guide them towards ore deposits. However, similar changes can help us unravel altogether more ‘impactful’ geological events.
Rutile also has some mineral cousins: brookite, anatase, and akaogitte. Akaogitte is a natural form of titanium dioxide. It has the same chemical formula as its cousins. Simultaneously, it has a different crystal structure caused by the very high pressure when it formed. This pressure can only happen deep inside the earth’s mantle or during meteorite impacts.
It is one of a few useful minerals that we can use to find meteorite craters. Studying it can help us unravel the extreme conditions that rocks on Earth experience when they get hit by rocks from space.
Uncovering art forgery with rutile
Rutile's high titanium dioxide content makes it a key ingredient for processes that use titanium dioxide. This includes everyday things, like cosmetics, sunscreens and paints. But titanium dioxide is also used to spot forged artworks.
Titanium dioxide was not widely available until 1910. This means art historians and researchers can use the presence of titanium dioxide in white pigments to identify modern forgeries being sold as authentic works.
Rutile is a mineral with many roles, not just in ordinary life as an essential ingredient or guiding us to gold. Its significance extends to being a crucial part of groundbreaking scientific discoveries, enabling us to look deep into Earth's past and unravel enduring mysteries.