Diamonds and Rust?

The rocks in Monument Valley, on the Utah/Arizona border, appear red due to the presence of iron oxides. It is now appears, contrary to earlier assumptions, that 'rust' can be stable almost 3000 km below the Earth's surface on its iron core (https://www.theguardian.com/science/2022/may/25/terrawatch-earth-core-rusty-atmosphere). It has also been suggested that heaps of rust, from the Earth's core, might have 'hitched a lift' back to the surface via mantle plumes. This might have accounted for the fact that the planet's atmosphere suddendly became oxygen-rich some 2.5 bn years ago. Without atmospheric oxygen, life as we know it, would be impossible.