News: News, NSW, Research, WA

Heaven on Earth

Dozens of rare minerals, some entirely new, others only previously reported in meteorites, have now been discovered on Earth.

The AMMRF (now Microscopy Australia) at the University of Western Australia (UWA) and the University of NSW (UNSW) has helped researchers from the ARC Centre of Excellence for Core to Crust Fluid Systems at Macquarie University (MU) confirm the identity of these exotic minerals. This is a collaborative research project with Israeli gemstone mining and exploration company, Shefa Yamim, lead by Prof. Bill Griffin at MU.

Prof. Griffin’s team found the rare minerals trapped inside melt pockets in aggregates of corundum (aluminium oxide) crystals ejected from Cretaceous volcanoes on Mt Carmel, North Israel. The flagship focused ion beam in the AMMRF at UNSW was used to extract ultra-thin samples of mineral from precise locations within this complex material. Then the AMMRF at UWA used transmission electron microscopy to identify the minerals by analysing their crystal structure and chemistry.

One of the minerals is tistarite (Ti2O3), previously known only as a single grain in the Allende carbonaceous chondrite meteorite. This is believed to have formed as high-temperature molten material condensed during the nebula stage of solar system evolution when oxygen availability was low. Other ‘nebular’ minerals from Mt Carmel include silicon carbide, grossite, hibonite, osbornite, gupeiite and wassonite, all typically found in carbonaceous chondrite meteorites. The research shows that similar conditions existed in the Cretaceous upper mantle beneath Mt Carmel. They also reveal mantle environments and parts of the global carbon cycle that were previously unrecognised.

Left: A high angle annular dark field scanning transmission electron micrograph of the sample. Right: An electron diffraction pattern used to identify the crystal structure of tistarite.