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Macromolecular Crystallography Helps Determine the Atomic Structure of New Volcanic Mineral

Date: 
Thursday, July 6, 2017
Contact: 

Communications Advisor: Nick Sharp-Paul 
Phone: +61 3 8540 4178 | Mobile: +61 411 098 838 | Email: media@synchrotron.org.au

A Monash-led group of geoscientists used the macromolecular crystallography beamline (MX2) Australian Synchrotron to help them determine the atomic structure of a new mineral discovered in a volcanic area of Far Eastern Russia. 

The research, which was published in American Mineralogist by Prof Joel Brugger of Monash and collaborators from Australia and Russia may provide insight into the processes responsible for the geochemical evolution of Earth. 

The authors reported that an analysis of Nataliyamalikite was challenging because of the small size of single crystals, composite nature of larger aggregates and the extreme light sensitivity of the mineral and the surrounding sulfur matrix. 

Nataliyamalikite grains could not be isolated using optical microscopy. 

X-ray powder diffraction measurements on microcrystals of Nataliyamalikite at 100 K indicated that  the structure was orthorhombic. 

The mineral which has only two atoms, thallium and iodide, in the asymmetrical unit cell, is considered to be a distorted version of rock salt.

The beam diameter was reduced to 7.5 nanometres by a collimator at the Australian Synchrotron MX2 micro-focus beamline to match the crystal size of the micro-aggregates of Nataliyamalikite, which were extracted from the amorphous sulfur matrix by focused ion beam scanning electron microscopy.

MX2 beamline scientist Dr Jason Price assisted in processing the beamline data, which was compared with a synthetic equivalent. 

Electron backscatter diffraction at Monash and in Russia confirmed an orthorhombic crystal lattice of the mineral at ambient conditions. 

The thallium-rich Nataliyamalikite forms in high temperature fumaroles, (thermal openings in areas surrounding a volcano) as a component of arsenic and sulfur-rich coating on lava and scoria around the vents.

In the paper, the authors also provided a description of the process that give rise to concentrations of thallium, leading to the formation of Nataliyamalikite.

Read more on the Monash website. 

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