Tuesday, 7 December 2010

Mapping Apollo 17 lunar regolith



In 1972 Apollo 17 landed on the moon in the Taurus-Littrow Valley on the eastern rim of Mare Serenitatis. Astronauts Gene Cernan and Harrison Schmitt discovered and sampled unusually coloured soil in the form of glass spheres. These spheres occur in a range of colours, from orange to black and green, and in sizes from ten's to hundred's of micron.

Scientists hypothesize that the spheres are the result of fire fountain eruptions that occurred during the same time period as the bulk of mare basalt extrusion, and that they owe their unique colours to a combination of specific chemical compositions, quench crystallization, and devitrification processes.

Automated mineral analysis has allowed the quantification of mineral and glass components, as well as the textural attributes of glass spheres, on a particle-by-particle basis. Researchers can now directly compare samples collected at various locations and draw conclusions on the geological process responsible for the formation of these unique lunar environments.

References:

QEMSCAN mineral map of pisoliths

QEMSCAN cross-sectional images of Pisoliths

The distinctive sub-rounded particles in this image are known as pisoliths, which form at the Earth’s surface as a result of weathering of a rock, typically basalt igneous rock. 
No two pisoliths are the same – although they generally have a nucleus and core which is then surrounded by several concentric layers.


Pisoliths can form a bauxite ore, the main source of aluminium.  
Extraction of aluminium from the ore involves a complex chemical digestion technique known as the Bayer Process. The efficiency of this process s is significantly reduced if impurities other than aluminium hydroxide (green) are present in the ore, such as quartz (pink), clays (brown) and iron oxides (orange) in the image.

FEI’s Automated Mineralogy solutions are helping mining companies better understanding ore variability in terms of mineralogy and textures. QEMSCAN mineral maps as the one above provided by courtesy of BHP Billiton lead to improved metallurgical processing.