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Gallium, germanium, indium, and iridium in lunar samples
Science (New York, N.Y.)
|January 30, 1970
Summary
Neutron activation analyses reveal distinct elemental concentrations in lunar samples. Gallium, germanium, indium, and iridium levels in lunar rocks differ significantly from terrestrial basalts and achondrites.
Area of Science:
- Geochemistry
- Planetary Science
- Cosmochemistry
Background:
- Understanding the elemental composition of lunar samples is crucial for deciphering their origin and evolution.
- Comparative analysis with terrestrial and meteoritic samples provides insights into planetary formation processes.
Purpose of the Study:
- To determine the concentrations of gallium, germanium, indium, and iridium in lunar samples.
- To compare these concentrations with those found in meteorites (calcium-rich achondrites) and terrestrial basalts.
- To identify geochemical differences between lunar, meteoritic, and terrestrial rock compositions.
Main Methods:
- Neutron activation analyses were performed on eight lunar samples.
- Comparative analyses included four calcium-rich achondrites and five terrestrial basalts.
- Bulk compositions of all sample types were considered for comparison.
Main Results:
- Lunar gallium concentrations are consistently around 5 ppm, higher than achondrites and lower than terrestrial basalts.
- Lunar germanium ranges from <=0.04 to 0.4 ppm, similar to achondrites but lower than terrestrial basalts (approx. 1.4 ppm).
- Indium concentrations in lunar samples (3-60 ppb) are lower than terrestrial basalts (80-100 ppb) but higher than achondrites (0.4-3 ppb). Lunar iridium is estimated between 0.1-10 ppb.
- Tranquillitatis samples show distinct geochemical signatures compared to calcium-rich achondrites and terrestrial basalts.
Conclusions:
- Lunar samples exhibit unique elemental profiles for gallium, germanium, indium, and iridium.
- These findings highlight significant geochemical differences between the Moon, Earth, and certain meteorites.
- The distinct composition of Tranquillitatis samples warrants further investigation into lunar geological processes.
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