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Updated: Jul 12, 2026
08:55
Methods of Ex Situ and In Situ Investigations of Structural Transformations: The Case of Crystallization of Metallic Glasses
Published on: June 7, 2018
Mossbauer effect and high-voltage electron microscopy of pyroxenes in type B samples
Science (New York, N.Y.)
|January 30, 1970
Summary
Lunar clinopyroxenes show ordered distribution of iron, magnesium, and calcium. This cation distribution suggests equilibrium at temperatures below 680°C, with implications for crystal structure.
Area of Science:
- Geochemistry
- Mineral Physics
- Materials Science
Background:
- Lunar clinopyroxenes are key minerals for understanding the Moon's geological history.
- Cation distribution in pyroxenes influences their physical and chemical properties.
- Previous studies have not fully resolved site occupancy in lunar clinopyroxenes.
Purpose of the Study:
- To determine the site occupancy of ferrous iron, magnesium, and calcium in lunar clinopyroxenes.
- To investigate the cation ordering and its relationship to formation temperature.
- To analyze the microstructure of lunar clinopyroxene crystals.
Main Methods:
- Nuclear gamma-ray resonant absorption spectroscopy using (57)Fe.
- High-voltage electron microscopy (200 kv).
- Electron diffraction analysis.
- Diamond-knife ultramicrotomy for sample preparation.
Main Results:
- Estimated site occupancy numbers for Fe, Mg, and Ca at M1 and M2 sites.
- Demonstrated ordered cation distribution: Ca prefers M2, Mg prefers M1.
- Inferred equilibrium temperature below 680°C.
- Observed uniform 300-600 Å wide bands corresponding to single crystal domains.
Conclusions:
- The cation distribution in lunar clinopyroxenes is ordered and reflects a low-temperature equilibrium.
- Microstructural analysis revealed distinct single crystal domains within the samples.
- Further investigation is needed to correlate these domains with low-temperature magnetic ordering.
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