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Updated: Jul 12, 2026
09:13
Characterization of Ultra-fine Grained and Nanocrystalline Materials Using Transmission Kikuchi Diffraction
Published on: April 1, 2017
Evidence for multiple sources of diamond from primitive chondrites
Science (New York, N.Y.)
|November 22, 1991
Summary
Fine-grained diamonds in meteorites show variations in carbon and nitrogen isotopes linked to their host meteorite type. These intrinsic differences suggest heterogeneous distribution in the early solar nebula.
Area of Science:
- Cosmochemistry
- Planetary Science
- Materials Science
Background:
- Fine-grained diamonds are abundant circumstellar dust found in primitive meteorites.
- Their elemental and isotopic compositions are influenced by the host meteorite.
- Previous studies noted variations in diamond properties but lacked definitive explanations.
Purpose of the Study:
- To investigate the elemental and isotopic characteristics of fine-grained diamonds from different meteorite types.
- To determine the cause of variations in nitrogen content and carbon isotopic composition.
- To understand the formation and distribution of these diamonds in the early solar nebula.
Main Methods:
- Isolation of fine-grained diamonds from ordinary and CM2-type chondrites.
- Analysis of carbon and nitrogen isotopic compositions.
- Combustion experiments to study the carbon-to-nitrogen ratio evolution.
Main Results:
- Carbon isotopic compositions ranged from -32 to -38 per mil.
- Nitrogen abundance varied significantly (0.2 to 0.9 wt%) between meteorite types.
- Metamorphic degassing was ruled out as the primary cause for nitrogen differences.
Conclusions:
- The observed variations in diamond composition are likely inherited from their formation.
- Diamonds were heterogeneously distributed within the solar nebula during condensation.
- A hidden nitrogen carrier within the diamond cannot be excluded as a contributing factor.
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