1991 Fiscal Year Final Research Report Summary
Sulfide minerals and their genesis in meteorites
| Project/Area Number |
01540670
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
鉱物学(含岩石・鉱床学)
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| Research Institution | Osaka Sangyo University |
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Principal Investigator |
MORIMOTO Nobuo Osaka Sangyo University. Liberal Arts. Professor., 教養部, 教授 (10029829)
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| Co-Investigator(Kenkyū-buntansha) |
SAKAMOTO Kiyoko Osaka Sangyo University. Liberal Arts. Assistant., 教養部, 技術員
TANAKA Kazuo Osaka Sangyo University. Liberal Arts. Associate Professor., 教養部, 助教授 (80066927)
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| Project Period (FY) |
1989 – 1991
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| Keywords | Meteorite minerals / Phase transformation / Pyroxenes / Mullite / Superstructure / Solid solution / Antiphase domain structure / Nonstoichiometric composition |
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| Research Abstract |
Pyroxenes and mullite have been studied to elucidate the formation mechanism of the superstructures of the minerals in the common meteorites.
Pyroxenes of MgSiO_3 indicate that protoenstatite transforms to clinoenstatite or to enstatite through a periodic glide of a half of the unit translation along (100), resulting in the antiphase domain structures. In mullite, a nonstoichiometric silicate mineral, the ordering of oxygen vacancies connected with the substitution between Si and Al results in a complex incommensurate structure based on an antiphase domain structure.
Based on the studies of the superstructures of the silicate and sulfide minerals, their structural changes in transformation are summarized as follows ;
(1) Domains consisting of polyhedra of oxygen or sulfur atoms around metal atoms shift as structural units in the transformation and reconstruct new structures.
(2) In a new phase, the domains of a unit-cell scale form an antiphase domain structure in comparison with the original structure.
(3) In the minerals forming solid solution, each domain is separated by the boundary zone which is different in composition and structure with the domain and form incommensurate structures.
(4) In the minerals with nonstoichiometric composition, vacancy behaves as a component of a solid solution and builds an incommensurate structures based on an antiphase domain structure.
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