Brearleyite, Ca12Al14O32Cl2, a new alteration mineral from the NWA 1934 meteorite

Chi Ma, Harold C. Connolly, John R. Beckett, Oliver Tschauner, George R. Rossman, Anthony R. Kampf, Thomas J. Zega, Stuart A. Sweeney Smith, Devin Schrader

Research output: Contribution to journalArticle

18 Citations (Scopus)

Abstract

Brearleyite (IMA 2010-062, Ca12Al14O 32Cl2) is a Cl-bearing mayenite, occurring as fine-grained aggregates coexisting with hercynite, gehlenite, and perovskite in a rare krotite (CaAl2O4) dominant refractory inclusion from the Northwest Africa 1934 CV3 carbonaceous chondrite. The phase was characterized by SEM, TEM-SAED, micro-Raman, and EPMA. The mean chemical composition of the brearleyite is (wt%) Al2O3 48.48, CaO 45.73, Cl 5.12, FeO 0.80, Na2O 0.12, TiO2 0.03, -2O 1.16 2, ∑ 99.12. The corresponding empirical formula calculated on the basis of 34 O+Cl atoms is (Ca11.91 Na0.06)?11.97(Al13.89Fe 0.16Ti0.01)σ14.06O31.89Cl2.11. The Raman spectrum of brealryeite indicates very close structural similarity to synthetic Ca12Al14O32Cl2. Rietveld refinement of an integrated TEM-SAED ring pattern from a FIB section quantifies this structural relationship and indicates that brearleyite is cubic, I43d; a = 11.98(8) Å, V = 1719.1(2) Å3, and Z = 2. It has a framework structure in which AlO4 tetrahedra share corners to form eight-membered rings. Within this framework, the Cl atom is located at a special position (3/8,0,1/4) with 0.4(2) occupancy and Ca appears to be disordered on two partially occupied sites similar to synthetic Cl-mayenite. Brearleyite has a light olive color under diffuse reflected light and a calculated density of 2.797 g/cm3. Brearleyite is not only a new meteoritic Ca-,Al-phase, but also a new meteoritic Cl-rich phase. It likely formed by the reaction of krotite with Cl-bearing hot gases or fluids.

Original languageEnglish (US)
Pages (from-to)1199-1206
Number of pages8
JournalAmerican Mineralogist
Volume96
Issue number8-9
DOIs
StatePublished - Aug 1 2011
Externally publishedYes

Fingerprint

Bearings (structural)
Meteorites
mineral alteration
meteorites
meteorite
Minerals
transmission electron microscopy
gehlenite
minerals
hercynite
Transmission electron microscopy
carbonaceous chondrites
Atoms
Rietveld refinement
carbonaceous chondrite
rings
perovskite
Electron probe microanalysis
high temperature gases
refractories

Keywords

  • Brearleyite
  • CaAlOC
  • Cl-bearing mayenite
  • CV3 carbonaceous chondrite
  • New mineral
  • NWA 1934 meteorite
  • Rietveld refinement
  • SAED ring pattern

ASJC Scopus subject areas

  • Geophysics
  • Geochemistry and Petrology

Cite this

Ma, C., Connolly, H. C., Beckett, J. R., Tschauner, O., Rossman, G. R., Kampf, A. R., ... Schrader, D. (2011). Brearleyite, Ca12Al14O32Cl2, a new alteration mineral from the NWA 1934 meteorite. American Mineralogist, 96(8-9), 1199-1206. https://doi.org/10.2138/am.2011.3755

Brearleyite, Ca12Al14O32Cl2, a new alteration mineral from the NWA 1934 meteorite. / Ma, Chi; Connolly, Harold C.; Beckett, John R.; Tschauner, Oliver; Rossman, George R.; Kampf, Anthony R.; Zega, Thomas J.; Sweeney Smith, Stuart A.; Schrader, Devin.

In: American Mineralogist, Vol. 96, No. 8-9, 01.08.2011, p. 1199-1206.

Research output: Contribution to journalArticle

Ma, C, Connolly, HC, Beckett, JR, Tschauner, O, Rossman, GR, Kampf, AR, Zega, TJ, Sweeney Smith, SA & Schrader, D 2011, 'Brearleyite, Ca12Al14O32Cl2, a new alteration mineral from the NWA 1934 meteorite', American Mineralogist, vol. 96, no. 8-9, pp. 1199-1206. https://doi.org/10.2138/am.2011.3755
Ma C, Connolly HC, Beckett JR, Tschauner O, Rossman GR, Kampf AR et al. Brearleyite, Ca12Al14O32Cl2, a new alteration mineral from the NWA 1934 meteorite. American Mineralogist. 2011 Aug 1;96(8-9):1199-1206. https://doi.org/10.2138/am.2011.3755
Ma, Chi ; Connolly, Harold C. ; Beckett, John R. ; Tschauner, Oliver ; Rossman, George R. ; Kampf, Anthony R. ; Zega, Thomas J. ; Sweeney Smith, Stuart A. ; Schrader, Devin. / Brearleyite, Ca12Al14O32Cl2, a new alteration mineral from the NWA 1934 meteorite. In: American Mineralogist. 2011 ; Vol. 96, No. 8-9. pp. 1199-1206.
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abstract = "Brearleyite (IMA 2010-062, Ca12Al14O 32Cl2) is a Cl-bearing mayenite, occurring as fine-grained aggregates coexisting with hercynite, gehlenite, and perovskite in a rare krotite (CaAl2O4) dominant refractory inclusion from the Northwest Africa 1934 CV3 carbonaceous chondrite. The phase was characterized by SEM, TEM-SAED, micro-Raman, and EPMA. The mean chemical composition of the brearleyite is (wt{\%}) Al2O3 48.48, CaO 45.73, Cl 5.12, FeO 0.80, Na2O 0.12, TiO2 0.03, -2O 1.16 2, ∑ 99.12. The corresponding empirical formula calculated on the basis of 34 O+Cl atoms is (Ca11.91 Na0.06)?11.97(Al13.89Fe 0.16Ti0.01)σ14.06O31.89Cl2.11. The Raman spectrum of brealryeite indicates very close structural similarity to synthetic Ca12Al14O32Cl2. Rietveld refinement of an integrated TEM-SAED ring pattern from a FIB section quantifies this structural relationship and indicates that brearleyite is cubic, I43d; a = 11.98(8) {\AA}, V = 1719.1(2) {\AA}3, and Z = 2. It has a framework structure in which AlO4 tetrahedra share corners to form eight-membered rings. Within this framework, the Cl atom is located at a special position (3/8,0,1/4) with 0.4(2) occupancy and Ca appears to be disordered on two partially occupied sites similar to synthetic Cl-mayenite. Brearleyite has a light olive color under diffuse reflected light and a calculated density of 2.797 g/cm3. Brearleyite is not only a new meteoritic Ca-,Al-phase, but also a new meteoritic Cl-rich phase. It likely formed by the reaction of krotite with Cl-bearing hot gases or fluids.",
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AU - Tschauner, Oliver

AU - Rossman, George R.

AU - Kampf, Anthony R.

AU - Zega, Thomas J.

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N2 - Brearleyite (IMA 2010-062, Ca12Al14O 32Cl2) is a Cl-bearing mayenite, occurring as fine-grained aggregates coexisting with hercynite, gehlenite, and perovskite in a rare krotite (CaAl2O4) dominant refractory inclusion from the Northwest Africa 1934 CV3 carbonaceous chondrite. The phase was characterized by SEM, TEM-SAED, micro-Raman, and EPMA. The mean chemical composition of the brearleyite is (wt%) Al2O3 48.48, CaO 45.73, Cl 5.12, FeO 0.80, Na2O 0.12, TiO2 0.03, -2O 1.16 2, ∑ 99.12. The corresponding empirical formula calculated on the basis of 34 O+Cl atoms is (Ca11.91 Na0.06)?11.97(Al13.89Fe 0.16Ti0.01)σ14.06O31.89Cl2.11. The Raman spectrum of brealryeite indicates very close structural similarity to synthetic Ca12Al14O32Cl2. Rietveld refinement of an integrated TEM-SAED ring pattern from a FIB section quantifies this structural relationship and indicates that brearleyite is cubic, I43d; a = 11.98(8) Å, V = 1719.1(2) Å3, and Z = 2. It has a framework structure in which AlO4 tetrahedra share corners to form eight-membered rings. Within this framework, the Cl atom is located at a special position (3/8,0,1/4) with 0.4(2) occupancy and Ca appears to be disordered on two partially occupied sites similar to synthetic Cl-mayenite. Brearleyite has a light olive color under diffuse reflected light and a calculated density of 2.797 g/cm3. Brearleyite is not only a new meteoritic Ca-,Al-phase, but also a new meteoritic Cl-rich phase. It likely formed by the reaction of krotite with Cl-bearing hot gases or fluids.

AB - Brearleyite (IMA 2010-062, Ca12Al14O 32Cl2) is a Cl-bearing mayenite, occurring as fine-grained aggregates coexisting with hercynite, gehlenite, and perovskite in a rare krotite (CaAl2O4) dominant refractory inclusion from the Northwest Africa 1934 CV3 carbonaceous chondrite. The phase was characterized by SEM, TEM-SAED, micro-Raman, and EPMA. The mean chemical composition of the brearleyite is (wt%) Al2O3 48.48, CaO 45.73, Cl 5.12, FeO 0.80, Na2O 0.12, TiO2 0.03, -2O 1.16 2, ∑ 99.12. The corresponding empirical formula calculated on the basis of 34 O+Cl atoms is (Ca11.91 Na0.06)?11.97(Al13.89Fe 0.16Ti0.01)σ14.06O31.89Cl2.11. The Raman spectrum of brealryeite indicates very close structural similarity to synthetic Ca12Al14O32Cl2. Rietveld refinement of an integrated TEM-SAED ring pattern from a FIB section quantifies this structural relationship and indicates that brearleyite is cubic, I43d; a = 11.98(8) Å, V = 1719.1(2) Å3, and Z = 2. It has a framework structure in which AlO4 tetrahedra share corners to form eight-membered rings. Within this framework, the Cl atom is located at a special position (3/8,0,1/4) with 0.4(2) occupancy and Ca appears to be disordered on two partially occupied sites similar to synthetic Cl-mayenite. Brearleyite has a light olive color under diffuse reflected light and a calculated density of 2.797 g/cm3. Brearleyite is not only a new meteoritic Ca-,Al-phase, but also a new meteoritic Cl-rich phase. It likely formed by the reaction of krotite with Cl-bearing hot gases or fluids.

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KW - SAED ring pattern

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