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Addibischoffite, Ca_2Al_6Al_6O_(20), a new calcium aluminate mineral from the Acfer 214 CH carbonaceous chondrite: A new refractory phase from the solar nebula

Ma, Chi and Krot, Alexander N. and Nagashima, Kazuhide (2017) Addibischoffite, Ca_2Al_6Al_6O_(20), a new calcium aluminate mineral from the Acfer 214 CH carbonaceous chondrite: A new refractory phase from the solar nebula. American Mineralogist, 102 (7). pp. 1556-1560. ISSN 0003-004X. https://resolver.caltech.edu/CaltechAUTHORS:20170705-074134737

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Abstract

Addibischoffite (IMA 2015-006), Ca_2Al_6Al_6O_(20), is a new calcium aluminate mineral that occurs with hibonite, perovskite, kushiroite, Ti-kushiroite, spinel, melilite, anorthite, and FeNi-metal in the core of a Ca-Al-rich inclusion (CAI) in the Acfer 214 CH3 carbonaceous chondrite. The mean chemical composition of type addibischoffite measured by electron probe microanalysis is (wt%) Al_2O_3 44.63, CaO 15.36, SiO_2 14.62, V_2O_3 10.64, MgO 9.13, Ti_2O_3 4.70, FeO 0.46, total 99.55, giving rise to an empirical formula of (Ca_(2.00))(Al_(2.55)Mg_(1.73)V^(3+)_(1.08)Ti^(3+)_(0.50)Ca_(0.09)Fe^(2+)_(0.05))_(∑6.01)(Al_(4.14)Si_(1.86))O_(20). The general formula is Ca_2(Al,Mg,V,Ti)_6(Al,Si)_6O_(20). The end-member formula is Ca_2Al_6Al_6O_(20). Addibischoffite has the P1̄ aenigmatite structure with a = 10.367 Å, b = 10.756 Å, c = 8.895 Å, α = 106.0°, β = 96.0°, γ = 124.7°, V = 739.7 Å^3, and Z = 2, as revealed by electron backscatter diffraction. The calculated density using the measured composition is 3.41 g/cm^3. Addibischoffite is a new member of the warkite (Ca_2Sc_6Al_6O_(20)) group and a new refractory phase formed in the solar nebula, most likely as a result of crystallization from an ^(16)O-rich Ca, Al-rich melt under high-temperature (~1575 °C) and low-pressure (~10^(−4) to 10^(−5) bar) conditions in the CAI-forming region near the protosun, providing a new puzzle piece toward understanding the details of nebular processes. The name is in honor of Addi Bischoff, cosmochemist at University of Münster, Germany, for his many contributions to research on mineralogy of carbonaceous chondrites, including CAIs in CH chondrites.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.2138/am-2017-6032DOIArticle
http://ammin.geoscienceworld.org/content/102/7/1556PublisherArticle
Alternate Title:Addibischoffite, Ca2Al6Al6O20, a new calcium aluminate mineral from the Acfer 214 CH carbonaceous chondrite: A new refractory phase from the solar nebula
Additional Information:© 2017 Mineralogical Society of America. Manuscript Received November 28, 2016; Manuscript Accepted March 23, 2017; First Published on July 03, 2017. SEM, EBSD, and EPMA were carried out at the Geological and Planetary Science Division Analytical Facility, Caltech, which is supported in part by NSF grants EAR-0318518 and DMR-0080065. This work was also supported by NASA grant NNX15AH38G. We thank Guy Libourel for help in estimating liquidus temperature of the CAI melt. We thank Sara Russell, Jangmi Han, and associate editor Steve Simon for their constructive reviews.
Funders:
Funding AgencyGrant Number
NSFEAR-0318518
NSFDMR-0080065
NASANNX15AH38G
Issue or Number:7
Record Number:CaltechAUTHORS:20170705-074134737
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20170705-074134737
Official Citation:Addibischoffite, Ca2Al6Al6O20, a new calcium aluminate mineral from the Acfer 214 CH carbonaceous chondrite: A new refractory phase from the solar nebula Chi Ma, Alexander N. Krot, Kazuhide Nagashima American Mineralogist Jul 2017, 102 (7) 1556-1560; DOI: 10.2138/am-2017-6032
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:78746
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:07 Jul 2017 18:22
Last Modified:03 Oct 2019 18:11

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