Zincalstibite-9R: the first nine-layer polytype with the layered double hydroxide structure-type
Abstract
Zincalstibite-9R, a new polytype in the hydrotalcite supergroup is reported from the Monte Avanza mine, Italy. It occurs as pale blue curved disc-like tablets flattened on {001} intergrown to form rosettes typically less than 50 μm in diameter, with cyanophyllite and linarite in cavities in baryte. Zincalstibite-9R is uniaxial (−), with refractive indices ω = 1.647(2) and ε = 1.626(2) measured in white light. The empirical formula (based on 12 OH groups) is (Zn^(2+)_(1.09)Cu^(2+)_(0.87)Al_(0.04))_(Σ2.00)Al_(1.01) (Sb^(5+)_(0.97)Si_(0.02))Σ_(0.99)(OH)_(12), and the ideal formula is (Zn,Cu)_2Al(OH)_6[Sb(OH)_6]. Zincalstibite-9R crystallizes in space group R3İ, with ɑ = 5.340(2), c = 88.01(2) Å, V = 2173.70(15) Å^3 and Z = 9. The crystal structure was refined to R_1 = 0.0931 for 370 unique reflections [F_o > 4σ(F)] and R_1 = 0.0944 for all 381 unique reflections. It has the longest periodic layer stacking sequence for a layered double hydroxide compound reported to date.
Additional Information
© 2012 The Mineralogical Society. Received 22 April 2012; Accepted 3 June 2012; Associate Editor: Elena Sokolova. An anonymous reviewer provided helpful comments on the manuscript and is thanked. Part of this study was funded by the John Jago Trelawney Endowment to the Mineral Sciences Department of the Natural History Museum of Los Angeles County. The microprobe analyses were supported by a grant to the California Institute of Technology from the Northern California Mineralogical Association. Sylvano Iob is thanked for providing the specimen for study.Attached Files
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Additional details
- Eprint ID
- 36490
- Resolver ID
- CaltechAUTHORS:20130122-085657179
- John Jago Trelawney Endowment
- Northern California Mineralogical Association
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2013-01-22Created from EPrint's datestamp field
- Updated
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2021-11-09Created from EPrint's last_modified field