The crystal structure of a biogenic aragonite from the nacre of an ammonite shell
- Calgary
The crystal structure of a biogenic aragonite from the nacre of an ammonite shell was obtained using synchrotron high-resolution powder X-ray diffraction (HRPXRD) data and Rietveld structure refinement. The well-preserved ammonite sample is from Alberta, Canada, and is from the Cretaceous period. The aragonite structure was refined in space group Pmcn, Z = 4, and the cell parameters obtained are a = 4.96265(2), b = 7.97016(4), c = 5.74474(3) {angstrom}, and V = 227.222(2) {angstrom}{sup 3}. The chemical analyses indicate a formula of [Ca{sub 0.995}Sr{sub 0.004}Ba{sub 0.001}]{Sigma} = 1.0(CO{sub 3}). The average <Ca-O> and <C-O> distances are 2.5281(3) and 1.2871(6) {angstrom}, respectively, and the average <O-C-O> angle is 119.94(8){sup o}. The CO{sub 3} groups are non-planar. Based on crystal-structure data for biogenic and non-biogenic aragonite samples, aragonite from ammonite nacre has minimal structural distortions and is very similar to non-biogenic aragonite, in particular, a sample from Spain.
- Research Organization:
- Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
- Sponsoring Organization:
- FOREIGN
- OSTI ID:
- 1033013
- Journal Information:
- RSC Advances, Vol. 2, Issue 2
- Country of Publication:
- United States
- Language:
- ENGLISH
Similar Records
Crystal-structure analysis of four mineral samples of anhydrite, CaSO[subscript 4], using synchrotron high-resolution powder X-ray diffraction data
Temperature Dependence of the Structural Parameters in the Transformation of Aragonite to Calcite, as Determined from In Situ Synchrotron Powder X-ray-Diffratction Data