APPLYING FULL-PATTERN RIETVELD REFINEMENT ANALYSES TO UNDERSTAND THE BIOMINERALIZATION MECHANISM OF CORAL SKELETONS AND HOW THEY RESPOND TO ENVIRONMENTAL STRESS (Invited Presentation)

The careers of Jeffrey Post and David Bish have had a profound impact on the field of mineralogy. Their contributions to full-pattern Rietveld Refinement analyses have paved the way for new quantitative crystallographic perspectives across many subfields of mineralogy, including the field of biomineralization. Inspired by Bish and Post (1993), we decided to apply quantitative full-pattern Rietveld Refinement analyses to aragonites from different origins to lend new insights into how bioaragonites, such as coral skeletons, form. Rather than focusing on the biological mechanism behind coral skeletal formation, we measured the end-products of biomineralization: the coral aragonite crystals. By combining unit cell parameters with trace element geochemical analyses, we discovered that coral aragonite crystals are crystallographically identical to synthetic aragonite crystals precipitated from seawater in a laboratory setting (Farfan et al. 2022). However, coral aragonite differs substantially from mollusk aragonite and geologically-formed aragonites. New analyses across the growth history of a single coral core reveals that coral aragonite unit cell parameters may be further applied to better understand how environmental stress signals are recorded in coral skeletons over time.

From sparkles to coral skeletons, in this presentation I will review some of the highlights of Jeffrey Post’s career at the Smithsonian National Museum of Natural History, some of the recent work that we have embarked upon together, and some of the future directions that will continue the legacy of Bish and Post’s work.

References:

Bish, D. L., & Post, J. E. (1993). Quantitative mineralogical analysis using the Rietveld full-pattern fitting method. American Mineralogist, 78(9-10), 932-940.

Farfan, G. A., Apprill, A., Cohen, A., DeCarlo, T. M., Post, J. E., Waller, R. G., & Hansel, C. M. (2022). Crystallographic and chemical signatures in coral skeletal aragonite. Coral Reefs, 41(1), 19-34.