New nondestructive optical technique reveals the structure of mother-of-pearl

A camera and some iridescent shells

Most people know mother-of-pearl, an iridescent biomineral also called nacre, from buttons, jewelry, instrument inlays and other decorative flourishes. Scientists, too, have admired and marveled at nacre for decades, not only for its beauty and optical properties but because of its exceptional toughness.

“It’s one of the most-studied natural biominerals,” says Pupa Gilbert, a University of Wisconsin–Madison physics professor who has studied nacre for more than a decade. “It may not look like much — just a shiny, decorative material. But it can be 3,000 times more resistant to fracture than aragonite, the mineral from which it’s made. It has piqued the interest of materials scientists because making materials better than the sum of their parts is extremely attractive.”

Now, a new, nondestructive optical technique will unlock even more knowledge about nacre, and in the process could lead to a new understanding of climate history. Gilbert, UW–Madison electrical engineering professor Mikhail Kats — who is also an affiliate professor of physics — their students, and collaborators described the technique, called hyperspectral interference tomography, today in the journal Proceedings of the National Academy of Sciences.

Read the Full News Story | PNAS study

Pupa Gilbert elected Fellow of the Mineralogical Society of America

logo for the Mineralogical Society of America

Proflie photo of Pupa Gilbert

Congrats to Prof. Pupa Gilbert on her election as a Fellow of the Mineralogical Society of America! Members who have contributed significantly to the advancement of mineralogy, crystallography, geochemistry, petrology, or allied sciences and whose scientific contribution utilized mineralogical studies or data, may be designated as Fellows upon proper accreditation by the Committee on Nomination for Fellows and election by the Council. The number of fellows elected each year cannot exceed 0.5% of MSA membership.

Fellows newly elected in 2020 are Jeffrey Catalano, Sylvie Demouchy, Pupa Gilbert, Jun-ichi Kimura, Othmar Muntener, Marc Norman, Alison Pawley, Mark Rivers, Ian Swainson, and Takashi Yoshino.

Full list of MSA Fellows

A better understanding of coral skeleton growth suggests ways to restore reefs

Coral reefs are vibrant communities that host a quarter of all species in the ocean and are indirectly crucial to the survival of the rest. But they are slowly dying — some estimates say 30 to 50 percent of reefs have been lost — due to climate change.

In a new study, University of Wisconsin–Madison physicists observed reef-forming corals at the nanoscale and identified how they create their skeletons. The results provide an explanation for how corals are resistant to acidifying oceans caused by rising carbon dioxide levels and suggest that controlling water temperature, not acidity, is crucial to mitigating loss and restoring reefs.

“Coral reefs are currently threatened by climate change. It’s not in the future, it’s in the present,” says Pupa Gilbert, a physics professor at UW–Madison and senior author of the study. “How corals deposit their skeletons is fundamentally important to assess and help their survival.”

Read the Full Story | Link to the PNAS study