The nacre layer, or mother of pearl, at the inner surface of the
abalone shell and of other mollusk shells and pearls (see images
below) has a fracture resistance 3000 times greater than that of
aragonite, the pure mineral of which it is composed. The toughening
effect is due to well-defined nanolayers of organics at the interfaces
between micro-tablets of aragonite (JD Currey 1977, 2005).
Nacre formation is poorly understood at the
molecular level, and this piqued our interest in this material,
exploring the organic-mineral interface (Gilbert 2005, Metzler 2010,
We strive to understand the fundamental mechanisms leading to the
formation of the beautiful, extraordinarily efficient, self-assembling
natural structures in nacre. We recently discovered a new
polarization-dependent imaging contrast (PIC) mechanism, also known as
linear dichroism. The PIC-mapping method we developed (DeVol 2014)
showed that adjacent stacks of co-oriented tablets have different
crystallographic c-axis orientations, and consequently the nacre
growth direction cannot be identified with the c-axis (Metzler
2007). The appearance of the columns also inspired new models for the
formation mechanism of nacre (Gilbert 2008).
Our hypothesis is that the physical structure of nacre is affected
by the environmental conditions at the time of nacre deposition. We
are currently exploring this possibility (Olson 2012, Olson 2012,
Gilbert 2015 in preparation).
We recently discovered that nacre forms via two amorphous precursor
phases, similar to those found in sea urchin biominerals, and not
proto-aragonite (DeVol 2015).
Polarization-dependent imaging contrast in a side view of red abalone nacre. Different gray levels correspond to different c-axis orientations with respect to the illuminating x-ray polarization vector. Immediately adjacent columns are mis-aligned in c-axis direction. Data from ref. 5.
GG Publications on Nacre
- P.U.P.A. Gilbert, Bradley H. Frazer and M. Abrecht.
The organic-mineral interface in biominerals.
Reviews in Mineralogy and Geochemistry. In: Molecular Geomicrobiology. Vol 59. JF Banfield, KH Nealson, J. Cervini-Silva (eds), Mineralogical Society of America, Washington DC, p 157-185 (2005). PDF
- Rebecca A. Metzler, Mike Abrecht, Ronke M. Olabisi, Daniel Ariosa, Christopher J. Johnson, Bradley H. Frazer, Susan N. Coppersmith, P.U.P.A. Gilbert.
Columnar Nacre Architecture and Possible Formation Mechanism.
Phys. Rev. Lett. 98, 268102-1/4 (2007). PDF Also featured in Science 317, 175 (2007). PDF
- Rebecca A. Metzler, Dong Zhou, Mike Abrecht, Jau-Wern Chiou, Jinghua Guo, Daniel Ariosa, Susan N. Coppersmith, P.U.P.A. Gilbert.
Polarization-dependent imaging contrast in abalone shells.
Phys. Rev. B. 77, 064110-1/9 (2008). PDF
- Dong Zhou, Rebecca A. Metzler, Tolek Tyliszczak, Jinghua Guo, Mike Abrecht, Susan N. Coppersmith, P.U.P.A. Gilbert.
Assignment of polarization-dependent peaks in carbon K-edge spectra from biogenic and geologic aragonite.
J. Phys. Chem. B 112, 13128-13135 (2008). PDF
- P.U.P.A. Gilbert, Rebecca A. Metzler, Dong Zhou, Andreas Scholl, Andrew Doran, Anthony Young, Martin Kunz, Nobumichi Tamura, Susan N. Coppersmith.
Gradual Ordering in Red Abalone Nacre.
J. Am. Chem. Soc. 130, 17519-17527 (2008). PDF SI
- S. N. Coppersmith, P.U.P.A. Gilbert and R. A. Metzler.
Theoretical characterization of a model of aragonite crystal orientation in red abalone nacre.
J. Phys. A: Math. Theor. 42, 125101 (2009). PDF
- RA Metzler, GA Tribello, M Parrinello, and PUPA Gilbert.
Asprich peptides are occluded in calcite and permanently disorder biomineral crystals.
J. Am. Chem. Soc. 132, 11585-11591 (2010). PDF
- RA Metzler, JS Evans, CE Killian, D. Zhou, TH Churchill, N Appathurai, SN Coppersmith, PUPA Gilbert.
Nacre Protein Fragment Templates Lamellar Aragonite Growth.
J. Am. Chem. Soc. 132, 6329-6334 (2010). PDF
- IC Olson, R Kozdon, JW Valley, and PUPA Gilbert.
Mollusk Shell Nacre Ultrastructure Correlates with Environmental Temperature and Pressure.
J. Am. Chem. Soc. 134, 7351-7358 (2012). COVER PDF
- IC Olson and PUPA Gilbert.
Aragonite crystal orientation in mollusk shell nacre may depend on temperature. The angle spread of crystalline aragonite tablets records the water temperature at which nacre was deposited by Pinctada margaritifera.
Faraday Discuss. 159, 421-432 (2012). PDF
- PUPA Gilbert.
Polarization-dependent Imaging Contrast (PIC) mapping reveals nanocrystal orientation patterns in carbonate biominerals.
J. Electr. Spectrosc. and Rel. Phenom. special issue on Photoelectron microscopy, Time-resolved pump-probe PES. Eds. M Kiskinova, A Scholl. Vol 185, pages 395-405 (2012). PDF
- IC Olson, AZ Blonsky, N Tamura, M Kunz, B Pokroy, CP Romao, MA White, and PUPA Gilbert.
Crystal nucleation and near-epitaxial growth in nacre.
J. Struct. Biol. 184, 454-463 (2013). COVER PDF
- RT DeVol, C-Y Sun, MA Marcus, SN Coppersmith, SCB Myneni, and PUPA Gilbert.
Nanoscale transforming mineral phases in fresh nacre.
J Am Chem Soc, 137, 13325-13333 (2015). PDF
Highlighted in Science 350, 648 (2015). PDF
Also see stories from UW NEWS July 2, 2007 by Jill Sakai
Mother-of-pearl: Classic beauty and remarkable strength
and October 20, 2015 by Terrance Devitt
Mother-of-pearl's genesis identified in mineral's transformation
click each for larger image and caption