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Download fileNanoscale Transforming Mineral Phases in Fresh Nacre
journal contribution
posted on 2015-12-17, 10:21 authored by Ross T. DeVol, Chang-Yu Sun, Matthew
A. Marcus, Susan N. Coppersmith, Satish C. B. Myneni, Pupa U.P.A. GilbertNacre,
or mother-of-pearl, the iridescent inner layer of many mollusk
shells, is a biomineral lamellar composite of aragonite (CaCO3) and organic sheets. Biomineralization frequently occurs
via transient amorphous precursor phases, crystallizing into the final
stable biomineral. In nacre, despite extensive attempts, amorphous
calcium carbonate (ACC) precursors have remained elusive. They were
inferred from non-nacre-forming larval shells, or from a residue of
amorphous material surrounding mature gastropod nacre tablets, and
have only once been observed in bivalve nacre. Here we present the
first direct observation of ACC precursors to nacre formation, obtained
from the growth front of nacre in gastropod shells from red abalone
(Haliotis rufescens), using synchrotron spectromicroscopy.
Surprisingly, the abalone nacre data show the same ACC phases that
are precursors to calcite (CaCO3) formation in sea urchin
spicules, and not proto-aragonite or poorly crystalline aragonite
(pAra), as expected for aragonitic nacre. In contrast, we find pAra
in coral.
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abalone nacre data showaragonitic nacregrowth frontgastropod shellsbivalve nacreprecursor phasesNanoscale Transforming Mineral PhasesACC phasescalcium carbonatenacre formationgastropod nacre tabletsACC precursorsFresh NacreNacremollusk shellssea urchin spiculesbiomineral lamellarsynchrotron spectromicroscopy