The boron geochemistry of coral skeletons reflects the dissolved inorganic carbon (DIC) chemistry of the calcification fluid from which the skeletons precipitates and may be a valuable tool to investigate the effects of climate change on coral calcification. In this paper I calculate the predicted B/Ca of aragonite precipitating from seawater based fluids as a function of pH, [DIC] and [Ca2+]. ...

Powder and single crystal Raman spectra of the two most common phases of calcium carbonate are calculated with ab initio techniques (using a "hybrid" functional and a Gaussian-type basis set) and measured both at 80 K and room temperature. Frequencies of the Raman modes are in very good agreement between calculations and experiments: the mean absolute deviation at 80 K is 4 and 8 cm(-1) for cal...

No. dima4496 Beamline(s): X22B Like many other biomineralized materials, nacre (mother-of-pearl) has a complicated, hierarchical microstructure with organization on length scales ranging from Ångstroms to microns. For example, the nacre of Red Abalone (Haliotis rufescens) is composed of bricks of aragonite (CaCO3) “mortared” in an organic composite. The crystallography of the mineral component ...

Molluscan bivalve hinge ligaments are composed of long needle-shaped aragonite crystals embedded in a protein matrix. These crystals are twinned and, in general, the twin forms a thin lamella through the center of the crystal.

The New Zealand blackfoot abalone, Haliotis iris Gmelin, is among the few gastropods that precipitate both calcite and aragonite in their shells. The location, composition, and thickness of these mineral layers may affect color, luster, and strength of the shell, which is locally important in jewelry manufacture. Skeletal mineralogy and shell structure of H. iris from three southern New Zealand...

The sediments of Ethiopian crater lakes have differentially sensitive palaeoclimate indicators that vary with time. Lake Tilo, in the south-central Rift Valley, shows a 10,000-year diatom and oxygen-isotope sequence that may be interpreted in terms of hydrochemical and hydrological responses to century-scale climate changes. The diatom record of lake salinity became sensitive to climate variabi...

Gastropod statoliths are spherical biocarbonates formed during their lifespan. The stability and homogeneity of these structures' mineral matrix was characterised along their radiuses, using Nassarius reticulatus as a model. Generally, they were proved to be bimineralic. Two of the three CaCO3 crystalline polymorphs occurring in biocarbonates - aragonite and calcite - coexist along statolith ra...

Calcium carbonate (CaCO3) is an abundant mineral that has several uses in paper [1], Portland cement [2] and steel making [3], as agricultural input for soil modification [4], and food additive in soy milk and dairy products. Due to its high biocompatibility, CaCO3 is also employed in many pharmaceutical (anti-acid, dietary supplement for child and postmenopausal women), biological (scaffolds f...

Nacre (mother-of-pearl), made of inorganic and organic constituents (95 vol% aragonite calcium carbonate (CaCO(3)) platelets and 5 vol% elastic biopolymers), possesses a unique combination of remarkable strength and toughness, which is compatible for conventional high performance materials. The excellent mechanical properties are related to its hierarchical structure and precisely designed orga...

Coral reefs are found within a limited range of environmental conditions or tolerance limits. Estimating these limits is a critical prerequisite for understanding the impacts of climate change on the biogeography of coral reefs. Here we used the diagnostic model ReefHab to determine the current environmental tolerance limits for coral reefs and the global distribution of potential coral reef ha...