[1] Secondary calcite shelfstone deposits in caves can be used to precisely measure tilting over geologic timescales. Calcite deposited along the edges of former pools can be surveyed to within a single millimeter, and can be dated using uranium-series disequilibrium. Two caves in the southern Sierra Nevada, California, contain tilted calcite deposits of glacial age. A third cave contains a sim...

The crystal structure of calcite III has been deduced from existing high pressure powder X-ray diffraction patterns, based on the assumption that it is a displacive modification of the calcite I structure. The structure is monoclinic with space group C2 and a Z of 6. There are two Ca and two C positions, and five O positions, and atom coordinates have been refined by distance-least-squares meth...

calcite and possibly other carbonates which coat he surfaces of cleats. If the calcite is not removed by washing then it adds CaO lo that already in the ash. If the ash concentration is low then this addition of CaO can cause the concentration in the ash to rise markedly. The mineralogy of the ash ensures that it also contains some CaO. The concentration of this component of the CaO probably...

Calcite crystals were grown from solution with single-crystal dimensions up to 3 mm and doped up to 0.1 at% with Nd ions. Phase purity was verified by powder X-ray diffraction. The concentration of Nd was measured by energy-dispersive spectrometry and Rutherford backscattering spectrometry. Micro X-ray fluorescence mapping of the calcite grains indicates uniform Nd distribution in as-grown crys...

Novel rod-shaped calcite crystals are formed by precipitation from cetyltrimethylammonium bromide (CTAB)/1-pentanol/cyclohexane microemulsions containing calcium chloride and ammonium carbonate. The calcium carbonate initially precipitates as hexagon-shaped vaterite crystals. The vaterite crystals transform to unusual rod-shaped calcite crystals over several days. The rod-shaped calcite crystal...

The temperatures induced in crystalline calcite upon planar shock compression (95-160 GPa) are reported from two-stage light gas-gun experiments. The temperatures are obtained fitting 6channel optical pyrometer radiances in the 450 to 900 nm range, to a Planck radiation law temperature varied from 3300 to 5400 K. Calculations demonstrate that the temperatures are some 400 to 1350 K lower than i...

Calcite and aragonite are the two common polymorphs of CaCO3 observed as biominerals. It is universal that the sea water contents a high Mg (50mM) relative to Ca (10mM). In vivo crystallization, Mg inhibits calcite formation. For this reason, stony corals skeleton may be formed only aragonite crystals in the biocalcification. It is special in case of soft corals of which formed only calcite cry...

The micronucleus (MN) assay on exfoliated buccal cells is a useful and minimally invasive method for monitoring genetic damage in humans. To determine the genotoxic effects of calcite dust that forms during processing, MN assay was carried out in exfoliated buccal cells of 50 (25 smokers and 25 non-smokers) calcite factory workers and 50 (25 smokers and 25 non-smokers) age- and sex-matched cont...

Near-equilibrium calcite dissolution in seawater contributes significantly to the regulation of atmospheric [Formula: see text] on 1,000-y timescales. Despite many studies on far-from-equilibrium dissolution, little is known about the detailed mechanisms responsible for calcite dissolution in seawater. In this paper, we dissolve 13C-labeled calcites in natural seawater. We show that the time-ev...

Global databases of calcium carbonate concentrations and mass accumulation rates in Holocene and last glacial maximum sediments were used to estimate the deep-sea sedimentary calcium carbonate burial rate during these two time intervals. Sparse calcite mass accumulation rate data were extrapolated across regions of varying calcium carbonate concentration using a gridded map of calcium carbonate...