Abstract
Calcite is one of the most ubiquitous minerals in the Earth’s crust and is mostly present as calcite or the slightly denser polymorph aragonite. In addition five different phases of CaCO3 (calcite II-VI), which display similar structural features as calcite, have been observed with increasing pressure in different experiments by several authors. Experimentally, the CaCO3-III and CaCO3-IIIb polymorphs have recently been observed by Merlini et al. (2012) applying pressures between 2.5-15 GPa on natural samples of calcite using single-crystal synchrotron X‑ray diffraction.
Here we report an occurrence of metastable authigenic CaCO3-III and CaCO3-IIIb nanocrystals for the first time in nature. Using transmission electron microscopy, idiomorphic, 50-150 nm sized crystals were observed within several meters from the surface in quaternary loess deposits in Central Asia.
Nanocrystals contain higher surface energy per volume compared to coarse-grained materials due to their larger surface area. The internal pressure of a solid, PS, is at equilibrium with the surface stress, which increases with decreasing particle size. We estimated internal pressures inside the observed nanocrystals between 2.54-4.06 GPa, assuming spherical crystals with 1 nm diameter and specific surface energies, between 1.27-2.03 J/m2 (Forbes et al. 2011).
© 2015 by Walter de Gruyter Berlin/Boston
Articles in the same Issue
- Highlights and Breakthroughs. Reaction pathways toward the formation of dolomite
- Highlights and Breakthroughs. Zircon dissolution and growth during metamorphism
- Review Paper. Linear partitioning in binary solutions: A review with a novel partitioning array
- Presidential Address. The many facets of apatite
- Thermal expansion of F-Cl apatite crystalline solutions
- Pieczkaite, ideally Mn5(PO4)3Cl, a new apatite-supergroup mineral from Cross Lake, Manitoba, Canada: Description and crystal structure
- First-principles prediction of pressure-enhanced defect segregation and migration at MgO grain boundaries
- Optical properties of siderite (FeCO3) across the spin transition: Crossover to iron-rich carbonates in the lower mantle
- Calculation of the energetics of water incorporation in majorite garnet
- Influence of hydration on 23Na, 27Al, and 29Si MAS-NMR spectra of sodium saponites and sodium micas
- Quantification of water in majoritic garnet
- How to make a planet: An introduction
- Modeling siderophile elements during core formation and accretion, and the role of the deep mantle and volatiles
- Optical constants of synthetic potassium, sodium, and hydronium jarosite
- A photoluminescence study of REE3+ emissions in radiation-damaged zircon
- Hydrothermal chloritization processes from biotite in the Toki granite, Central Japan: Temporal variations of of the compositions of hydrothermal fluids associated with chloritization
- Fayalite oxidation processes in Obsidian Cliffs rhyolite flow, Oregon
- Effect of pores and grain size on the elastic and piezoelectric properties of quartz-based materials
- A route for the direct crystallization of dolomite
- Very large differences in intramolecular D-H partitioning in hydrated silicate melts synthesized at upper mantle pressures and temperatures
- Temperature dependence of crystal structure of CaGeO3 high-pressure perovskite phase and experimental determination of its Debye temperatures studied by low- and hightemperature single-crystal X-ray diffraction
- Insights into the structure of mixed CO2/CH4 in gas hydrates
- Hydrous species in feldspars: A reassessment based on FTIR and SIMS
- An insight into the inverse transformation of realgar altered by light
- First evidence of CaCO3-III and CaCO3-IIIb high-pressure polymorphs of calcite: Authigenically formed in near surface sediments
- Surface transformations of platinum grains from Fifield, New South Wales, Australia
- Cation exchange capacity and water content of opal in sedimentary basins: Example from the Monterey Formation, California
- Impact of preparation method and chemical composition on physicochemical and photocatalytic properties of nano-dimensional magnetite-type materials
- Transition metal cation site preferences in forsterite (Mg2SiO4) determined from paramagnetically shifted NMR resonances
- Review. Routine characterization and interpretation of complex alkali feldspar intergrowths
- Letter. Experimental confirmation of high-temperature silicate liquid immiscibility in multicomponent ferrobasaltic systems
- Letter. Discovery of stishovite in Apollo 15299 sample
- Presentation of the 2014 Roebling Medal of the Mineralogical Society of America to Bernard J. Wood
- Acceptance of the 2014 Roebling Medal of the Mineralogical Society of America
- Presentation of the Dana Medal of the Mineralogical Society of America for 2015 to Marc Hirschmann
- Acceptance of the Dana Medal of the Mineralogical Society of America for 2015
- Presentation of the Mineralogical Society of America Award for 2014 to Fang-Zhen Teng
- Acceptance of the Mineralogical Society of America Award for 2014
- New Mineral Names
Articles in the same Issue
- Highlights and Breakthroughs. Reaction pathways toward the formation of dolomite
- Highlights and Breakthroughs. Zircon dissolution and growth during metamorphism
- Review Paper. Linear partitioning in binary solutions: A review with a novel partitioning array
- Presidential Address. The many facets of apatite
- Thermal expansion of F-Cl apatite crystalline solutions
- Pieczkaite, ideally Mn5(PO4)3Cl, a new apatite-supergroup mineral from Cross Lake, Manitoba, Canada: Description and crystal structure
- First-principles prediction of pressure-enhanced defect segregation and migration at MgO grain boundaries
- Optical properties of siderite (FeCO3) across the spin transition: Crossover to iron-rich carbonates in the lower mantle
- Calculation of the energetics of water incorporation in majorite garnet
- Influence of hydration on 23Na, 27Al, and 29Si MAS-NMR spectra of sodium saponites and sodium micas
- Quantification of water in majoritic garnet
- How to make a planet: An introduction
- Modeling siderophile elements during core formation and accretion, and the role of the deep mantle and volatiles
- Optical constants of synthetic potassium, sodium, and hydronium jarosite
- A photoluminescence study of REE3+ emissions in radiation-damaged zircon
- Hydrothermal chloritization processes from biotite in the Toki granite, Central Japan: Temporal variations of of the compositions of hydrothermal fluids associated with chloritization
- Fayalite oxidation processes in Obsidian Cliffs rhyolite flow, Oregon
- Effect of pores and grain size on the elastic and piezoelectric properties of quartz-based materials
- A route for the direct crystallization of dolomite
- Very large differences in intramolecular D-H partitioning in hydrated silicate melts synthesized at upper mantle pressures and temperatures
- Temperature dependence of crystal structure of CaGeO3 high-pressure perovskite phase and experimental determination of its Debye temperatures studied by low- and hightemperature single-crystal X-ray diffraction
- Insights into the structure of mixed CO2/CH4 in gas hydrates
- Hydrous species in feldspars: A reassessment based on FTIR and SIMS
- An insight into the inverse transformation of realgar altered by light
- First evidence of CaCO3-III and CaCO3-IIIb high-pressure polymorphs of calcite: Authigenically formed in near surface sediments
- Surface transformations of platinum grains from Fifield, New South Wales, Australia
- Cation exchange capacity and water content of opal in sedimentary basins: Example from the Monterey Formation, California
- Impact of preparation method and chemical composition on physicochemical and photocatalytic properties of nano-dimensional magnetite-type materials
- Transition metal cation site preferences in forsterite (Mg2SiO4) determined from paramagnetically shifted NMR resonances
- Review. Routine characterization and interpretation of complex alkali feldspar intergrowths
- Letter. Experimental confirmation of high-temperature silicate liquid immiscibility in multicomponent ferrobasaltic systems
- Letter. Discovery of stishovite in Apollo 15299 sample
- Presentation of the 2014 Roebling Medal of the Mineralogical Society of America to Bernard J. Wood
- Acceptance of the 2014 Roebling Medal of the Mineralogical Society of America
- Presentation of the Dana Medal of the Mineralogical Society of America for 2015 to Marc Hirschmann
- Acceptance of the Dana Medal of the Mineralogical Society of America for 2015
- Presentation of the Mineralogical Society of America Award for 2014 to Fang-Zhen Teng
- Acceptance of the Mineralogical Society of America Award for 2014
- New Mineral Names