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Updated: Oct 10, 2025
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Published on: May 14, 2019
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The Crystal Structure of BaCa(CO3)2 (barytocalcite)
1Institute for Materials Research, National Bureau of Standards, Washington, D.C. 20234.
Summary
Barytocalcite (BaCa(CO3)2) crystal structure was refined, revealing a unique ABCABC cation layer stacking. This differs from calcite and aragonite, impacting carbonate group orientation and coordination environments for calcium and barium ions.
Area of Science:
- Crystallography
- Mineralogy
- Materials Science
Background:
- Barytocalcite (BaCa(CO3)2) is a carbonate mineral with a known crystal structure.
- Previous structural studies provide a basis for detailed redetermination.
Purpose of the Study:
- To redetermine and refine the crystal structure of barytocalcite.
- To compare the structural features of barytocalcite with calcite and aragonite phases of CaCO3.
Main Methods:
- Single-crystal X-ray diffraction was employed for structural analysis.
- The structure was refined using 1652 observed reflections with corrections for absorption, extinction, and dispersion.
Main Results:
- The barytocalcite structure was refined to R = 0.023 in space group P21/m.
- It exhibits an ABCABC cation layer stacking, distinct from calcite (ABC) and aragonite (ABAB).
- Carbonate (CO3) group orientations are similar to aragonite, differing by ~30° from calcite.
Conclusions:
- The refined structure provides precise details on cation coordination and CO3 group arrangements in barytocalcite.
- Structural comparison highlights differences in layer stacking and CO3 orientation among related carbonate polymorphs.
Keywords:
Aragonitebarium calcium carbonatecalcium carbonatecrystal structuresingle crystal x-ray diffractionMore Related Videos
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