Redetermination of the crystal structure of calcium sulphate dihydrate, CaSO4 · 2H2O

Boeyens, Jan C. A.; Ichharam, V. V. H.

doi:10.1524/ncrs.2002.217.jg.9

Cited by 32 publications

(21 citation statements)

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“…The crystal structures of the phases gypsum (CaSO 4 Á2H 2 O; Boeyens & Ichharam, 2002;Pedersen & Semmingsen, 1982), bassanite (CaSO 4 Á0.5H 2 O, calcium sulfate hemihydrate; Bezou et al, 1995;Weiss & Brä u, 2009), soluble anhydrite (CaSO 4 , AIII; Flö rke, 1952) and anhydrite (CaSO 4 , AII; Kirfel & Will, 1980;Hartman, 1989) are known in the CaSO 4 -H 2 O system under ambient pressure-temperature conditions. The phases have their greatest importance in the building material sector.…”

Section: Introductionmentioning

confidence: 99%

Water channel structure of bassanite at high air humidity: crystal structure of CaSO₄·0.625H₂O

Schmidt

Paschke

Freyer

et al. 2011

Acta Crystallogr B Struct Sci

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Structure analysis using single-crystal diffraction was carried out as a contribution to the dispute about the nature of the water channel structure of bassanite (CaSO(4)·0.5H(2)O). A recent result of Weiss & Bräu (2009) for the crystal structure of bassanite (monoclinic, space group C2) at ambient conditions of air humidity was confirmed. In the presence of high relative air humidity the crystal structure of bassanite transformed due to the incorporation of additional water of hydration. The crystal structure of CaSO(4)·0.625H(2)O was solved by single-crystal diffraction at 298 K and 75% relative air humidity. The experimental results provided an insight into both crystal structures. A model explaining the phase transition from CaSO(4)·0.625H(2)O to CaSO(4)·0.5H(2)O was derived. The monoclinic cell setting of CaSO(4)·0.5H(2)O and the trigonal cell setting of CaSO(4)·0.625H(2)O were confirmed by powder diffraction.

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Section: Introductionmentioning

confidence: 99%

Water channel structure of bassanite at high air humidity: crystal structure of CaSO₄·0.625H₂O

Schmidt

Paschke

Freyer

et al. 2011

Acta Crystallogr B Struct Sci

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“…Full-pattern fitting of XRD data is used to track loss of gypsum and formation FiGure 2. Library 1D diffraction patterns for gypsum (Boeyens and Ichharam 2002), bassanite (Bezou et al 1995), soluble anhydrite (g-anhydrite; Bezou et al 1995), and common anhydrite (Hawthorne and Ferguson 1975) at CheMin 2q resolution (~0.3°). CheMin detection limits for gypsum and bassanite are ~0.1 wt%; the detection limit for common Amma anhydrite is less favorable (~0.2 wt%) largely because this structure lacks distinctive reflections in the area with few peak overlaps below 20°.…”

Section: Accounting For the Sample Environment Inside Cheminmentioning

confidence: 99%

Gypsum, bassanite, and anhydrite at Gale crater, Mars

Vaniman

Martínez

Rampe

et al. 2018

American Mineralogist

118

102

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m. marTínez 2 , elizabeTh b. rampe 3 , Thomas F. brisTow 4 , DaviD F. blake 4 , alberT s. Yen 5 , DouGlas w. minG 3 , william rapin 6 , pierre-Yves meslin 7 , John michael morookian 5 , roberT T. Downs 8 , sTeve J. chipera 9 , richarD v. morris 3 , shaunna m. morrison 10 , allan h. Treiman 11 , cherie n. achilles 8 , kevin roberTson 12 , John p. GroTzinGer 6 , roberT m. hazen 10 , roGer c. wiens 13 , anD Dawn Y. sumner 14

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“…Match units for anhydrite were developed from crystallographic data of Hawthorne and Ferguson (1975) transformed from space group Amma (which uses c a b coordinate system) to Cmcm (which uses standard Mermann-Mauguin a b c coordinate system used by Channel 5 EBSD software). Match units for gypsum were developed from crystallographic data of Boeyens and Ichhram (2002) with space group C2/c. Full details of the crystallographic parameters for anhydrite and gypsum are given by (Hildyard et al, 2009, Table 3).…”

Section: Cpo Determinationmentioning

confidence: 99%

“…This methodology has been extensively applied to determine seismic properties of a wide range of rock types and geological settings (Mainprice and Nicolas, 1989;Burlini and Kunze, 2000;Valcke et al, 2006;Tatham, 2008;Tatham et al, 2008;Healy et al, 2009;Lloyd et al, 2009;Dempsey et al, 2011;Lloyd et al, 2011b,a;Ward et al, 2012;Almqvist et al, 2013). Studies on sedimentary rocks that have used this methodology are fewer and include works in clastic rocks (e.g., Louis et al, 2005;Valcke et al, 2006), polycrystalline synthetic and natural halite (e.g., Sun et al, 1991;Raymer et al, 2000a,b;Urai et al, 2008;Desbois et al, 2010), and on polycrystalline anhydrite (e.g., Boeyens and Ichhram, 2002;Hildyard et al, 2009). Other works consider calcite mylonite and micaceous carbonates (e.g., Burlini and Kunze, 2000;Wenk et al, 2004); all of which have found that fabrics and elastic properties of individual minerals contribute to the seismic character of a rock.…”

Section: Introductionmentioning

confidence: 99%

Exploring the relative contribution of mineralogy and CPO to the seismic velocity anisotropy of evaporites

Vargas‐Meleza

Healy

Alsop

et al. 2015

Journal of Structural Geology

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We present the influence of mineralogy and microstructure on the seismic velocity anisotropy of evaporites. Bulk elastic properties and seismic velocities are calculated for a suite of 20 natural evaporite samples, which consist mainly of halite, anhydrite, and gypsum. They exhibit strong fabrics as a result of tectonic and diagenetic processes. Sample mineralogy and crystallographic preferred orientation (CPO) were obtained with the electron backscatter diffraction (EBSD) technique and the data used for seismic velocity calculations. Bulk seismic properties for polymineralic evaporites were evaluated with a rock recipe approach. Ultrasonic velocity measurements were also taken on cube shaped samples to assess the contribution of grain-scale shape preferred orientation (SPO) to the total seismic anisotropy. The sample results suggest that CPO is responsible for a significant fraction of the bulk seismic properties, in agreement with observations from previous studies. Results from the rock recipe indicate that increasing modal proportion of anhydrite grains can lead to a greater seismic anisotropy of a halite-dominated rock. Conversely, it can lead to a smaller seismic anisotropy degree of a gypsum-dominated rock until an estimated threshold proportion after which anisotropy increases again. The difference between the predicted anisotropy due to CPO and the anisotropy measured with ultrasonic velocities is attributed to the SPO and grain boundary effects in these evaporites.

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Redetermination of the crystal structure of calcium sulphate dihydrate, CaSO4 · 2H2O

Cited by 32 publications

References 0 publications

Water channel structure of bassanite at high air humidity: crystal structure of CaSO₄·0.625H₂O

Water channel structure of bassanite at high air humidity: crystal structure of CaSO₄·0.625H₂O

Gypsum, bassanite, and anhydrite at Gale crater, Mars

Exploring the relative contribution of mineralogy and CPO to the seismic velocity anisotropy of evaporites

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Redetermination of the crystal structure of calcium sulphate dihydrate, CaSO4 · 2H2O

Cited by 32 publications

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Water channel structure of bassanite at high air humidity: crystal structure of CaSO4·0.625H2O

Water channel structure of bassanite at high air humidity: crystal structure of CaSO4·0.625H2O

Gypsum, bassanite, and anhydrite at Gale crater, Mars

Exploring the relative contribution of mineralogy and CPO to the seismic velocity anisotropy of evaporites

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Water channel structure of bassanite at high air humidity: crystal structure of CaSO₄·0.625H₂O

Water channel structure of bassanite at high air humidity: crystal structure of CaSO₄·0.625H₂O