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cavansite

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Journal Article

Continuous dehydration of cavansite under dynamic conditions: an in situ synchrotron powder-diffraction study

Annalisa Martucci, Elisa Rodeghero, Giuseppe Cruciani
Published: 01 March 2016
European Journal of Mineralogy (2016) 28 (1): 5–13.
DOI: https://doi.org/10.1127/ejm/2015/0027-2512
...Annalisa Martucci; Elisa Rodeghero; Giuseppe Cruciani Abstract The dehydration dynamics of cavansite, Ca(VO)(Si 4 O 10 )·4H 2 O was studied by time-resolved in situ synchrotron powder diffraction between 298 and 900 K. The crystal-structure evolution was continuously monitored through twenty...
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Journal Article

In situ dehydration behavior of zeolite-like cavansite: A single-crystal X-ray study

Rosa Micaela Danisi, Thomas Armbruster, Biljana Lazic
Published: 01 November 2012
American Mineralogist (2012) 97 (11-12): 1874–1880.
DOI: https://doi.org/10.2138/am.2012.4228
...Rosa Micaela Danisi; Thomas Armbruster; Biljana Lazic Abstract To track dehydration behavior of cavansite, Ca(VO)(Si 4 O 10 )·4H 2 O [space group Pnma , a = 9.6329(2), b = 13.6606(2), c = 9.7949(2) Å, V = 1288.92(4) Å 3 ] single-crystal X-ray diffraction data on a crystal from Wagholi quarry, Poona...
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THE CRYSTAL STRUCTURE OF CAVANSITE: LOCATION OF THE H 2 O MOLECULES AND HYDROGEN ATOMS IN Ca(VO)(Si 4 O 10 )•4H 2 O

John M. Hughes, Rebecca S. Derr, Forrest Cureton, Charles F. Campana, Gregory Druschel
Published: 01 October 2011
The Canadian Mineralogist (2011) 49 (5): 1267–1272.
DOI: https://doi.org/10.3749/canmin.49.5.1267
...John M. Hughes; Rebecca S. Derr; Forrest Cureton; Charles F. Campana; Gregory Druschel Abstract Cavansite, Ca(VO)(Si 4 O 10 )•4H 2 O, is a novel layer silicate, dimorphous with pentagonite. The earlier determination of its structure did not yield the location of the hydrogen atoms or clear...
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Journal Article

Thermal behaviour of cavansite from Waghoi, India

Anant V. Phadke, Aditi Apte
Published: 01 September 1994
Mineralogical Magazine (1994) 58 (3): 501–505.
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Journal Article

Cavansite and pentagonite, new dimorphous calcium vanadium silicate minerals from Oregon

Lloyd W. Staples, Howard T. Evans, Jr., James R. Lindsay
Published: 01 June 1973
American Mineralogist (1973) 58 (5-6): 405–411.
...Lloyd W. Staples; Howard T. Evans, Jr.; James R. Lindsay Abstract Cavansite, Ca(VO) (Si 4 O 10 )·4H 2 O, a new mineral found in cavities and veinlets in basalt and vugs in tuff at Goble and at Owyhee Dam in Oregon, occurs as radiating greenish-blue prismatic crystals associated with calcite...
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The crystal structures of cavansite and pentagonite

Howard T. Evans, Jr.
Published: 01 June 1973
American Mineralogist (1973) 58 (5-6): 412–424.
...Howard T. Evans, Jr. Abstract Cavansite and pentagonite, dimorphs of Ca(VO) (Si 4 O 10 )· 4H 2 O found in Malheur County, Oregon, are both orthorhombic and represent novel, layer-silicate structure types. Zigzag pyroxene-like (SiO 3 ) n chains, joined laterally into sheets parallel to the a-c plane...
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Portion of the <span class="search-highlight">cavansite</span> structure focusing on Ca coordination. ( a ) Cavan...

Portion of the cavansite structure focusing on Ca coordination. ( a ) Cavan...

Published: 01 November 2012
Figure 3 Portion of the cavansite structure focusing on Ca coordination. ( a ) Cavansite at room temperature showing the hydrogen-bond system. The O9-H9a…O6 hydrogen bond is not shown because it points toward the observer. ( b ) Cavansite at 75 °C. The H 2 O molecule at O9 has been expelled
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Framework of <span class="search-highlight">cavansite</span> and channel occupants in space-group setting Pnma ;...

Framework of cavansite and channel occupants in space-group setting Pnma ;...

Published: 01 November 2012
Figure 2 Framework of cavansite and channel occupants in space-group setting Pnma ; ( a ) at 75 °C, ( b ) at 175 °C, and ( c ) at 350 °C. ( d ) Framework of cavansite by Rinaldi et al. (1975) showing only one H 2 O molecule (W1) after dehydration at 220 °C under vacuum, refined at room
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Selected powder patterns of <span class="search-highlight">cavansite</span> as a function of temperature.

Selected powder patterns of cavansite as a function of temperature.

Published: 01 March 2016
Fig. 2 Selected powder patterns of cavansite as a function of temperature.
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Framework of <span class="search-highlight">cavansite</span> at 298 K, 433 K, 542 K and 783 K, respectively.

Framework of cavansite at 298 K, 433 K, 542 K and 783 K, respectively.

Published: 01 March 2016
Fig. 8 Framework of cavansite at 298 K, 433 K, 542 K and 783 K, respectively.
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The spectrum of the VO 2+ ion in blue <span class="search-highlight">cavansite</span> from near Wagholi, Pune Di...

The spectrum of the VO 2+ ion in blue cavansite from near Wagholi, Pune Di...

Published: 01 January 2014
Figure 6 The spectrum of the VO 2+ ion in blue cavansite from near Wagholi, Pune District, Maharashtra, India plotted as 1.0 mm thick.
Image
Framework of <span class="search-highlight">cavansite</span> at room temperature. The green polyhedra represent S...

Framework of cavansite at room temperature. The green polyhedra represent S...

Published: 01 November 2012
Figure 1 Framework of cavansite at room temperature. The green polyhedra represent Si tetrahedra, while the yellow polyhedra are the V square-based pyramids. Calcium is in blue and oxygen of H 2 O are shown as light blue spheres with attached small white spheres representing H. Hydrogen-bond
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The silicate layer of the atomic arrangement in <span class="search-highlight">cavansite</span>. Gray polyhedra r...

The silicate layer of the atomic arrangement in cavansite. Gray polyhedra r...

Published: 01 October 2011
Fig. 1 The silicate layer of the atomic arrangement in cavansite. Gray polyhedra represent Si1 tetrahedra, which have apical oxygen atoms, O1, whereas the orange polyhedra represent Si2 tetrahedra with apical oxygen atoms, O2. The unit cell is shown.
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Structure of <span class="search-highlight">cavansite</span>, Ca(VO)(Si 4 O 10 )(H 2 O) 4 (a) and KNAURSI, KNa 3...

Structure of cavansite, Ca(VO)(Si 4 O 10 )(H 2 O) 4 (a) and KNAURSI, KNa 3...

Published: 01 January 2005
Figure 25. Structure of cavansite, Ca(VO)(Si 4 O 10 )(H 2 O) 4 (a) and KNAURSI, KNa 3 (UO 2 ) 2 (Si 4 O 10 ) 2 (H 2 O) 4 (b) are based upon Si 4 O 10 silicate sheets shown in (c,d) and (e,f), respectively. The sheets consist of 4- and 8-membered rings of tetrahedra and can designated using
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Kinked planar 4.8 2 sheets of u–d tetrahedra in ( a ) apophyllite and ( ...

Kinked planar 4.8 2 sheets of u–d tetrahedra in ( a ) apophyllite and ( ...

Published: 01 February 2019
Fig. 17. Kinked planar 4.8 2 sheets of u–d tetrahedra in ( a ) apophyllite and ( b ) cavansite .
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The Si and V–Ca layers join laterally to complete the crystal structure of ...

The Si and V–Ca layers join laterally to complete the crystal structure of ...

Published: 01 October 2011
Fig. 3 The Si and V–Ca layers join laterally to complete the crystal structure of cavansite. The colors of the tetrahedra are as in Figure 1 .
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Variation with temperature of the O5–O5 distances defining the short and lo...

Variation with temperature of the O5–O5 distances defining the short and lo...

Published: 01 March 2016
Fig. 5 Variation with temperature of the O5–O5 distances defining the short and long axes of the elliptically shaped eight-membered tetrahedral rings of the cavansite structure.
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Development of unit-cell volume vs. temperature for in situ dehydration exp...

Development of unit-cell volume vs. temperature for in situ dehydration exp...

Published: 01 November 2012
Figure 4 Development of unit-cell volume vs. temperature for in situ dehydration experiments of cavansite. With exception of the 350 °C data, the size of the symbols is larger than the associated e.s.d. values.
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Change of the water content as obtained from Rietveld structure refinements...

Change of the water content as obtained from Rietveld structure refinements...

Published: 01 March 2016
Fig. 3 Change of the water content as obtained from Rietveld structure refinements (grey broken line) and as calculated from the thermogravimetric analysis (grey dotted line) compared to the evolution of the cell volume of cavansite (continous line) as a function of temperature.
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Thermogravimetric (TG) and differential thermogravimetric (DTG) curves of c...

Thermogravimetric (TG) and differential thermogravimetric (DTG) curves of c...

Published: 01 March 2016
Fig. 1 Thermogravimetric (TG) and differential thermogravimetric (DTG) curves of cavansite from Poona (this work, continuous lines) compared to the TG curve digitized from Fig. 1a of Ishida et al. (2009) and the corresponding DTG curve (broken line). Differences in the DTG peak intensities