THE CRYSTAL STRUCTURE OF VLADIMIRITE, WITH A REVISED CHEMICAL FORMULA, Ca4(AsO4)2(AsO3OH){middle dot}4H2O

Yang, Hexiong; Evans, Stanley H.; Downs, Robert T.; Jenkins, Robert M.

doi:10.3749/canmin.49.4.1055

Cited by 6 publications

(2 citation statements)

References 30 publications

(46 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Additionally, the well-resolved lower wavenumber band at 708 cm -1 in the pharmacolite spectrum, as well as the broad and weak bands at 760 cm -1 (vladimirite) and 720 cm -1 (picropharmacolite), are attributed to the ν(As-OH) modes. 134,135 The aforementioned significant findings remain consistent when examining the lower wavenumber bands (500 -335 cm -1 , Fig. 17) derived from the corresponding ν2 and ν4 modes (Table 3 in Ref.…”

Section: Pharmacolite Picropharmacolite and Vladimiritesupporting

confidence: 66%

“…It is worth mentioning that previous literature on vladimirite did not focus on precisely attributing the bands in this region, providing either stretching (ν1 + ν3) or bending (ν2 + ν4) charac-teristics of the resulting bands. 135 Additionally, the quality of the picropharmacolite Raman spectrum 136 was low and did not allow for the extraction of relevant spectra-structural information.…”

Section: Pharmacolite Picropharmacolite and Vladimiritementioning

confidence: 99%

See 1 more Smart Citation

Crossroads of vibrational (infrared and Raman) spectroscopy and X-ray powder diffraction in identification and characterization of some minerals – advantages and limitations. A review

Makreski,

Pejov,

Jovanovski

2024

Maced. J. Chem. Chem. Eng.

View full text Add to dashboard Cite

Many analytical methods have been successfully employed for the study of minerals, in particular, vibrational infrared (FTIR) and Raman spectroscopies and X-ray powder diffraction (XRPD). The advantages of the vibrational spectroscopic techniques for identifying and characterizing minerals include: rapid and versatile use; qualitative and quantitative chemical signatures; distinctive chemical fingerprint of a material; indirect determination of the crystal features (polymorphism, isomorphism, coordination, degree of deformation of structural polyhedra); small sample quantity (area less than 1 μm2 for Raman); wide coverage of 4,000 – 50 cm−1 region in a single scan; in situ and direct measurements without sample preparation; nondestructive use; etc. On the other hand, XRPD is a destructive technique that, depending on the method used and the density of the material, requires from a few micrograms up to around 5 grams of sample quantity for analysis. In spite of that, it is a rapid and powerful technique used in mineral studies with relatively straightforward interpretation of the results. During the last decade, portable X-ray powder diffractometers for the nondestructive analysis of art and archeological materials have been developed along with the portable and hand-held vibrational spectroscopy instrument. Here, some advantages and limitations in the process of the complementary use of FTIR and Raman vibrational spectroscopy and XRPD for identification and characterization of minerals are outlined.

show abstract

Section: Pharmacolite Picropharmacolite and Vladimiritesupporting

confidence: 66%

Section: Pharmacolite Picropharmacolite and Vladimiritementioning

confidence: 99%

Crossroads of vibrational (infrared and Raman) spectroscopy and X-ray powder diffraction in identification and characterization of some minerals – advantages and limitations. A review

Makreski,

Pejov,

Jovanovski

2024

Maced. J. Chem. Chem. Eng.

View full text Add to dashboard Cite

show abstract

Vibrational spectra of the rare‐occurring complex hydrogen arsenate minerals pharmacolite, picropharmacolite, and vladimirite: Dominance of Raman over IR spectroscopy to discriminate arsenate and hydrogen arsenate units

Makreski

Todorov

Makrievski

et al. 2018

J Raman Spectroscopy

View full text Add to dashboard Cite

This work represents the first complete experimental and theoretical study of the infrared (IR) spectra of pharmacolite, Ca(AsO3OH)·2H2O; vladimirite, Ca4(AsO3OH)(AsO4)2·4H2O; and picropharmacolite, Ca4Mg(AsO3OH)2(AsO4)2·11H2O. IR spectra, collected at both room and liquid nitrogen temperature, have shown similar spectral view among minerals in the region of ν1 to ν4 modes, surprisingly not involving complexity in vladimirite and picropharmacolite spectral view due to the presence of both AsO3OH and AsO4 units compared to pharmacolite where only AsO3OH units appear in the structure. On the other hand, vladimirite and picropharmacolite Raman spectra in the corresponding ν1 to ν4 region (955–350 cm−1) exhibit existence of 3 sets of 2 bands (6 in total) completely reflecting the existence of 3 symmetrically nonequivalent AsO4 groups in the structures of vladimirite and picropharmacolite (of which one is protonated) and only one set of ν1 to ν4 bands from the structurally equivalent AsO3OH units in the pharmacolite structure. The liquid nitrogen temperature IR spectra enabled to infer important information regarding the OH vibrational bands related to the AsO3OH groups and to the water molecules. Essentially, all bands in the vibrational spectra were assigned and correlated with the findings for a plethora of structurally similar complex hydrogen arsenate minerals. To support the tentative assignment of bands in the vibrational spectra, quantum theoretical calculations were performed within the framework of density functional theory. On the basis of theoretical calculations, a few reassignments of bands appearing in the OH stretching region are proposed. X‐ray powder diffraction was used to confirm authenticity of the title systems.

show abstract

Guérinite Ca6(HAsO4)3(AsO4)2∙10.5H2O – a revision of the mineral formula

Liebhart,

Rieck,

Giester

2024

Miner Petrol

View full text Add to dashboard Cite

A single crystal of guérinite from the Plaka Mine, Lavrion, Greece, was examined by X-ray diffraction. The mineral crystallizes in the monoclinic space group P21/n with unit cell parameters a = 17.628 (2), b = 6.728 (1), c = 23.384 (3) Å, β = 90.68 (1)°, V = 2773.4 (6) Å3. The originally reported mineral formula Ca5(HAsO4)2(AsO4)2∙9H2O, Z = 5 should be revised to Ca6(HAsO4)3(AsO4)2∙10.5H2O, Z = 4. Accordingly, guérinite is no longer considered a polymorph to ferrarisite. The structure is characterized by complex layers consisting of corner- and edge sharing of CaOn (n = 7, 8) polyhedra and arsenate groups. The connection between these units is achieved exclusively via hydrogen bonding.

show abstract

THE CRYSTAL STRUCTURE OF VLADIMIRITE, WITH A REVISED CHEMICAL FORMULA, Ca4(AsO4)2(AsO3OH){middle dot}4H2O

Cited by 6 publications

References 30 publications

Crossroads of vibrational (infrared and Raman) spectroscopy and X-ray powder diffraction in identification and characterization of some minerals – advantages and limitations. A review

Crossroads of vibrational (infrared and Raman) spectroscopy and X-ray powder diffraction in identification and characterization of some minerals – advantages and limitations. A review

Vibrational spectra of the rare‐occurring complex hydrogen arsenate minerals pharmacolite, picropharmacolite, and vladimirite: Dominance of Raman over IR spectroscopy to discriminate arsenate and hydrogen arsenate units

Guérinite Ca6(HAsO4)3(AsO4)2∙10.5H2O – a revision of the mineral formula

Contact Info

Product

Resources

About