Daria Wain | QUT Queensland University of Technology (original) (raw)

Papers by Daria Wain

Faculty of Science and Technology, Apr 1, 2006

1. A Thermogravimetric study of the alunites of sodium, potassium and ammonium. Thermochimica ... more 2006) A Thermogravimetric study of the alunites of sodium, potassium and ammonium. Thermochimica Acta 443:pp. 56-61.

Faculty of Science and Technology, 2007

Minerals in the rosasite mineral group namely rosasite, glaucosphaerite, kolwezite, mcguinnessite... more Minerals in the rosasite mineral group namely rosasite, glaucosphaerite, kolwezite, mcguinnessite have been studied by powder X-ray diffraction, scanning electron microscopy and infrared spectroscopy. X-ray diffraction shows the minerals to be complex mixtures with more than one rosasite mineral observed in each sample. SEM analysis shows the minerals to be fibrous in nature and the use of EDAX enabled the chemical composition of the minerals to be determined. The spectral patterns for the minerals rosasite, glaucosphaerite, kolwezite and mcguinnessite are similar to that of malachite implying the molecular structure is similar to malachite. A comparison is made with the spectrum of malachite. The rosasite mineral group is characterised by two OH stretching vibrations at 3401and3311cmAˋ1.Twointensebandsobservedat3401 and 3311 cm À1 . Two intense bands observed at 3401and3311cmAˋ1.Twointensebandsobservedat1096 and 1046 cm À1 are assigned to m 1 (CO 3 ) 2À symmetric stretching vibration and the d OH deformation mode. Multiple bands are found in the 800-900 and 650-750 cm À1 regions attributed to the m 2 and m 4 bending modes confirming the symmetry reduction of the carbonate anion in the rosasite mineral group as C 2v or C s . A band at $560 cm À1 is assigned to a CuO stretching mode.

Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy, 2007

The ability of near infrared reflectance spectroscopy to classify the rosasite group minerals fro... more The ability of near infrared reflectance spectroscopy to classify the rosasite group minerals from spectral characteristics is demonstrated. NIR spectroscopy can be regarded as an alternative tool for structure analysis. The spectra show that rosasite group minerals with different cations can be distinguished. Ni2+ in nullaginite [Ni2(CO3)(OH)2] is conspicuous through a single broad band absorption feature at 8525 cm-1, extended from 11,000 to 7000 cm-1. The effect of Ni on Cu is seen in the spectrum of glaukosphaerite [(Cu, Ni)2(CO3)(OH)2] both by a red shift of the spectrum and reduction in intensity of bands with variable positions of band maxima for Cu2+ at 6995 cm-1 and Ni2+ at 7865 cm-1. The spectrum of rosasite [(Cu, Zn)2(CO)3(OH)2] is characterised by Cu2+ band at 7535 cm-1. Kolwezite [(Cu, Co)2(CO)3(OH)2] is a spectral mixture of Cu and Co but optically separated by Co2+ and Cu2+ peaks at 8385 and 7520 cm-1. Vibrational spectra of carbonates show a number of bands in the 70...

Thermochimica Acta, 2007

Two evaporite minerals from the El Jaroso Ravine, Spain have been analysed by thermogravimetry co... more Two evaporite minerals from the El Jaroso Ravine, Spain have been analysed by thermogravimetry coupled with an evolved gas mass spectrometer. X-ray diffraction results proved the evaporite minerals were a mixture of sulphates including the minerals magnesiocopiapite, coquimbite and possibly alunogen. Thermal decomposition of the unoxidised samples showed steps at 52, 99 and 143 • C confirmed by mass spectrometric results and attributed to adsorbed water, interstitial water and chemically bonded water. This evaporite mineral rock showed two higher temperature decomposition steps at 555 and 599 • C with mass losses of 19.6 and 7.8%. Slightly different temperatures for the thermal decomposition of the oxadada sample were observed at 52, 64.5 and 100 • C. Two higher temperature mass loss steps at 560.5 and 651 • C were observed for the oxidised sample. By comparison of the thermal analysis patterns of halotrichite and jarosite it can be shown that the El Jaroso samples are mineral sulphates and not halotrichite or jarosite.

Thermochimica Acta, 2006

1. A Thermogravimetric study of the alunites of sodium, potassium and ammonium. Thermochimica ... more 2006) A Thermogravimetric study of the alunites of sodium, potassium and ammonium. Thermochimica Acta 443:pp. 56-61.

Vibrational Spectroscopy, 2007

Electronic and vibrational spectra of two different tourmalines: green and pink coloured minerals... more Electronic and vibrational spectra of two different tourmalines: green and pink coloured minerals from Minas Gerais, Brazil have been investigated by UV-visible, NIR, IR and Raman spectroscopy. The behaviour of transition metal ions in their electronic spectra is presented. Both minerals show a strong broad band at ~300 nm (33300 cm -1 ) due to Mn(II) ion. In pink tourmaline three sharp bands at 365, 345, and 295 nm (27400, 28990 and 33900 cm -1 ) are assigned to 6 A 1g (S) → 4 T 2g (D), 6 A 1g (S) → 4 E g (D) and 6 A 1g (S) → 4 T 1g (F) transitions of Mn(II) ion. The pink colour arises from Mn(II) ion while the band at 520 nm comes from Mn(III) ion which acts as an aid to the transmission window from 700-to-900 nm in pink tourmaline. NIR spectroscopy provides evidence for Fe(II) through the observation of two bands at • Author to whom correspondence should be addressed (r.frost@qut.edu.au) P: +61 7 3864 2407 F: +61 7 3864 1804 2 10240 and 8000 cm -1 . The observation of four OH stretching bands in the hydroxyl stretching region 3800 to 3200 cm -1 near 3650, 3600 and 3555 and 3460 cm -1 shows mixed occupancy of octahedral sites in the minerals studied. The band positions in the spectra of green and pink tourmalines differ slightly due to variations in composition.

Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2008

Near-infrared spectroscopy (NIR) has been used to analyse alunites of formula K(Al3+)6(SO4)4(OH)1... more Near-infrared spectroscopy (NIR) has been used to analyse alunites of formula K(Al3+)6(SO4)4(OH)12. Whilst the spectra of the alunites shows a common pattern differences in the spectra are observed which enable the minerals to be distinguished. These differences are attributed to subtle variations in alunite composition. The NIR bands in the 6300-7000 cm(-1) region are attributed to the first fundamental overtone of both the infrared and Raman hydroxyl stretching vibrations. A set of bands are observed in the 4700-5500 cm(-1) region which are assigned to combination bands of the hydroxyl stretching and deformation vibrations. NIR spectroscopy has the ability to distinguish between the alunite minerals even when the formula of the minerals is closely related. The NIR spectroscopic technique has great potential as a mineral exploratory tool on planets and in particular Mars.

Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2007

The ability of near infrared reflectance spectroscopy to classify the rosasite group minerals fro... more The ability of near infrared reflectance spectroscopy to classify the rosasite group minerals from spectral characteristics is demonstrated. NIR spectroscopy can be regarded as an alternative tool for structure analysis. The spectra show that rosasite group minerals with different cations can be distinguished. Ni2+ in nullaginite [Ni2(CO3)(OH)2] is conspicuous through a single broad band absorption feature at 8525 cm-1, extended from 11,000 to 7000 cm-1. The effect of Ni on Cu is seen in the spectrum of glaukosphaerite [(Cu, Ni)2(CO3)(OH)2] both by a red shift of the spectrum and reduction in intensity of bands with variable positions of band maxima for Cu2+ at 6995 cm-1 and Ni2+ at 7865 cm-1. The spectrum of rosasite [(Cu, Zn)2(CO)3(OH)2] is characterised by Cu2+ band at 7535 cm-1. Kolwezite [(Cu, Co)2(CO)3(OH)2] is a spectral mixture of Cu and Co but optically separated by Co2+ and Cu2+ peaks at 8385 and 7520 cm-1. Vibrational spectra of carbonates show a number of bands in the 7000-4000 cm-1 region attributable to overtones, combination of OH stretching and deformation modes. They appear to be uniform in nature since the structure of rosasite group minerals is identical. The complexity of these features varies between samples because of the variation in composition and hence is useful for discriminating different hydrous carbonates.

Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2007

Minerals in the rosasite group namely rosasite, glaucosphaerite, kolwezite, mcguinnessite have be... more Minerals in the rosasite group namely rosasite, glaucosphaerite, kolwezite, mcguinnessite have been studied by a combination of infrared and Raman spectroscopy. The spectral patterns for the minerals rosasite, glaucosphaerite, kolwezite and mcguinnessite are similar to that of malachite implying the molecular structure is similar to malachite. A comparison is made with the spectrum of malachite. The rosasite mineral group is characterised by two OH stretching vibrations at approximately 3401 and 3311 cm-1. Two intense bands observed at approximately 1096 and 1046 cm-1 are assigned to nu1(CO3)2- symmetric stretching vibration and the delta OH deformation mode. Multiple bands are found in the 800-900 and 650-750 cm-1 regions attributed to the nu2 and nu4 bending modes confirming the symmetry reduction of the carbonate anion in the rosasite mineral group as C2v or Cs. A band at approximately 560 cm-1 is assigned to a CuO stretching mode.

Polyhedron, 2007

Minerals in the rosasite mineral group namely rosasite, glaucosphaerite, kolwezite, mcguinnessite... more Minerals in the rosasite mineral group namely rosasite, glaucosphaerite, kolwezite, mcguinnessite have been studied by powder X-ray diffraction, scanning electron microscopy and infrared spectroscopy. X-ray diffraction shows the minerals to be complex mixtures with more than one rosasite mineral observed in each sample. SEM analysis shows the minerals to be fibrous in nature and the use of EDAX enabled the chemical composition of the minerals to be determined. The spectral patterns for the minerals rosasite, glaucosphaerite, kolwezite and mcguinnessite are similar to that of malachite implying the molecular structure is similar to malachite. A comparison is made with the spectrum of malachite. The rosasite mineral group is characterised by two OH stretching vibrations at 3401and3311cmAˋ1.Twointensebandsobservedat3401 and 3311 cm À1 . Two intense bands observed at 3401and3311cmAˋ1.Twointensebandsobservedat1096 and 1046 cm À1 are assigned to m 1 (CO 3 ) 2À symmetric stretching vibration and the d OH deformation mode. Multiple bands are found in the 800-900 and 650-750 cm À1 regions attributed to the m 2 and m 4 bending modes confirming the symmetry reduction of the carbonate anion in the rosasite mineral group as C 2v or C s . A band at $560 cm À1 is assigned to a CuO stretching mode.

Journal of Thermal Analysis and Calorimetry, 2008

Thermogravimetric and differential thermogravimetric analysis has been used to characterize aluni... more Thermogravimetric and differential thermogravimetric analysis has been used to characterize alunite of formula [K 2 (Al 3+ ) 6 (SO 4 ) 4 (OH) 12 ]. Thermal decomposition occurs in a series of steps (a) dehydration up to 225°C, (b) well defined dehydroxylation at 520°C and desulphation which takes place as a series of steps at 649, 685 and 744°C.

Journal of Raman Spectroscopy, 2008

Raman spectroscopy at both 298 and 77 K has been used to study a series of selected natural smith... more Raman spectroscopy at both 298 and 77 K has been used to study a series of selected natural smithsonites from different origins. An intense sharp band at 1092 cm −1 is assigned to the CO 3 2− symmetric stretching vibration. Impurities of hydrozincite are identified by a band around 1060 cm −1 . An additional band at 1088 cm −1 which is observed in the 298 K spectra but not in the 77 K spectra is attributed to a CO 3 2− hot band. Raman spectra of smithsonite show a single band in the 1405-1409 cm −1 range assigned to the n 3 (CO 3 ) 2− antisymmetric stretching mode. The observation of additional bands for the n 3 g modes for some smithsonites is significant in that it shows distortion of the ZnO 6 octahedron. No n 2 bending modes are observed for smithsonite. A single band at 730 cm −1 is assigned to the n 4 in phase bending mode. Multiple bands be attributed to the structural distortion are observed for the carbonate n 4 in phase bending modes in the Raman spectrum of hydrozincite with bands at 733, 707 and 636 cm −1 . An intense band at 304 cm −1 is attributed to the ZnO symmetric stretching vibration.

Journal of Near Infrared Spectroscopy, 2006

A suite of sulphate effl orescent minerals from the El Jaroso ravine, Sierra Almagrera, Spain hav... more A suite of sulphate effl orescent minerals from the El Jaroso ravine, Sierra Almagrera, Spain have been analysed by ultraviolet, visible, NIR and mid infrared (IR) spectroscopy. Such a suite of minerals may be used to model the types of mineral deposits on Mars. The minerals were analysed by scanning electron microscopy and X-ray microanalysis (EDX) before spectroscopic analysis. Halotrichite was observed and the EDX analyses showed the mineral to be a mixture of heinrichite and pickingerite. The NIR spectrum of the efl orescencia sample showed the sulphate deposit to be composed of a mixture of jarosite and halotrichites. The 7400 to 6400 cm -1 (1351 to 1562 nm) NIR spectral region of the effl orescent sulphate minerals can be used to characterise the various sulphate deposits. The detection of a band at 8338 cm -1 (1199 nm) reveals the presence of ferrous iron in jarosite which is unusual for the jarosite minerals. This can be caused by ferric iron reduction by thermophilic iron-oxidising bacteria. Mid IR spectra showed the characteristic OH stretching bands of the jarosites and the effl orescent mixtures. The position of water stretching vibrations at 2900 cm -1 and lower shows strong hydrogen bonding as is also evidenced by water bending modes at around 1682 cm -1 .

Journal of Near Infrared Spectroscopy, 2008

The importance of NIR spectroscopy has been successfully demonstrated in the present study of smi... more The importance of NIR spectroscopy has been successfully demonstrated in the present study of smithsonite minerals. The fundamental observations in the NIR spectra, in addition to the anions of OH-and CO32-are Fe and Cu in terms of cation content. These ions ...

Journal of Magnetism and Magnetic Materials, 2013

Spectrochimica Acta Part A-molecular and Biomolecular Spectroscopy, 2008

The mineral nesquehonite Mg(OH)(HCO 3 )·2H 2 O has been analysed by a combination of infrared (IR... more The mineral nesquehonite Mg(OH)(HCO 3 )·2H 2 O has been analysed by a combination of infrared (IR) and infrared emission spectroscopy (IES). Both techniques show OH vibrations, both stretching and deformation modes. IES proves the OH units are stable up to 450 • C. The strong IR band at 934 cm −1 is evidence for MgOH deformation modes supporting the concept of HCO 3 − units in the molecular structure. Infrared bands at 1027, 1052 and 1098 cm −1 are attributed to the symmetric stretching modes of HCO 3 − and CO 3 2− units. Infrared bands at 1419, 1439, 1511, and 1528 cm −1 are assigned to the antisymmetric stretching modes of CO 3 2− and HCO 3 − units. IES supported by thermoanalytical results defines the thermal stability of nesquehonite. IES defines the changes in the molecular structure of nesquehonite with temperature. The results of IR and IES supports the concept that the formula of nesquehonite is better defined as Mg(OH)(HCO 3 )·2H 2 O.

Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2011

The mineral nesquehonite Mg(OH)(HCO 3 )·2H 2 O has been analysed by a combination of infrared (IR... more The mineral nesquehonite Mg(OH)(HCO 3 )·2H 2 O has been analysed by a combination of infrared (IR) and infrared emission spectroscopy (IES). Both techniques show OH vibrations, both stretching and deformation modes. IES proves the OH units are stable up to 450 • C. The strong IR band at 934 cm −1 is evidence for MgOH deformation modes supporting the concept of HCO 3 − units in the molecular structure. Infrared bands at 1027, 1052 and 1098 cm −1 are attributed to the symmetric stretching modes of HCO 3 − and CO 3 2− units. Infrared bands at 1419, 1439, 1511, and 1528 cm −1 are assigned to the antisymmetric stretching modes of CO 3 2− and HCO 3 − units. IES supported by thermoanalytical results defines the thermal stability of nesquehonite. IES defines the changes in the molecular structure of nesquehonite with temperature. The results of IR and IES supports the concept that the formula of nesquehonite is better defined as Mg(OH)(HCO 3 )·2H 2 O.

Faculty of Science and Technology, Apr 1, 2006

1. A Thermogravimetric study of the alunites of sodium, potassium and ammonium. Thermochimica ... more 2006) A Thermogravimetric study of the alunites of sodium, potassium and ammonium. Thermochimica Acta 443:pp. 56-61.

Faculty of Science and Technology, 2007

Minerals in the rosasite mineral group namely rosasite, glaucosphaerite, kolwezite, mcguinnessite... more Minerals in the rosasite mineral group namely rosasite, glaucosphaerite, kolwezite, mcguinnessite have been studied by powder X-ray diffraction, scanning electron microscopy and infrared spectroscopy. X-ray diffraction shows the minerals to be complex mixtures with more than one rosasite mineral observed in each sample. SEM analysis shows the minerals to be fibrous in nature and the use of EDAX enabled the chemical composition of the minerals to be determined. The spectral patterns for the minerals rosasite, glaucosphaerite, kolwezite and mcguinnessite are similar to that of malachite implying the molecular structure is similar to malachite. A comparison is made with the spectrum of malachite. The rosasite mineral group is characterised by two OH stretching vibrations at 3401and3311cmAˋ1.Twointensebandsobservedat3401 and 3311 cm À1 . Two intense bands observed at 3401and3311cmAˋ1.Twointensebandsobservedat1096 and 1046 cm À1 are assigned to m 1 (CO 3 ) 2À symmetric stretching vibration and the d OH deformation mode. Multiple bands are found in the 800-900 and 650-750 cm À1 regions attributed to the m 2 and m 4 bending modes confirming the symmetry reduction of the carbonate anion in the rosasite mineral group as C 2v or C s . A band at $560 cm À1 is assigned to a CuO stretching mode.

Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy, 2007

The ability of near infrared reflectance spectroscopy to classify the rosasite group minerals fro... more The ability of near infrared reflectance spectroscopy to classify the rosasite group minerals from spectral characteristics is demonstrated. NIR spectroscopy can be regarded as an alternative tool for structure analysis. The spectra show that rosasite group minerals with different cations can be distinguished. Ni2+ in nullaginite [Ni2(CO3)(OH)2] is conspicuous through a single broad band absorption feature at 8525 cm-1, extended from 11,000 to 7000 cm-1. The effect of Ni on Cu is seen in the spectrum of glaukosphaerite [(Cu, Ni)2(CO3)(OH)2] both by a red shift of the spectrum and reduction in intensity of bands with variable positions of band maxima for Cu2+ at 6995 cm-1 and Ni2+ at 7865 cm-1. The spectrum of rosasite [(Cu, Zn)2(CO)3(OH)2] is characterised by Cu2+ band at 7535 cm-1. Kolwezite [(Cu, Co)2(CO)3(OH)2] is a spectral mixture of Cu and Co but optically separated by Co2+ and Cu2+ peaks at 8385 and 7520 cm-1. Vibrational spectra of carbonates show a number of bands in the 70...

Thermochimica Acta, 2007

Two evaporite minerals from the El Jaroso Ravine, Spain have been analysed by thermogravimetry co... more Two evaporite minerals from the El Jaroso Ravine, Spain have been analysed by thermogravimetry coupled with an evolved gas mass spectrometer. X-ray diffraction results proved the evaporite minerals were a mixture of sulphates including the minerals magnesiocopiapite, coquimbite and possibly alunogen. Thermal decomposition of the unoxidised samples showed steps at 52, 99 and 143 • C confirmed by mass spectrometric results and attributed to adsorbed water, interstitial water and chemically bonded water. This evaporite mineral rock showed two higher temperature decomposition steps at 555 and 599 • C with mass losses of 19.6 and 7.8%. Slightly different temperatures for the thermal decomposition of the oxadada sample were observed at 52, 64.5 and 100 • C. Two higher temperature mass loss steps at 560.5 and 651 • C were observed for the oxidised sample. By comparison of the thermal analysis patterns of halotrichite and jarosite it can be shown that the El Jaroso samples are mineral sulphates and not halotrichite or jarosite.

Thermochimica Acta, 2006

1. A Thermogravimetric study of the alunites of sodium, potassium and ammonium. Thermochimica ... more 2006) A Thermogravimetric study of the alunites of sodium, potassium and ammonium. Thermochimica Acta 443:pp. 56-61.

Vibrational Spectroscopy, 2007

Electronic and vibrational spectra of two different tourmalines: green and pink coloured minerals... more Electronic and vibrational spectra of two different tourmalines: green and pink coloured minerals from Minas Gerais, Brazil have been investigated by UV-visible, NIR, IR and Raman spectroscopy. The behaviour of transition metal ions in their electronic spectra is presented. Both minerals show a strong broad band at ~300 nm (33300 cm -1 ) due to Mn(II) ion. In pink tourmaline three sharp bands at 365, 345, and 295 nm (27400, 28990 and 33900 cm -1 ) are assigned to 6 A 1g (S) → 4 T 2g (D), 6 A 1g (S) → 4 E g (D) and 6 A 1g (S) → 4 T 1g (F) transitions of Mn(II) ion. The pink colour arises from Mn(II) ion while the band at 520 nm comes from Mn(III) ion which acts as an aid to the transmission window from 700-to-900 nm in pink tourmaline. NIR spectroscopy provides evidence for Fe(II) through the observation of two bands at • Author to whom correspondence should be addressed (r.frost@qut.edu.au) P: +61 7 3864 2407 F: +61 7 3864 1804 2 10240 and 8000 cm -1 . The observation of four OH stretching bands in the hydroxyl stretching region 3800 to 3200 cm -1 near 3650, 3600 and 3555 and 3460 cm -1 shows mixed occupancy of octahedral sites in the minerals studied. The band positions in the spectra of green and pink tourmalines differ slightly due to variations in composition.

Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2008

Near-infrared spectroscopy (NIR) has been used to analyse alunites of formula K(Al3+)6(SO4)4(OH)1... more Near-infrared spectroscopy (NIR) has been used to analyse alunites of formula K(Al3+)6(SO4)4(OH)12. Whilst the spectra of the alunites shows a common pattern differences in the spectra are observed which enable the minerals to be distinguished. These differences are attributed to subtle variations in alunite composition. The NIR bands in the 6300-7000 cm(-1) region are attributed to the first fundamental overtone of both the infrared and Raman hydroxyl stretching vibrations. A set of bands are observed in the 4700-5500 cm(-1) region which are assigned to combination bands of the hydroxyl stretching and deformation vibrations. NIR spectroscopy has the ability to distinguish between the alunite minerals even when the formula of the minerals is closely related. The NIR spectroscopic technique has great potential as a mineral exploratory tool on planets and in particular Mars.

Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2007

The ability of near infrared reflectance spectroscopy to classify the rosasite group minerals fro... more The ability of near infrared reflectance spectroscopy to classify the rosasite group minerals from spectral characteristics is demonstrated. NIR spectroscopy can be regarded as an alternative tool for structure analysis. The spectra show that rosasite group minerals with different cations can be distinguished. Ni2+ in nullaginite [Ni2(CO3)(OH)2] is conspicuous through a single broad band absorption feature at 8525 cm-1, extended from 11,000 to 7000 cm-1. The effect of Ni on Cu is seen in the spectrum of glaukosphaerite [(Cu, Ni)2(CO3)(OH)2] both by a red shift of the spectrum and reduction in intensity of bands with variable positions of band maxima for Cu2+ at 6995 cm-1 and Ni2+ at 7865 cm-1. The spectrum of rosasite [(Cu, Zn)2(CO)3(OH)2] is characterised by Cu2+ band at 7535 cm-1. Kolwezite [(Cu, Co)2(CO)3(OH)2] is a spectral mixture of Cu and Co but optically separated by Co2+ and Cu2+ peaks at 8385 and 7520 cm-1. Vibrational spectra of carbonates show a number of bands in the 7000-4000 cm-1 region attributable to overtones, combination of OH stretching and deformation modes. They appear to be uniform in nature since the structure of rosasite group minerals is identical. The complexity of these features varies between samples because of the variation in composition and hence is useful for discriminating different hydrous carbonates.

Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2007

Minerals in the rosasite group namely rosasite, glaucosphaerite, kolwezite, mcguinnessite have be... more Minerals in the rosasite group namely rosasite, glaucosphaerite, kolwezite, mcguinnessite have been studied by a combination of infrared and Raman spectroscopy. The spectral patterns for the minerals rosasite, glaucosphaerite, kolwezite and mcguinnessite are similar to that of malachite implying the molecular structure is similar to malachite. A comparison is made with the spectrum of malachite. The rosasite mineral group is characterised by two OH stretching vibrations at approximately 3401 and 3311 cm-1. Two intense bands observed at approximately 1096 and 1046 cm-1 are assigned to nu1(CO3)2- symmetric stretching vibration and the delta OH deformation mode. Multiple bands are found in the 800-900 and 650-750 cm-1 regions attributed to the nu2 and nu4 bending modes confirming the symmetry reduction of the carbonate anion in the rosasite mineral group as C2v or Cs. A band at approximately 560 cm-1 is assigned to a CuO stretching mode.

Polyhedron, 2007

Minerals in the rosasite mineral group namely rosasite, glaucosphaerite, kolwezite, mcguinnessite... more Minerals in the rosasite mineral group namely rosasite, glaucosphaerite, kolwezite, mcguinnessite have been studied by powder X-ray diffraction, scanning electron microscopy and infrared spectroscopy. X-ray diffraction shows the minerals to be complex mixtures with more than one rosasite mineral observed in each sample. SEM analysis shows the minerals to be fibrous in nature and the use of EDAX enabled the chemical composition of the minerals to be determined. The spectral patterns for the minerals rosasite, glaucosphaerite, kolwezite and mcguinnessite are similar to that of malachite implying the molecular structure is similar to malachite. A comparison is made with the spectrum of malachite. The rosasite mineral group is characterised by two OH stretching vibrations at 3401and3311cmAˋ1.Twointensebandsobservedat3401 and 3311 cm À1 . Two intense bands observed at 3401and3311cmAˋ1.Twointensebandsobservedat1096 and 1046 cm À1 are assigned to m 1 (CO 3 ) 2À symmetric stretching vibration and the d OH deformation mode. Multiple bands are found in the 800-900 and 650-750 cm À1 regions attributed to the m 2 and m 4 bending modes confirming the symmetry reduction of the carbonate anion in the rosasite mineral group as C 2v or C s . A band at $560 cm À1 is assigned to a CuO stretching mode.

Journal of Thermal Analysis and Calorimetry, 2008

Thermogravimetric and differential thermogravimetric analysis has been used to characterize aluni... more Thermogravimetric and differential thermogravimetric analysis has been used to characterize alunite of formula [K 2 (Al 3+ ) 6 (SO 4 ) 4 (OH) 12 ]. Thermal decomposition occurs in a series of steps (a) dehydration up to 225°C, (b) well defined dehydroxylation at 520°C and desulphation which takes place as a series of steps at 649, 685 and 744°C.

Journal of Raman Spectroscopy, 2008

Raman spectroscopy at both 298 and 77 K has been used to study a series of selected natural smith... more Raman spectroscopy at both 298 and 77 K has been used to study a series of selected natural smithsonites from different origins. An intense sharp band at 1092 cm −1 is assigned to the CO 3 2− symmetric stretching vibration. Impurities of hydrozincite are identified by a band around 1060 cm −1 . An additional band at 1088 cm −1 which is observed in the 298 K spectra but not in the 77 K spectra is attributed to a CO 3 2− hot band. Raman spectra of smithsonite show a single band in the 1405-1409 cm −1 range assigned to the n 3 (CO 3 ) 2− antisymmetric stretching mode. The observation of additional bands for the n 3 g modes for some smithsonites is significant in that it shows distortion of the ZnO 6 octahedron. No n 2 bending modes are observed for smithsonite. A single band at 730 cm −1 is assigned to the n 4 in phase bending mode. Multiple bands be attributed to the structural distortion are observed for the carbonate n 4 in phase bending modes in the Raman spectrum of hydrozincite with bands at 733, 707 and 636 cm −1 . An intense band at 304 cm −1 is attributed to the ZnO symmetric stretching vibration.

Journal of Near Infrared Spectroscopy, 2006

A suite of sulphate effl orescent minerals from the El Jaroso ravine, Sierra Almagrera, Spain hav... more A suite of sulphate effl orescent minerals from the El Jaroso ravine, Sierra Almagrera, Spain have been analysed by ultraviolet, visible, NIR and mid infrared (IR) spectroscopy. Such a suite of minerals may be used to model the types of mineral deposits on Mars. The minerals were analysed by scanning electron microscopy and X-ray microanalysis (EDX) before spectroscopic analysis. Halotrichite was observed and the EDX analyses showed the mineral to be a mixture of heinrichite and pickingerite. The NIR spectrum of the efl orescencia sample showed the sulphate deposit to be composed of a mixture of jarosite and halotrichites. The 7400 to 6400 cm -1 (1351 to 1562 nm) NIR spectral region of the effl orescent sulphate minerals can be used to characterise the various sulphate deposits. The detection of a band at 8338 cm -1 (1199 nm) reveals the presence of ferrous iron in jarosite which is unusual for the jarosite minerals. This can be caused by ferric iron reduction by thermophilic iron-oxidising bacteria. Mid IR spectra showed the characteristic OH stretching bands of the jarosites and the effl orescent mixtures. The position of water stretching vibrations at 2900 cm -1 and lower shows strong hydrogen bonding as is also evidenced by water bending modes at around 1682 cm -1 .

Journal of Near Infrared Spectroscopy, 2008

The importance of NIR spectroscopy has been successfully demonstrated in the present study of smi... more The importance of NIR spectroscopy has been successfully demonstrated in the present study of smithsonite minerals. The fundamental observations in the NIR spectra, in addition to the anions of OH-and CO32-are Fe and Cu in terms of cation content. These ions ...

Journal of Magnetism and Magnetic Materials, 2013

Spectrochimica Acta Part A-molecular and Biomolecular Spectroscopy, 2008

The mineral nesquehonite Mg(OH)(HCO 3 )·2H 2 O has been analysed by a combination of infrared (IR... more The mineral nesquehonite Mg(OH)(HCO 3 )·2H 2 O has been analysed by a combination of infrared (IR) and infrared emission spectroscopy (IES). Both techniques show OH vibrations, both stretching and deformation modes. IES proves the OH units are stable up to 450 • C. The strong IR band at 934 cm −1 is evidence for MgOH deformation modes supporting the concept of HCO 3 − units in the molecular structure. Infrared bands at 1027, 1052 and 1098 cm −1 are attributed to the symmetric stretching modes of HCO 3 − and CO 3 2− units. Infrared bands at 1419, 1439, 1511, and 1528 cm −1 are assigned to the antisymmetric stretching modes of CO 3 2− and HCO 3 − units. IES supported by thermoanalytical results defines the thermal stability of nesquehonite. IES defines the changes in the molecular structure of nesquehonite with temperature. The results of IR and IES supports the concept that the formula of nesquehonite is better defined as Mg(OH)(HCO 3 )·2H 2 O.

Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2011

The mineral nesquehonite Mg(OH)(HCO 3 )·2H 2 O has been analysed by a combination of infrared (IR... more The mineral nesquehonite Mg(OH)(HCO 3 )·2H 2 O has been analysed by a combination of infrared (IR) and infrared emission spectroscopy (IES). Both techniques show OH vibrations, both stretching and deformation modes. IES proves the OH units are stable up to 450 • C. The strong IR band at 934 cm −1 is evidence for MgOH deformation modes supporting the concept of HCO 3 − units in the molecular structure. Infrared bands at 1027, 1052 and 1098 cm −1 are attributed to the symmetric stretching modes of HCO 3 − and CO 3 2− units. Infrared bands at 1419, 1439, 1511, and 1528 cm −1 are assigned to the antisymmetric stretching modes of CO 3 2− and HCO 3 − units. IES supported by thermoanalytical results defines the thermal stability of nesquehonite. IES defines the changes in the molecular structure of nesquehonite with temperature. The results of IR and IES supports the concept that the formula of nesquehonite is better defined as Mg(OH)(HCO 3 )·2H 2 O.