Canadian Mineralogist最新文献

{"title":"Phosphate mineral associations from the Tres Arroyos aplite-pegmatites (Badajoz, Spain): Petrography, mineral chemistry, and petrogenetic implications","authors":"I. Garate-Olave, E. Roda-Robles, P. Gil-Crespo, A. Pesquera","doi":"10.3749/CANMIN.1900102","DOIUrl":"https://doi.org/10.3749/CANMIN.1900102","url":null,"abstract":"In the Tres Arroyos granite-pegmatite system (Badajoz, Spain) a zoned aplite-pegmatite field occurs, with poorly evolved, intermediate, and Li-rich dikes intruded into metasediments, close to the contact with the Nisa-Alburquerque granitic batholith. A large variety of Fe-Mn phosphate minerals occur in the poorly evolved aplite-pegmatites; Al-phosphates occur mainly in the intermediate and Li-rich dikes. The Fe/(Fe + Mn) ratio of the Fe-Mn phosphates is the highest reported for aplite-pegmatite fields in the Central Iberian Zone, suggesting a low degree of fractionation for the poorly evolved aplite-pegmatites that host these minerals. In contrast, the high F contents observed in crystals of the amblygonite–montebrasite series from the intermediate and Li-rich aplite-pegmatites indicates a higher fractionation degree for these dikes. The relatively common occurrence of phosphate minerals in the three types of aplite-pegmatites from Tres Arroyos attests to a significant availability of P in the pegmatitic melt. In this granite pegmatite system, P first started behaving as a compatible element, thus favoring the crystallization of discrete phosphates, during the crystallization of the poorly evolved aplite-pegmatites. In more fractionated melts, where Fe-Mn-(Mg) contents were extremely depleted, P was still available, allowing the crystallization of the Al-phosphates, mainly of the amblygonite–montebrasite series, in the more evolved intermediate and Li-rich aplite-pegmatites. Subsolidus replacement of the early phosphate phases, such as those of the amblygonite–montebrasite series, by lacroixite, together with the presence of late Ca- and Sr-bearing phosphates such as jahnsite-(CaMnFe), whiteite-(CaFeMg), mitridatite, and goyazite, attest to a high activity of metasomatic fluids in the Tres Arroyos granite-pegmatite system. Consequently, variations in the phosphate mineral associations and in their chemical compositions reflect well the fractional crystallization processes suffered by the pegmatitic melts from the poorly evolved up to the Li-rich dikes, as well as the subsolidus history of the Tres Arroyos system.","PeriodicalId":9455,"journal":{"name":"Canadian Mineralogist","volume":" ","pages":""},"PeriodicalIF":0.9,"publicationDate":"2021-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42762235","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Bismuth minerals from the intragranitic La Elsa NYF pegmatite, Potrerillos granite, Argentina: Monitors of fluid evolution from magmatic to hydrothermal stage","authors":"R. Škoda, M. Novak, R. Čopjaková, M. A. Galliski, M. F. Márquez-Zavalía, J. Sejkora","doi":"10.3749/CANMIN.2000011","DOIUrl":"https://doi.org/10.3749/CANMIN.2000011","url":null,"abstract":"\u0000 The NYF La Elsa pegmatite forms a subcircular, ∼30 m long, ∼20 m wide body enclosed in the parental Potrerillos granite, Las Chacras-Potrerillos batholith, Argentina. The pegmatite has a typical zonal internal structure with a volumetrically significant quartz core and pods of magmatic fluorite. Along with biotite, mostly in the outer units, tourmaline (schorl, fluor-schorl) is common to abundant in most pegmatite units. Accessory minerals include common strongly hematitized ilmenite and rare euhedral crystals of bismuthinite, up to 2 cm long, occurring at the transition between the blocky zone and the quartz core. The bismuthinite was significantly replaced by bismutite I according to the reaction Bi2S3(s) + CO2(aq) + 6O2(aq) + 3H2O(l) = Bi2CO3O2(s) + 3H2SO4(aq). Subsequently, bismutite I was replaced by bismutite II and kettnerite. The former requires an influx of Ca and F and its formation can be characterized by the reaction Bi2CO3O2(s) + 2Ca2+(aq) + 2F–(aq) + CO32–(aq) = 2CaBiCO3OF(s). At the late hydrothermal stages bismutite was replaced by clinobisvanite/pucherite during influx of V according to the reaction Bi2CO3O2s + 2H3VO4(aq) = 2BiVO4(s)+ CO2(aq) + 3H2O(l). All Bi minerals are close to the ideal formulae with only minor Pb and ±Cu in bismuthinite and its secondary products. The crystallization sequence of Bi minerals is magmatic bismuthinite (S2–) → early hydrothermal bismutite I (CO32–) → medium stage bismutite II + kettnerite (CO32–, F–) → late stage clinobisvanite, pucherite (VO43–). Pegmatite-derived early subsolidus fluids were enriched in CO2, which was confirmed by confocal Raman microspectroscopy of fluid inclusions in quartz and caused breakdown of bismuthinite to bismutite. Calcium and F, necessary for kettnerite formation, were released during alteration of magmatic fluorite at acidic conditions. Vanadium was supplied by meteoritic H2O enriched in elements from altered magmatic minerals (biotite, ilmenite), either from the pegmatite or from the host granite.","PeriodicalId":9455,"journal":{"name":"Canadian Mineralogist","volume":"58 1","pages":"717-732"},"PeriodicalIF":0.9,"publicationDate":"2021-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47433329","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Beryllium-silicon disorder and rare earth crystal chemistry in gadolinite from the White Cloud pegmatite, Colorado, USA","authors":"J. Allaz, J. Smyth, Rhiana E. Henry, C. Stern, P. Persson, Joy J. Ma, M. Raschke","doi":"10.3749/CANMIN.1900084","DOIUrl":"https://doi.org/10.3749/CANMIN.1900084","url":null,"abstract":"Gadolinite, REE2FeBe2Si2O10, is a monoclinic orthosilicate member of the gadolinite supergroup of minerals and occurs in beryllium and rare earth element (REE) bearing granites, pegmatites, and some metamorphic rocks. Gadolinite from the White Cloud pegmatite, South Platte Pegmatite district, Colorado, USA, has been investigated and shows unusually variable REE compositions and distinct Be-Si disorder. Crystal structure and chemistry of two petrographically distinct gadolinite samples from this locality have been studied by electron microprobe chemical analysis, laser ablation inductively coupled plasma-mass spectrometry (LA-ICP-MS), single-crystal X-ray diffraction (XRD), and micro-Raman spectroscopy. Within these samples, the gadolinite was found to range from gadolinite-(Y) to gadolinite-(Ce). Regions of nearly full occupancy of Fe at the M site, and partial substitution of Si for Be at the Q tetrahedral site, as well as substitution of Be for Si at the T site were observed, with up to 15% vacancy at the Fe site and up to 15% disorder between Be and Si at distinct tetrahedral sites elsewhere. The layered nature of the crystal structure allows for large variation of the radius of the cation at the A site which contains the REE. This study shows that Be may substitute for Si and that Be may be more abundant in geochemical systems than previously assumed.","PeriodicalId":9455,"journal":{"name":"Canadian Mineralogist","volume":" ","pages":""},"PeriodicalIF":0.9,"publicationDate":"2021-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41508105","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Exploration Advancement of the Stewardson Lake Uranium Project (Athabasca Basin, Canada) Using an Integrated Geological and Geochemical Methodology and Academic–Industry Collaboration","authors":"S. Beyer, P. Stewart, L. Lahusen, K. Kyser, L. Bzdel","doi":"10.3749/CANMIN.2000033","DOIUrl":"https://doi.org/10.3749/CANMIN.2000033","url":null,"abstract":"\u0000 Kurt Kyser contributed significantly to understanding the role that fluids play in the formation of unconformity-related U deposits in Canada and Australia and also in the exploration for these deposits. Kurt's exploration research was collaborative with industry, and arguably the most productive of the many industry-collaborative relationships Kurt developed was with Uravan Minerals, a junior exploration company. Ten years of collaborative U-deposit and exploration geochemical research with Uravan, including development of innovative multi-media surface sampling and analytical methods, culminated with the Stewardson Lake uranium exploration project in the Proterozoic Athabasca Basin, Canada. Soil clay separates, pine and spruce tree cores and vegetation, and glacially transported sandstone boulders collected at Stewardson Lake record 207Pb/206Pb ratios as low as 0.18, indicative of radioactive decay of U in a Proterozoic-aged U deposit, and elevated pathfinder elements such as Ni and Co in two areas of the Stewardson Lake property named Areas A and B. Four diamond drill holes in Areas A and B tested targets consisting of anomalous surface-media geochemistry coincident with conductive host rocks determined using geophysical methods. The favorable targeting characteristics were not explained by two of the drill holes in Area A, where only narrow intervals of elevated U, radiogenic Pb, and pathfinder elements or structural disruption that can accompany Athabasca U deposits were intersected. Two drill holes in Area B intersected a broad zone of characteristic chlorite + hematite + illite alteration and U concentrations >1 ppm (aqua regia) in the basal host sandstone. One drill hole in Area B intersected a ∼30-meter-thick hydrothermal alteration zone consisting of silicification, chlorite + kaolinite clay alteration, smoky quartz, Ni-Fe sulfides, and disseminated uraninite accompanied by elevated gamma count rates. Fractures in the host sandstone in Area B record the highest pathfinder concentrations and the most radiogenic Pb isotope ratios and were likely a conduit for secondary dispersion of alteration-related components to the surface. The results validate the Uravan/QFIR exploration model developed over a decade of collaborative applied research and confirm that the Stewardson Lake area is highly prospective to host unconformity-related U mineralization. Lastly, clay alteration mineralogy in the Stewardson Lake area is contrasted with that in the eastern Athabasca Basin, and the value of the industry–academic relationship that benefited both Uravan Minerals and Kurt's Queen's Facility for Isotope Research laboratory is discussed.","PeriodicalId":9455,"journal":{"name":"Canadian Mineralogist","volume":" ","pages":""},"PeriodicalIF":0.9,"publicationDate":"2021-01-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47259806","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Raman and FTIR Spectroscopy of Synthetic Amphiboles: II. Divalent (Mg,Co) Substitutions at the Octahedrally Coordinated Sites","authors":"G. Ventura, B. Mihailova, F. Hawthorne","doi":"10.3749/CANMIN.1900091","DOIUrl":"https://doi.org/10.3749/CANMIN.1900091","url":null,"abstract":"\u0000 Raman spectra were recorded for a set of synthetic amphiboles, Na(NaCa)(Mg5–xCox)Si8O22(OH)2 with x = 0–5, that have been previously characterized by Rietveld structure refinement and infrared spectroscopy in the principal OH-stretching region. The chemical compositions derived from the intensities of the O-H stretching Raman peaks are in accord with the nominal compositions, as well as with the compositions previously determined by both Rietveld structure refinement and infrared spectroscopy. Detailed peak assignments have been made of the Raman spectra in the low-wavenumber region (50–1200 cm–1) starting from the work of Leissner et al. (2015) and Waeselmann et al. (2019) and the simulated partial Raman spectra for all the cation-anion pairs in the structure of potassic-magnesio-arfvedsonite given by Ivanov et al. (2018). Most Raman peaks exhibit one-mode behavior and shift toward lower wavenumbers for increasing Co in the amphibole.","PeriodicalId":9455,"journal":{"name":"Canadian Mineralogist","volume":" ","pages":""},"PeriodicalIF":0.9,"publicationDate":"2021-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41892697","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Demagistrisite, the Missing Link in a Polysomatic Series from Lawsonite to Orientite","authors":"F. Cámara, A. Kampf, F. Nestola, M. Ciriotti, Deborah Spartà, C. Balestra","doi":"10.3749/CANMIN.2000021","DOIUrl":"https://doi.org/10.3749/CANMIN.2000021","url":null,"abstract":"\u0000 Demagistrisite, ideally BaCa2Mn3+4(Si3O10)(Si2O7)(OH)4·3H2O, is a new mineral found at the Cerchiara mine (eastern Liguria, La Spezia province, Italy). The ore consists of rhythmic interlaying of braunite-bearing metasediments (5–15 cm thick) and hematite-rich cherts. Demagistrisite occurs in association with cerchiaraite-(Mn), namansilite, noelbensonite, orientite, richterite, ruizite, and saponite in matrix consisting of braunite, calcite, cryptomelane, orthoclase, and quartz. Demagistrisite crystals occur as tightly intergrown blades or as millimeter-sized prisms and needles with square cross-section, typically with irregular terminations, and rarely terminated by a low-angle pyramid. The mineral is orange brown to red brown, streak is beige, and luster is vitreous, translucent to transparent. Fracture is irregular. In thin section, it is orange brown. The mineral is optically biaxial (–) with α 1.805(5), β 1.825(5), γ 1.8305(5) (white light); 2Vmeas 58(5)°, 2Vcalc 54.7°; optical orientation X = c, Y = b, Z = a. Dispersion is very strong, r > v. Pleochroism is strong with X orange yellow, Y red brown, Z red brown; X << Z < Y. It is unreactive in concentrated HCl at room temperature. Thirteen chemical analyses by WDS-EMPA gave the following empirical formula (based on 24 O apfu): (Ba0.69Ca1.25Mn2+0.70Sr0.21Na0.12Mg0.02)Σ2.99(Mn3+3.97Al0.03)Σ4(Si3O10)(Si2O7)(OH)3.87·3.13H2O. The mineral is orthorhombic, space group Amm2, with unit-cell parameters a 16.312(8), b 6.176(4), c 9.075(6) Å, V 914.2(10) Å3, and Z = 2. The seven strongest X-ray powder diffraction lines are [d Å (I%; hkl)]: 16.21 (49; 100), 4.86 (44; 111), 4.34 (56; 102,211), 2.871 (54; 220), 2.731 (100; 511,013), 2.671 (74; 320,113,502), and 2.426 (51; 222,313,611). The crystal structure (R1 = 0.0572 for 1485 reflections with I > 2σI) is based on straight edge-sharing chains of Mn3+-centered octahedra extending along [010], which are bridged by disilicate (Si2O7) and trisilicate (Si3O10) groups, yielding a framework. Cavities within this framework contain two large cation sites. The structure of demagistrisite can be considered transitional between the structures of orientite and noelbensonite. Demagistrisite is named in honor of Leandro de Magistris (1906–1990).","PeriodicalId":9455,"journal":{"name":"Canadian Mineralogist","volume":"59 1","pages":""},"PeriodicalIF":0.9,"publicationDate":"2021-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48303268","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Chlorine-Rich Amphiboles from the Grenville-Age Hudson Highlands of New York State","authors":"Alexandra J. Gilland, Laurel I. Hebert, Diego R Javier-Jiménez, J. M. Masi, Shannon R. Meyler, Spencer G. Schwartz, E. A. Verhaeg, John M. Hughes, E. Lincoln, G. P. O'Brien, Sarah K. Powers, R. Schireman, M. Lupulescu, D. G. Bailey","doi":"10.3749/CANMIN.2000052","DOIUrl":"https://doi.org/10.3749/CANMIN.2000052","url":null,"abstract":"\u0000 Some Grenville-age rocks exposed in the uplifted region of the Hudson Highlands of southern New York are amphibole-dominant igneous rocks. The amphibole-rich rocks, which are locally pegmatitic in nature, are associated with magnetite ore and coarse-grained syenite; the ore was discovered and mined from the middle of the 18th century to the end of the 19th century. The amphiboles have attracted the attention of many researchers for nearly two centuries. Chemical analyses demonstrate that they are pargasite or hastingsite in composition and are particularly rich in Cl and K. High-precision crystal structure analyses of 11 Cl-rich amphiboles from the Hudson Highlands (0.0134 <R1 < 0.0169), including separation of M(1)Fe and M(1)Mg, allow corroboration of, and greatly extends the range of, previous models of Cl incorporation in amphiboles that were derived from a small number of samples. In addition to crystal structures and major-element analyses, trace-element data and Raman spectra are provided.","PeriodicalId":9455,"journal":{"name":"Canadian Mineralogist","volume":" ","pages":""},"PeriodicalIF":0.9,"publicationDate":"2021-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44144975","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Determination of the Crystal Structure and Redefinition of Tsugaruite, Pb28As15S50Cl, the First Lead-Arsenic Chloro-Sulfosalt","authors":"C. Biagioni, L. Bindi, K. Momma, R. Miyawaki, Y. Matsushita, Yves Më","doi":"10.3749/CANMIN.2000005","DOIUrl":"https://doi.org/10.3749/CANMIN.2000005","url":null,"abstract":"\u0000 Tsugaruite was originally defined as a lead-arsenic sulfosalt from the Yunosawa mine, Aomori Prefecture, Japan. Until recently its crystal structure remained unsolved and its actual classification in the sulfosalt realm was unknown. Here the refinement of the crystal structure of tsugaruite using single-crystal X-ray diffraction data is reported. The mineral is orthorhombic, space group P2nn, with unit-cell parameters a = 8.0774(10), b = 15.1772(16), c = 38.129(4) Å, V = 4674.3(9) Å3, in agreement with previous studies. The solution of the crystal structure of this mineral revealed Cl occupying a specific position. Chlorine was thus sought and found using the electron microprobe; the average of six spot analyses gave (in wt.%): Pb 68.04, As 12.83, S 18.29, Cl 0.63, total 99.80. The empirical formula, calculated on the basis of Pb + As = 43 atoms per formula unit, is Pb28.26As14.74S49.08Cl1.52. Tsugaruite is an N = 4 plesiotypic derivative of the homologous series of Pb-Sb chloro-sulfosalts having the general formula Pb(2+2N)(Sb,Pb)(2+2N)S(2+2N)(S,Cl)(4+2N)ClN. It has a Cl/(Cl + S) atomic ratio close to that of other known Pb-Sb chloro-sulfosalts (pillaite, pellouxite) and slightly higher than that of dadsonite.","PeriodicalId":9455,"journal":{"name":"Canadian Mineralogist","volume":" ","pages":""},"PeriodicalIF":0.9,"publicationDate":"2020-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48187098","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"In situ observations of the transition between beryl and phenakite in aqueous solutions using a hydrothermal diamond-anvil cell","authors":"X. Wang, Jiankang Li","doi":"10.3749/canmin.1900104","DOIUrl":"https://doi.org/10.3749/canmin.1900104","url":null,"abstract":"\u0000 Beryl and phenakite are important industrial beryllium minerals. In the hydrous melt of the BeO–Al2O3–SiO2–H2O (BASH) system, experiments using quench-type high-temperature and high-pressure equipment have revealed that the different activities of Al2O3 and SiO2 (αAl2O3 and αSiO2) are the main factors that lead to different beryllium mineral assemblages. In this study, we attempted in situ observation of the crystallization process of phenakite and beryl in an aqueous solution of the BASH system using a hydrothermal diamond-anvil cell. Experimental results indicate that phenakite and beryl can crystallize faster in this regime (i.e., 2.93–0.58 × 10−5 cm/s in length and 22.39–3.23 μm3/s in volume) than from a hydrous melt. In addition, in the phenakite and beryl crystallization, pressure–temperature conditions were greater than 467 °C and 220 MPa and 495 °C and 221 MPa, respectively, and their upper temperatures and pressures attained 845–870 °C and 500–1300 MPa. These features indicate that temperature is not the main factor that controls the stability of phenakite and beryl in the BASH system. This stability can be attributed to the diffusion of components in aqueous solution that change αSiO2 and αAl2O3 during the heating and cooling processes. During heating, αSiO2 increases while beryl is dissolving, which leads to phenakite crystallization; during cooling, αSiO2 and αAl2O3 are sufficient for the remaining beryl to recrystallize. Therefore, the transition between phenakite and beryl in the aqueous solution in the BASH system may be different during heating and cooling processes. This reasoning can explain the abundance of phenakite in miarolitic cavities and the occurrence of phenakite, rather than beryl, in hydrothermally altered pegmatites, volcanic rocks, and other beryllium-rich rocks.","PeriodicalId":9455,"journal":{"name":"Canadian Mineralogist","volume":" ","pages":""},"PeriodicalIF":0.9,"publicationDate":"2020-12-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45990440","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Raman and FTIR Spectroscopy of Synthetic Amphiboles: I. The OH Librational Bands and the Determination of the OH-F Content of Richterites via Raman Spectroscopy","authors":"G. Ventura, F. Hawthorne, B. Mihailova, A. Sodo","doi":"10.3749/canmin.1900090","DOIUrl":"https://doi.org/10.3749/canmin.1900090","url":null,"abstract":"\u0000 Unpolarized FTIR and Raman spectra were collected in the regions 4000–4600 cm–1 (NIR) and 100–4000 cm–1 from previously synthesized and characterized amphiboles in the systems richterite–fluoro-richterite, potassic-richterite–potassic-fluoro-richterite, rubidium-richterite–rubidium-fluoro-richterite, and potassic-richterite–deuterated potassic-richterite. The NIR spectra of Na-, K-, and Rb-richterites have peaks at 4325, 4210 cm–1, and 3735–3730 cm–1. All three peaks decrease in intensity with increasing F content, indicating that the higher-energy peaks are combination bands involving the principal OH-stretch at 3735–3730 cm–1 and two OH-libration modes, the frequencies of which can be calculated from the relation ωcombination ≈ ωOH + ωlibration; these are 590 and 475 cm–1, respectively. The FTIR spectra of the richterite–fluoro-richterite and potassic-richterite–potassic-fluoro-richterite series show decreasing intensity and eventual disappearance of the band at ∼600 cm–1 with increasing F in accord with the assignment of this band as due to OH-libration. Raman spectra of the potassic-richterite–deuterated potassic-richterite amphiboles in the low-energy region show the disappearance of two peaks at 585 and 473 cm–1 that we have assigned to OH-libration modes. Collectively, these spectroscopic results indicate that there are two OH-libration modes at ∼590 and ∼475 cm–1 in these synthetic richterites and, by implication, in all monoclinic OH-bearing amphiboles with filled A sites. Similarly to FTIR, the relative intensities of the stretching modes associated with OH-A-OH and OH-A-F local configurations in the Raman spectra provide a reliable estimation of the F content in these A site-filled amphiboles.","PeriodicalId":9455,"journal":{"name":"Canadian Mineralogist","volume":" ","pages":""},"PeriodicalIF":0.9,"publicationDate":"2020-12-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42783116","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}