Mineralogical Magazine最新文献

{"title":"Mineralogical, geochemical, spectroscopic and isotopic investigation of hydrothermal chalcedony in Qazdez-Bahamarz District, Sarbisheh City, Eastern Iran","authors":"Ali Asadi, Mohammad Reza Hosseinzadeh, Vartan Simmonds, Yuanming Pan, Matthew I. Leybourne","doi":"10.1180/mgm.2025.10115","DOIUrl":"https://doi.org/10.1180/mgm.2025.10115","url":null,"abstract":"Abstract Chalcedony forms across a wide area in eastern Iran, particularly in the Sarbisheh district near Birjand city, with notable occurrences in the Qazdez-Bahamarz region. Here, cryptocrystalline quartz is found in hydrothermal veins and veinlets within volcanic rocks hosted by carbonate and intermediate igneous formations. Chalcedony samples of various colours—black, purple, green, blue, lavender, grey, lemon yellow and white—were analysed using diverse techniques. These chalcedony samples display fibrous and granular textures, comprising microcrystalline quartz, cryptocrystalline moganite, and opal-CT and opal-C interlayers. Elements that affect the colouration of chalcedony include iron (producing red and yellow tones), chromium (green), manganese (black, blue and grey patterns), nickel (purple) and copper (also purple). Altered carbonate host rocks are enriched in Fe, Cu, Zn and Cd, with Al and Mn depletion. Stable isotope analyses show δ 18 O values in agates range from +14.9‰ to +25.5‰, whereas δ 18 O and δ 13 C values in carbonate minerals and chalcedony range from +14.1‰ to +24.8‰ and –5.7‰ to +0.7‰, indicating agate formation from mantle-derived hydrothermal fluids mixed with meteoric waters. Raman spectroscopy detected moganite, α-quartz, goethite, aragonite and illite in agate interlayers. Analyses by field-emission scanning electron microscopy (FE-SEM) and energy dispersive X-ray spectroscopy (EDS) revealed minerals of Fe, Cr, Ni, Ti and Sn. X-ray diffraction confirmed chalcedony, moganite and opal-CT, whereas EPR spectroscopy showed strong magnetic backgrounds from goethite and silicon-vacancy centres formed by radioactive decay of U, Th and their byproducts.","PeriodicalId":18618,"journal":{"name":"Mineralogical Magazine","volume":"1 1","pages":"1-19"},"PeriodicalIF":0.0,"publicationDate":"2025-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.cambridge.org/core/services/aop-cambridge-core/content/view/F914387259F6E0F887C0946846C2783C/S0026461X25101151a.pdf/div-class-title-mineralogical-geochemical-spectroscopic-and-isotopic-investigation-of-hydrothermal-chalcedony-in-qazdez-bahamarz-district-sarbisheh-city-eastern-iran-div.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147888586","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mechanisms and factors influencing the removal/recovery of gold nanoparticles by thermally modified pyrite","authors":"YuHong Fu, Shanshan Zhang, Qin Liu, Shanshan Li, Shuai Zhang, Sen Li, Can Wu, Meimei Ran","doi":"10.1180/mgm.2024.101","DOIUrl":"https://doi.org/10.1180/mgm.2024.101","url":null,"abstract":"Abstract The environmental effects of nanoparticles have attracted widespread attention. The removal and recycling of nanoparticles are crucial for both environmental protection and resource reuse. However, current removal and recycling methods are not yet mature, and there is a need to explore inexpensive materials for the efficient removal and recycling of nanoparticles. This study investigates the effects of pyrite species, thermal modification temperature, pH and ionic strength on the adsorption of gold nanoparticles (AuNPs) by pyrite. The experimental results demonstrate that the adsorption rate of artificially thermally modified pyrite is slightly faster than that of naturally thermally modified pyrite. However, the concentration of Fe ions dissolved from the artificially thermally modified pyrite is higher. Natural pyrite, when thermally modified at 400°C and 500°C, adsorbs 100% of AuNPs within 10 min. The lower the acidity of the system, the faster the adsorption rate. Conversely, an increase in ionic strength decreases the adsorption rate. Artificially thermally modified pyrite primarily adsorbs AuNPs through electrostatic gravitational attraction, which is supplemented by a significant amount of chemisorption. After four recycling cycles, the adsorption and desorption rates of AuNPs using artificially thermally modified pyrite were 92.1% and 94.2%, respectively, indicating excellent adsorption and recovery performance. The results of this study provide a new method for the recycling of nanoparticles and an experimental basis for the further application of thermally modified pyrite in environmental treatments.","PeriodicalId":18618,"journal":{"name":"Mineralogical Magazine","volume":"89 1","pages":"56-70"},"PeriodicalIF":0.0,"publicationDate":"2024-12-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147905737","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Efficient conversion of montmorillonite-derived porous nano-silica to nano-silicon for lithium-ion battery anodes","authors":"Jing Du, Jieyang Xie, Shoushu Wei, Tao Xiong, Shiya He, Haiming Huang, Qingze Chen, Runliang Zhu, Jianxi Zhu","doi":"10.1180/mgm.2024.64","DOIUrl":"https://doi.org/10.1180/mgm.2024.64","url":null,"abstract":"Abstract Nano-silicon has been regarded as the most promising anode material for next-generation lithium-ion batteries (LIBs). However, the preparation of nano-silicon suffers from high cost, complex procedures, and low yield, which hinders its commercial application. In this study, porous nano-silicon with particle sizes in the range of 50–100 nm was prepared through molten salt-assisted magnesiothermic reduction using porous nano-silica derived from clay minerals as the precursor. Through combining ball milling and acid activation, the synthesised nano-silica derived from montmorillonite exhibited smaller particle sizes (below 50 nm), higher specific surface area (647 m 2 g –1 ), and total pore volume (0.71 cm 3 g –1 ). This unique structure greatly facilitated the conversion efficiency of silica into nano-silicon by maximising the contact area between silica and magnesium powder and optimising the diffusion kinetics of magnesium atoms. When used as anodes in LIBs, the synthesised nano-silicon materials demonstrated a high specific capacity of up to 1222 mAh g –1 and an excellent capacity retention rate of 79% after 150 cycles at a current density of 0.5 A g –1 . This method provides a novel approach for the cost-effective and large-scale production of nano-silicon materials for high-performance anodes.","PeriodicalId":18618,"journal":{"name":"Mineralogical Magazine","volume":"89 1","pages":"25-35"},"PeriodicalIF":0.0,"publicationDate":"2024-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.cambridge.org/core/services/aop-cambridge-core/content/view/CF669C4632A1BF0233E267C2640DA5AE/S0026461X24000641a.pdf/div-class-title-efficient-conversion-of-montmorillonite-derived-porous-nano-silica-to-nano-silicon-for-lithium-ion-batteries-anode-div.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147899597","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Composition and paragenesis of daqingshanite from the Kamthai carbothermalite, Rajasthan, India","authors":"Roger H. Mitchell","doi":"10.1180/mgm.2024.18","DOIUrl":"https://doi.org/10.1180/mgm.2024.18","url":null,"abstract":"<p>Daqingshanite in the Kamthai REE deposit (India) occurs as two paragenetic types: primary granular coarse grained crystals coexisting with primary carbocernaite, baryte and bastnäsite; and as aligned micro-ovoid globules within clasts of Sr-bearing calcite. Carbocernaite forming trellis-type lamellae in some of these calcite clasts do not represent exsolution and are considered as replacement textures as they formed subsequent to daqingshanite. The origins of the textural relations of the microglobules of daqingshanite to their host Sr-calcite cannot be unambiguously determined, although an exsolution origin is not considered feasible. The textures are similar to those of ‘chalcopyrite disease’ and as such could be interpreted as replacement features formed in a low temperature carbothermal environment which should facilitate replacement. Given that daqingshanite is an early crystallising phase it is also possible that cotectic crystallisation with Sr-calcite occurred, followed by subsolidus re-equilibration with recrystallisation along specific crystallographic planes in the calcite. The Kamthai REE deposit is best described as a low temperature carbothermalite microbreccia consisting of a wide variety of clasts resulting from the autobrecciation of rocks formed during, and after, the magmatic to carbothermal transition of an undetermined parental calcite carbonatite-forming magma. Many clasts have been replaced by late stage La-enriched carbothermal fluids mixed with exogenous water during the final low-temperature stage of evolution of the deposit.</p>","PeriodicalId":18618,"journal":{"name":"Mineralogical Magazine","volume":"3 1","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142177558","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The crystal structure of charmarite – the first case of a 11 × 11 Å superstructure mesh in layered double hydroxides","authors":"Elena S. Zhitova, Andrey A. Zolotarev, Anatoly V. Kasatkin, Rezeda M. Sheveleva, Sergey V. Krivovichev, Igor V. Pekov, Vladimir N. Bocharov","doi":"10.1180/mgm.2024.11","DOIUrl":"https://doi.org/10.1180/mgm.2024.11","url":null,"abstract":"<p>Charmarite, Mn<span>4</span>Al<span>2</span>(OH)<span>12</span>CO<span>3</span>⋅3H<span>2</span>O, is a hydrotalcite supergroup member (or layered double hydroxide, LDH) with a previously unknown crystal structure and a Mn<span>2+</span>-analogue of quintinite (commonly erroneously reported as ‘2:1 hydrotalcite’). The single-crystal X-ray diffraction (XRD) data were obtained from the specimen from Mont Saint-Hilaire, Québec, Canada and are best processed in the space group <span>P</span><span><span><span data-mathjax-type=\"texmath\"><span>$bar{3}$</span></span><img data-mimesubtype=\"png\" data-type=\"\" src=\"https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20240412100051135-0894:S0026461X24000112:S0026461X24000112_inline1.png\"/></span></span>, <span>a</span> = 10.9630(4), <span>c</span> = 15.0732(5) Å and <span>V</span> = 1568.89(12) Å<span>3</span>. The crystal structure has been solved by direct methods and refined to <span>R</span><span>1</span> = 0.0750 for 3801 unique reflections with <span>F</span><span>o</span> &gt; 2σ(<span>F</span><span>o</span>). The charmarite structure has long-range periodicity in the <span>xy</span> plane due to <span><span><span data-mathjax-type=\"texmath\"><span>$2sqrt 3$</span></span><img data-mimesubtype=\"png\" data-type=\"\" src=\"https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20240412100051135-0894:S0026461X24000112:S0026461X24000112_inline2.png\"/></span></span><span>a</span>’ × <span><span><span data-mathjax-type=\"texmath\"><span>$2sqrt 3$</span></span><img data-mimesubtype=\"png\" data-type=\"\" src=\"https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20240412100051135-0894:S0026461X24000112:S0026461X24000112_inline3.png\"/></span></span><span>a</span>’ scheme (or 11 × 11 Å) determined for LDHs for the first time (where <span>a</span>’ is a subcell parameter ≈ 3.2 Å). This periodicity is produced by the combination of two superstructures formed by: (1) Mn<span>2+</span> and Al<span>3+</span> ordering in the metal-hydroxide layers [Mn<span>4</span>Al<span>2</span>(OH)<span>12</span>]<span>2+</span> according to the <span><span><span data-mathjax-type=\"texmath\"><span>$sqrt 3$</span></span><img data-mimesubtype=\"png\" data-type=\"\" src=\"https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20240412100051135-0894:S0026461X24000112:S0026461X24000112_inline4.png\"/></span></span><span>a</span>’ × <span><span><span data-mathjax-type=\"texmath\"><span>$sqrt 3$</span></span><img data-mimesubtype=\"png\" data-type=\"\" src=\"https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20240412100051135-0894:S0026461X24000112:S0026461X24000112_inline5.png\"/></span></span><span>a</span>’ pattern and (2) the (CO<span>3</span>)<span>2–</span> ordering according to the 2<span>a</span>’ × 2<span>a</span>’ pattern in the [CO<span>3</span>(H<span>2</span>O)<span>3</span>]<span>2–</span> interlayer sheet in order to avoid close contacts b","PeriodicalId":18618,"journal":{"name":"Mineralogical Magazine","volume":"31 1","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-03-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140575965","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Ebnerite and epiebnerite: NH4ZnPO4 dimorphs with zeolite-type frameworks from the Rowley mine, Arizona, USA","authors":"Anthony R. Kampf, Xiangping Gu, Hexiong Yang, Chi Ma, Joe Marty","doi":"10.1180/mgm.2024.15","DOIUrl":"https://doi.org/10.1180/mgm.2024.15","url":null,"abstract":"<p>Ebnerite and epiebnerite, both with the ideal formula NH<span>4</span>ZnPO<span>4</span>, are new mineral species from the Rowley mine, Maricopa County, Arizona, USA. They occur in an unusual bat-guano-related, post-mining assemblage of phases. Epiebnerite grows epitactically on ebnerite and replaces it. Ebnerite and epiebnerite are found in intimate association with alunite, halite, mimetite, newberyite, sampleite, struvite and wulfenite on hematite-rich quartz–baryte matrix. Crystals of ebnerite are colourless narrow prisms up to ~0.3 mm in length. The streak is white, lustre is vitreous, Mohs hardness is ~2, tenacity is brittle and fracture is splintery. The density is 2.78(2) g⋅cm<span>–3</span>. Ebnerite is optically uniaxial (–) with ω = 1.585(2) and ɛ = 1.575(2). Epiebnerite occurs as colourless prisms or blades, up to about 10 × 3 × 2 μm, in parallel growth forming ribs with serrated edges epitactic on ebnerite prisms. The streak is white, lustre is vitreous, Mohs hardness is probably ~2, tenacity is brittle. The calculated density is 2.851 g⋅cm<span>–3</span>. Epiebnerite is optically biaxial with all indices of refraction near 1.580. Electron microprobe analysis gave the empirical formula [(NH<span>4</span>)<span>0.89</span>K<span>0.06</span>]<span>Σ0.95</span>(Zn<span>0.96</span>Cu<span>0.07</span>)<span>Σ1.03</span>[(P<span>0.97</span>Si<span>0.03</span>)<span>Σ1.00</span>O<span>4</span>] for ebnerite and [(NH<span>4</span>)<span>0.67</span>K<span>0.28</span>]<span>Σ0.95</span>(Zn<span>0.99</span>Cu<span>0.02</span>)<span>Σ1.02</span>(P<span>1.00</span>O<span>4</span>) for epiebnerite. Ebnerite is hexagonal, <span>P</span>6<span>3</span>, with <span>a</span> = 10.67051(16), <span>c</span> = 8.7140(2) Å, <span>V</span> = 859.25(3) Å<span>3</span> and <span>Z</span> = 8. Epiebnerite is monoclinic, <span>P</span>2<span>1</span>, with <span>a</span> = 8.796(16), <span>b</span> = 5.457(16), <span>c</span> = 8.960(16) Å, β = 90.34(6)°, <span>V</span> = 430.1(17) Å<span>3</span> and <span>Z</span> = 4. The structures of ebnerite (<span>R</span><span>1</span> = 0.0372 for 1168 <span>I</span><span>o</span> &gt; 2σ<span>I</span> reflections) and epiebnerite (known from synthetic monoclinic NH<span>4</span>ZnPO<span>4</span>) are zeolite-like frameworks based upon corner-sharing linkages between alternating ZnO<span>4</span> and PO<span>4</span> tetrahedra with channels in the frameworks hosting the NH<span>4</span> groups. The two structures are topologically distinct. Ebnerite belongs to the family of ‘stuffed derivatives’ of tridymite, whereas epiebnerite possesses an ABW-type zeolite structure.</p>","PeriodicalId":18618,"journal":{"name":"Mineralogical Magazine","volume":"38 1","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-03-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141063109","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Immobilisation of chromium in magnesium carbonate minerals","authors":"Alicja M. Lacinska, Keith Bateman, Simon Chenery, Simon J Kemp, Thomas Liddy, Jeremy C Rushton, Dipankar Saha, Sven L.M. Schroeder","doi":"10.1180/mgm.2023.91","DOIUrl":"https://doi.org/10.1180/mgm.2023.91","url":null,"abstract":"<p>Hexavalent chromium (Cr<span>6+</span>) is a toxic carcinogenic pollutant that might be released by the mining and processing of ultramafic rocks and nickel laterites and which requires permanent removal from the contaminated biosphere. Ultramafic material can also serve as a feedstock for the sequestration of CO<span>2</span> resulting from the growth of new minerals, raising the intriguing proposition of integrated sequestration of both pollutants, CO<span>2</span> and chromium, into magnesium carbonates. Such a synergistic process downstream of ore recovery and mineral processing could be an elegant proposition for more sustainable utilisation and management of the Earth's resources. We have therefore carried out an experimental and microanalytical study to investigate potentially suitable carbonate minerals. Uptake of chromium in carbonate phases was determined, followed by identification of the crystalline phases and characterisation of the local structural environment around the incorporated chromium centres. The results suggest that neither nesquehonite nor hydromagnesite have the structural capacity to incorporate Cr<span>6+</span> or Cr<span>3+</span> significantly at room temperature. We therefore propose that further research into this technology should focus on laboratory assessments of other phases, such as layered double hyroxides, that have a natural structural capacity to uptake both chromium and CO<span>2</span>.</p>","PeriodicalId":18618,"journal":{"name":"Mineralogical Magazine","volume":"24 1","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140045699","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Similarities and differences among selected gemmological varieties of chalcedony: chemistry, mineralogy and microstructure","authors":"Sara Monico, Marco Cantaluppi, Valeria Diella, G. Diego Gatta, Ilaria Adamo, Patrizia Fumagalli, Nicoletta Marinoni","doi":"10.1180/mgm.2023.92","DOIUrl":"https://doi.org/10.1180/mgm.2023.92","url":null,"abstract":"<p>This study describes a new variety of chalcedony with a unique inhomogeneous bluish green hue, named aquaprase. It was discovered in Africa and is considered to be a valuable addition to the gem trade. A multi-methodological approach was used to examine its chemistry, mineralogy and microstructure, which were then compared to those of chrysoprase and agate, two of the most popular varieties of chalcedony. Optical microscopy revealed a complex microstructural heterogeneity in the different colour intensity areas/bands of aquaprase and agate, whereas chrysoprase exhibited a more homogeneous coexistence of micro- and cryptocrystalline quartz. High-resolution synchrotron XRD was essential for highlighting the complex assemblage of various types of α-quartz in aquaprase and agate (which differ in terms of crystal size and/or cell parameters). Micro-Raman spectroscopy revealed α-quartz and moganite in all three varieties of chalcedony and the presence of the nickel-bearing layered silicate mineral, willemseite, in chrysoprase, which is responsible for its green colouration. The chemical analysis displayed a homogeneous composition of agate, as well as high levels of nickel content in the chrysoprase variety. Aquaprase showed significant amounts (ppm by weight) of trace elements (Al, Mg, Na, K, Ca, Ti, U and Fe) characteristic of its formation environment, as well as high values of Cr, which are thought to be the cause of its bluish green colouration.</p>","PeriodicalId":18618,"journal":{"name":"Mineralogical Magazine","volume":"26 1","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-02-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139771419","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Is tapering or discontinuation of biologic treatment in patients with radiographic and nonradiographic axial spondyloarthritis reasonable? : A local cohort study.","authors":"Halil Harman, Nedim Kaban","doi":"10.1007/s00393-022-01226-0","DOIUrl":"10.1007/s00393-022-01226-0","url":null,"abstract":"<p><strong>Objective: </strong>We retrospectively determined factors predicting biologic treatment discontinuation or tapering in patients with axSpA.</p><p><strong>Materials and methods: </strong>We included 63 nonradiographic axSpA (nr-axSpA) and 138 radiographic axSpA (r-axSpA) patients on biologic treatments for at least 1 year. The biologic dosing intervals were increased in patients who had been in remission for at least 6 months. In patients whose biologic dosing intervals could be increased by 100% for at least 6 months, the agents were stopped at the end of that time. In patients for whom the biologic agents were stopped or tapered, relapse was defined as a Bath Ankylosing Spondylitis Disease activity index score > 4 and a CRP level > 10 mg/L.</p><p><strong>Results: </strong>The median duration of biologic treatment (all patients) was 2 (1-11) years. Logistic regression analysis did not identify any independent predictor of treatment discontinuation. NSAID use was the only independent predictor of tapering (p = 0.001). The time to relapse after tapering was shorter in patients with r‑axSpA than nr-axSpA (25.97 vs. 39.53 months; p = 0.05). The time to relapse in patients with r‑axSpA was considerably shorter than that in patients with nr-axSpA (5.14 vs. 13 months; p = 0.001). All r‑axSpA patients relapsed over the follow-up period; only 2 nr-axSpA patients did not relapse.</p><p><strong>Conclusion: </strong>The most significant independent predictor of relapse was NSAID use during treatment. For axSpA patients in remission, tapering of the biologic dosing intervals is more appropriate than discontinuation.</p>","PeriodicalId":18618,"journal":{"name":"Mineralogical Magazine","volume":"1 1","pages":"55-61"},"PeriodicalIF":0.0,"publicationDate":"2024-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87911809","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Dmitryvarlamovite, Ti2(Fe3+Nb)O8, a new columbite-supergroup mineral related to the wolframite group","authors":"Oksana V. Udoratina, Taras L. Panikorovskii, Nikita V. Chukanov, Mikhail V. Voronin, Vladimir P. Lutoev, Atali A. Agakhanov, Sergey I. Isaenko","doi":"10.1180/mgm.2023.95","DOIUrl":"https://doi.org/10.1180/mgm.2023.95","url":null,"abstract":"<p>The new columbite-supergroup mineral dmitryvarlamovite, ideally Ti<span>2</span>(Fe<span>3+</span>Nb)O<span>8</span>, was discovered in weathered alkaline metasomatic assemblages formed after late Riphaean sedimentary carbonate rocks of the Verkhne-Shchugorskoe deposit, Middle Timan Mts., Russia. The associated minerals are columbite-(Fe), pyrochlore-group minerals, monazite-(Ce), xenotime-(Y), baryte, pyrite, drugmanite and plumbogummite. Dmitryvarlamovite occurs as isolated anhedral equant grains up to 0.5 mm across. The colour of dmitryvarlamovite is black, the streak is black and the lustre is submetallic. The new mineral is brittle, with the mean VHN hardness of 753 kg mm<span>–2</span> corresponding to the Mohs’ hardness of 6. No cleavage is observed. The fracture is conchoidal. The calculated density is 4.891 g⋅cm<span>–3</span>. In reflected light, dmitryvarlamovite is light grey; no pleochroism is observed. The reflectance values (<span>R</span><span>min</span>, % / <span>R</span><span>max</span>, % / λ, nm) are: 19.8/20.3/470, 18.3/18.9/546, 17.8/18.5/589 and 17.3/17.8/650. The chemical composition is (electron microprobe data, with iron divided into Fe<span>2</span>O<span>3</span> and FeO based on the charge balance, wt.%): MnO 0.11, FeO 1.51, V<span>2</span>O<span>3</span> 0.89, Cr<span>2</span>O<span>3</span> 0.28, Fe<span>2</span>O<span>3</span> 19.26, TiO<span>2</span> 37.72, Nb<span>2</span>O<span>5</span> 40.08, total 99.85. The IR and Raman spectra indicate the absence of H-, C- and N-bearing groups. The empirical formula is (Fe<span>2+</span><span>0.08</span>V<span>3+</span><span>0.05</span>Cr<span>3+</span><span>0.01</span>Fe<span>3+</span><span>0.92</span>Ti<span>1.79</span>Nb<span>1.15</span>)<span>Σ4.00</span>O<span>8</span>. The crystal structure was determined using single-crystal X-ray diffraction data and refined to <span>R</span> = 0.048. Dmitryvarlamovite is orthorhombic, space group <span>P</span>2<span>1</span>2<span>1</span>2, <span>a</span> = 4.9825(6), <span>b</span> = 4.6268(4), <span>c</span> = 5.5952(6) Å and <span>V</span> = 5.5952(6) Å<span>3</span> (<span>Z</span> = 1). The structure is related to those of wolframite-group minerals but differs in the scheme of cation ordering. The crystal-chemical formula derived based on the structural data is (Ti<span>0.57</span>Nb<span>0.21</span>Fe<span>3+</span><span>0.15</span>Fe<span>2+</span><span>0.04</span>V<span>0.02</span>Cr<span>0.01</span>)<span>2</span>(Nb<span>0.36</span>Ti<span>0.33</span>Fe<span>3+</span><span>0.31</span>)<span>2</span>O<span>8</span>. The strongest lines of the powder X-ray diffraction pattern [<span>d</span>, Å (<span>I</span>, %) (<span>hkl</span>)] are: 3.58 (40) (011), 2.911 (100) (111), 2.809 (40) (002), 2.497 (38) (020), 2.447 (29) (103), 1.7363 (32) (103) and 1.7047 (29) (220). Dmitryvarlamovite is named after Dmitry Anatol'evich Varlamov (b. 1965).</p>","PeriodicalId":18618,"journal":{"name":"Mineralogical Magazine","volume":"97 1","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139771176","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}