附件2.实验室方法描述.doc

Table of Contents 1 Analytical method of K isotopes.........................................................................2 2 Analytical method of Ca isotopes .......................................................................3 3 Analytical method of Fe isotopes........................................................................4 4 Analytical method of Cu isotopes .......................................................................5 5 Analytical method of Zn isotopes .......................................................................6 6 Analytical methods of Cu-Fe-Zn isotopes ..........................................................7 7 Analytical method of Li isotopes ........................................................................8 8 Analytical procedures of Re-Os dating for metal sulfide....................................9 9 Analytical method for In situ trace element analysis by LA-SF-ICP-MS ........10 1 1 Analytical method of K isotopes Potassium isotopic analyses were conducted at Metallogenic Elements and Isotopes Lab in the Institute of Geology and Geophysics, Chinese Academy of Sciences (IGGCAS), following the protocol described in Li et al. (2022). Approximately 5–20 mg of sample powders were weighed and digested using mixture of concentrated HNO3 and HF. The digested sample solutions were evaporated to dryness and then treated sequentially with aqua regia and 6 mol L-1 HNO3. After evaporating the solutions, the final residues were fully dissolved in 0.5 mol L-1 HNO3 twice prior to column separation. The sample solution was loaded onto preconditioned 2 mL Bio-Rad AG50W-X8 (200-400 mesh) resin and then eluted with a 15 mL of 0.5 mol L-1 HNO3 to remove the matrix elements. The K fraction containing ~ 100% of total K was collected with 20 mL 0.5 mol L-1 HNO3 and then dried down. The same purification process was repeated twice or four times to ensure complete matrix removal. The final K solution was redissolved with 2 % HNO3 ready for measurement. The total procedure blank for K isotope analyses is < 30 ng K, which is negligible compared with tens of μg of K in the solution from sample chemical purification. Potassium isotopic measurements were performed on the Nu Sapphire CC-MC-ICP-MS (Nu Instruments, Wrexham, UK) using the collision cell (lowenergy) path. The hexapole collision cell utilizes He and H2 gas to mostly remove various Ar-based polyatomic species, hence K isotopic ratios can be measured in the low-resolution mode. An auto-sampler SC-2DX (Elemental Scientific, U.S.A.) was connected to an Apex Omega desolvation nebulizer (Elemental Scientific, U.S.A.) system for sample introduction. One Faraday cup is connected to a pre-amplifier fitted with a 1010 Ω resistor for collection of 39K+ ion beam, while the other two Faraday cups using 1011 Ω resistors collect 41K+ and mass 40 beams, respectively. Potassium isotopic data are reported in δ notation relative to SRM 3141a, using the samplestandard bracketing technique for instrumental mass fractionation correction: The K concentration of each sample and standard was matched to within 10% (Li et al., 2023). Each analysis consisted of 1 block of 50 cycles with 4 s integrations. Five to seven repeated analyses were conducted on each sample solution. The longterm (six months) precision, based on multiple measurements of geostandard BCR-2, is ~0.04‰ (2SD; Li et al., 2022). References Li, W.J., Cui, M.M., Pan, Q.Q., Wang, J., Gao, B.Y., Liu, S.K., Yuan, M., Su, B.X., Zhao, Y. and Teng, F.Z. (2022) High-precision potassium isotope analysis using the Nu Sapphire collision cell (CC)-MC-ICP-MS. Science China Earth Sciences 65, 1510-1521. Li, W.J., Zhao, Y., Su, B.X., Gao, B.Y., Wang, J. and Liu, S.K. (2023) Experimental investigation of improved tolerance for concentration mismatch in potassium isotope analysis on a hexapole collision cell MC-ICP-MS (Nu Sapphire). Journal of Analytical Atomic Spectrometry, doi:10.1039/D1033JA00022B. 2 2 Analytical method of Ca isotopes Calcium isotopic analyses were conducted at Metallogenic Elements and Isotopes Lab in the Institute of Geology and Geophysics, Chinese Academy of Sciences (IGGCAS), following the protocol described in Gao et al. (2022). Approximately 20–40 mg of sample powders were weighed and digested using mixture of concentrated HNO3 and HF. The digested sample solutions were evaporated to dryness and then treated sequentially with aqua regia and 6 mol L-1 HNO3. After evaporating the solutions, the final residues were fully dissolved in 2 mol L-1 HCl twice prior to column separation. The sample solution was loaded onto pre-conditioned 2 mL Bio-Rad AG50W-X12 resin (200-400 mesh) resin and then eluted with a 20 mL of 2 mol L-1 HCl to remove the matrix elements. The Ca fraction containing ~ 100% of total Ca was collected with 20 mL 2 mol L-1 HCl and then dried down. The same purification process was repeated twice or four times to ensure complete matrix removal. The final Ca solution was redissolved with 2 % HNO3 ready for measurement. The total procedure blank for Ca isotope analyses is < 80 ng Ca, which is negligible compared with tens of μg of Ca in the solution from sample chemical purification. Calcium isotopic measurements were performed on the Nu Sapphire CC-MC-ICP-MS (Nu Instruments, Wrexham, UK) using the collision cell (low-energy) path. The hexapole collision cell utilizes He and H2 gas to mostly remove various Ar-based polyatomic species, hence Ca isotopic ratios can be measured in the low-resolution mode. An auto-sampler SC-2DX (Elemental Scientific, U.S.A.) was connected to an Apex Omega desolvation nebulizer (Elemental Scientific, U.S.A.) system for sample introduction. One Faraday cup is connected to a preamplifier fitted with a 1010 Ω resistor for collection of 40Ca+ ion beam, while the other five Faraday cups using 1011 Ω resistors collect 42Ca+, 43Ca+, 44Ca+, mass 41 and 43.5 beams, respectively. Calcium isotopic data are reported in δ notation relative to SRM 915a, using the sample-standard bracketing technique for instrumental mass fractionation correction: with x =40, 42, or 43. The radiogenic input on 40Ca is usually noted using the epsilon notation as: The Ca concentration of each sample and standard was matched to within 4%. Each analysis consisted of 1 block of 50 cycles with 4 s integrations. Five to seven repeated analyses were conducted on each sample solution. The long-term (six months) precision, based on multiple measurements of IAPSO geostandard, is ~0.07 ‰ (2SD; Gao et al., 2022). References Gao, B.Y., Su, B.X., Li, W.J., Yuan, M., Sun, J., Zhao, Y. and Liu, X. (2022) High-precision analysis of calcium isotopes using a Nu Sapphire collision cell (CC)-MC-ICP-MS. Journal of Analytical Atomic Spectrometry 37, 2111-2121. 3 3 Analytical method of Fe isotopes Whole rock dissolution: Iron isotopic analyses were conducted at Metallogenic Elements and Isotopes Laboratory in the Institute of Geology and Geophysics, Chinese Academy of Sciences (IGGCAS), following the protocol described in Wang et al. (2022). 10-30 mg of whole rock powders were dissolved using concentrated HNO3 and HF acids in 7 mL PTFE Teflon square digestion vessels at 160 °C for 2 days. Following the evaporation of HNO3 and HF, the samples were subsequently treated with HNO3 and HCl (1:3) and refluxed at 80 °C for 1 day. Then the samples were dried down and re-dissolved in 1 mL concentrated HCl at 130 °C. Finally, the samples were dried down again and brought into solution in 8 M HCl (+ 0.001% H2O2) for chemical purification. Fe chemical purification: Iron was purified using a two-step ion exchange chromatography. The solution was loaded onto pre-conditioned 2 mL Bio-Rad AGMP-1M resin first. Matrix elements were eluted in the next 37 mL of 8 M HCl. Fe fraction was collected in 18 mL of 2 M HCl afterwards, evaporated to dryness and then redissolved in 1 mL of 8 M HCl (+ 0.001% H2O2) which was loaded onto preconditioned 1 mL Bio-Rad AG-1-X8 resin for second purification. 9 mL of 8 M HCl was used to elute the matrix elements and Fe fraction was collected in the next 10 mL of 0.4 M HCl. The Fe fraction was evaporated to dryness and diluted in 2% HNO3 to 30 ng g-1 for Fe isotopic measurements. The total procedure blank for Fe isotope analyses is < 6 ng. Fe-dominated mineral (without column chromatography): 1-2 separates of Fe-dominated mineral were dissolved with 1 mL concentrated HNO3 acid for 1 day. Then the samples were dried down and diluted in 2% HNO3 to 30 ng g-1 for Fe isotopic measurements. Fe isotopic measurements: Fe isotopic measurements were performed on Nu Sapphire CC-MC-ICP-MS at the collision cell pathway in low resolution mode using the sample-standard bracketing method. Data were collected in static mode, with 54Fe and 56Fe connected to pre-amplifiers fitted with 1011 Ω resistor. Each analysis consisted of a block with 50 cycles of 3 s integration. A 50 s wash was performed in 2% HNO3 between each standard and sample to avoid cross contamination. Longterm reproducibility is 0.03‰ (2SD), evaluated by analyses of BCR-2. Fe isotope results δ56Fe in this study were reported as the per mil deviation relative to standard IRMM-014. Reference Wang, J., Tang, D.M., Su, B.X., Yuan, Q.H., Li, W.J., Gao, B.Y., Chen, K.Y., Bao, Z.A. and Zhao, Y. (2022) High-precision iron isotopic measurements in low resolution using collision cell (CC)-MC-ICP-MS. Journal of Analytical Atomic Spectrometry 37, 1869-1875. 4 4 Analytical method of Cu isotopes Whole rock dissolution: Copper isotopic analyses were conducted at Metallogenic Elements and Isotopes Laboratory in the Institute of Geology and Geophysics, Chinese Academy of Sciences (IGGCAS), following the protocol described in Wang et al. (2022). 10-60 mg of whole rock powders were dissolved using concentrated HNO3 and HF acids in 7 mL PTFE Teflon square digestion vessels at 160 °C for 2 days. Following the evaporation of HNO3 and HF, the samples were subsequently treated with HNO3 and HCl (1:3) and refluxed at 80 °C for 1 day. Then the samples were dried down and re-dissolved in 1 mL concentrated HCl at 130 °C. Finally, the samples were dried down again and brought into solution in 8 M HCl (+ 0.001% H2O2) for chemical purification. Cu chemical purification: The solution was loaded onto pre-conditioned 2 mL Bio-Rad AG-MP-1M resin. Matrix elements were eluted in the next 9 mL of 8 M HCl. Cu fraction was collected in 28 mL of 8 M HCl afterwards and evaporated to dryness. The same column procedure was repeated twice to ensure complete elimination of the matrices. The final Cu eluate was diluted in 2% HNO3 to 250 ng g-1 for Cu isotopic measurements. The total procedure blank for Cu isotope analyses is < 2 ng. Cu-dominated mineral (without column chromatography): 1-2 separates of Cu-dominated mineral were dissolved with 1 mL concentrated HNO3 acid for 1 day. Then the samples were dried down and diluted in 2% HNO3 to 250 ng g-1 for Cu isotopic measurements. Cu isotopic measurements: Cu isotopic measurements were performed on Nu Sapphire CC-MC-ICP-MS at the conventional pathway in low resolution mode using the sample-standard bracketing method. Data were collected in static mode, with 63Cu and 65Cu connected to pre-amplifiers fitted with 1011 Ω resistor. Each analysis consisted of a block with 50 cycles of 3 s integration. A 30 s wash was performed in 2% HNO3 between each standard and sample to avoid cross contamination. Longterm reproducibility is 0.03‰ (2SD), evaluated by analyses of NIST SRM 3114. Cu isotope results δ65Cu in this study were reported as the per mil deviation relative to standard NIST SRM 976. Reference Wang, J., Su, B.X., Tang, D.M., Yuan, Q.H., Li, W.J., Gao, B.Y., Bao, Z.A. and Zhao, Y. (2022) High-precision copper isotopic analysis using Nu Sapphire MC-ICP-MS. Journal of Analytical Atomic Spectrometry 37, 2589-2598. 5 5 Analytical method of Zn isotopes Whole rock dissolution: Zinc isotopic analyses were conducted at Metallogenic Elements and Isotopes Laboratory in the Institute of Geology and Geophysics, Chinese Academy of Sciences (IGGCAS), following the protocol described in Wang et al. (2022). 10-60 mg of whole rock powders were dissolved using concentrated HNO3 and HF acids in 7 mL PTFE Teflon square digestion vessels at 160 °C for 2 days. Following the evaporation of HNO3 and HF, the samples were subsequently treated with HNO3 and HCl (1:3) and refluxed at 80 °C for 1 day. Then the samples were dried down and re-dissolved in 1 mL concentrated HCl at 130 °C. Finally, the samples were dried down again and brought into solution in 8 M HCl (+ 0.001% H2O2) for chemical purification. Zn chemical purification: Zinc was purified using a two-step ion exchange chromatography. The solution was loaded onto pre-conditioned 2 mL Bio-Rad AGMP-1M resin first. Matrix elements were eluted in the next 37 mL of 8 M HCl, 18 mL of 2 M HCl and 2 mL of 0.5 M HNO3 sequentially. Zn fraction was collected in 10 mL of 0.5 M HNO3 afterwards, evaporated to dryness and then redissolved in 1 mL of 8 M HCl (+ 0.001% H2O2) which was loaded onto pre-conditioned 1 mL Bio-Rad AG-1-X8 resin for second purification. 9 mL of 8 M HCl and 10 mL of 0.4 M HCl were used to elute the matrix elements, and Zn fraction was collected in 7 mL of 0.5 M HNO3, which was evaporated to dryness and diluted in 2% HNO3 to 500 ng g-1 for Zn isotopic measurements. The total procedure blank for Zn isotope analyses is < 5 ng. Zn-dominated mineral (without column chromatography): 1-2 separates of Zn-dominated mineral were dissolved with 1 mL concentrated HNO3 acid for 1 day. Then the samples were dried down and diluted in 2% HNO3 to 500 ng g-1 for Zn isotopic measurements. Zn isotopic measurements: Zn isotopic measurements were performed on Nu Sapphire CC-MC-ICP-MS at the conventional pathway in low resolution mode using the sample-standard bracketing method. Beams of 64Zn, 66Zn, 67Zn and 68Zn were collected in Faraday cups in static mode, with 62Ni monitor to correct for interference 64Ni on 64Zn. Each analysis consisted of a block with 50 cycles of 3 s integration. A 30 s wash was performed in 2% HNO3 between each standard and sample to avoid cross contamination. Long-term reproducibility is 0.03‰ (2SD), evaluated by analyses of NIST SRM 3168a. Zn isotope results δ66Zn in this study were reported as the per mil deviation relative to standard JMC 3-0749L. 6 6 Analytical methods of Cu-Fe-Zn isotopes Whole rock dissolution: Cu-Fe-Zn isotopic analyses were conducted at Metallogenic Elements and Isotopes Laboratory in the Institute of Geology and Geophysics, Chinese Academy of Sciences (IGGCAS), following the protocol described in Wang et al. (2022). 10-60 mg of whole rock powders were dissolved using concentrated HNO3 and HF acids in 7 mL PTFE Teflon square digestion vessels at 160 °C for 2 days. Following the evaporation of HNO3 and HF, the samples were subsequently treated with HNO3 and HCl (1:3) and refluxed at 80 °C for 1 day. Then the samples were dried down and re-dissolved in 1 mL concentrated HCl at 130 °C. Finally, the samples were dried down again and brought into solution in 8 M HCl (+ 0.001% H2O2) for chemical purification. Cu-Fe-Zn chemical purification: Cu-Fe-Zn was purified using a two-step ion exchange chromatography. The solution was loaded onto pre-conditioned 2 mL BioRad AG-MP-1M resin first. Matrix elements were eluted in the next 9 mL of 8 M HCl. Cu fraction was collected in 28 mL of 8 M HCl afterwards. And then, Fe fraction was collected in 18 mL of 2 M HCl. After that, 2 mL of 0.5 M HNO3 was added to resin and Zn fraction was collected in 10 mL of 0.5 M HNO3 sequentially. Cu, Fe and Zn fractions was evaporated to dryness and then redissolved in 1 mL of 8 M HCl (+ 0.001% H2O2) separately for second chemical purification. For Cu, the same column procedure was repeated once to ensure complete elimination of the matrices. As for Fe or Zn, they were loaded onto pre-conditioned 1 mL Bio-Rad AG-1-X8 resin for second purification. 9 mL of 8 M HCl was used to elute the matrix elements and Fe fraction was collected in the next 10 mL of 0.4 M HCl. Zn fraction was collected in 7 mL of 0.5 M HNO3 afterwards. The final Cu, Fe and Zn eluates were evaporated to dryness and diluted in 2% HNO3 to 250ng g-1 (Cu), 30 ng g-1 (Fe) or 500 ng g-1 (Zn) for isotopic measurements. The total procedure blank for Cu, Fe and Zn isotope analyses are < 2 ng, 5 ng and 6 ng, respectively. Cu/Fe/Zn-dominated mineral (without column chromatography): 1-2 separates of Cu/Fe/Zn-dominated mineral were dissolved with 1 mL concentrated HNO3 acid for 1 day. Then the samples were dried down and diluted in 2% HNO3 to 250ng g-1 (Cu), 30 ng g-1 (Fe) or 500 ng g-1 (Zn) for isotopic measurements. Cu/Fe/Zn isotopic measurements: Cu, Fe and Zn isotopic measurements were performed on Nu Sapphire CC-MC-ICP-MS at the conventional pathway (Cu and Zn) or the collision cell pathway (Fe) in low resolution mode using the sample-standard bracketing method. Data were collected in static mode, with connected to preamplifiers fitted with 1011 Ω resistor. Each analysis consisted of a block with 50 cycles of 3 s integration. A 30 s (Cu and Zn) or 50 s (Fe) wash was performed in 2% HNO3 between each standard and sample to avoid cross contamination. Longterm reproducibility is 0.03‰ (2SD) for Cu, Fe and Zn isotopic measurements. Cu, Fe and Zn isotope results were reported as the per mil deviation relative to standard NIST SRM 976, IRMM-014 and JMC 3-0749L, respectively. Reference Wang, J., Su, B.X., Tang, D.M., Yuan, Q.H., Li, W.J., Gao, B.Y., Bao, Z.A. and Zhao, Y. (2022) High-precision copper isotopic analysis using Nu Sapphire MC-ICP-MS. Journal of Analytical Atomic Spectrometry 37, 2589-2598. Wang, J., Tang, D.M., Su, B.X., Yuan, Q.H., Li, W.J., Gao, B.Y., Chen, K.Y., Bao, Z.A. and Zhao, Y. (2022) High-precision iron isotopic measurements in low resolution using collision cell (CC)-MC-ICP-MS. Journal of Analytical Atomic Spectrometry 37, 1869-1875. 7 7 Analytical method of Li isotopes Lithium isotopic analyses were conducted at Metallogenic Elements and Isotopes Lab in the Institute of Geology and Geophysics, Chinese Academy of Sciences (IGGCAS), following the protocol described in Liu et al. (2023). Approximately 2–30 mg of sample powders were weighed and digested using mixture of concentrated HNO3 and HF. The digested sample solutions were evaporated to dryness and then treated sequentially with aqua regia and 6 mol L-1 HCl. After evaporating the solutions, the final residues were fully dissolved in 0.2 mol L-1 HCl prior to column separation. The sample solution was loaded onto pre-conditioned 2.7 mL Bio-Rad AG50W-X12 (200-400 mesh) resin and then eluted with a 17 mL of 0.2 mol L-1 HCl to remove the matrix elements. The Li fraction containing ~ 100% of total Li was collected with 24 mL 0.2 mol L-1 HCl and then dried down. The final Li solution was redissolved with 2 % HNO3 ready for measurement. Lithium isotopic measurements were performed on the Nu Sapphire CC-MC-ICP-MS (Nu Instruments, Wrexham, UK) using the collision cell (low-energy) path with the low-resolution mode. An autosampler SC-2DX (Elemental Scientific, U.S.A.) was connected to an Apex Omega desolvation nebulizer (Elemental Scientific, U.S.A.) system for sample introduction. Faraday cups L6 and H9 were both connected to pre-amplifiers each fitted with a conventional 1011 Ω resistor and chosen to collect 6Li+ and 7Li+ beams in static mode, respectively. Li isotopic data are reported in δ notation relative to the LSVEC standard (Li2CO3), using the standard-sample bracketing technique for instrumental mass fractionation correction: Each analysis consisted of 1 block of 30 cycles with 4 s integrations. Five to seven repeated analyses were conducted on each sample solution. The long-term (eight months) precision, based on multiple measurements of BCR-2 and JG-2 geostandards, is ~0.20 ‰ (2SD; Liu et al., 2023). References Liu, S.K., Li, W.J., Su, B.X., Gao, B.Y., Wang, J., Wang, C.L., Luo, Y., Yan, L.Z. and Zhao, Y. (2023) High-precision lithium isotopic analysis using the Nu Sapphire MC-ICP-MS. Journal of Analytical Atomic Spectrometry, doi: 10.1039/D1032JA00371F. 8 8 Analytical method of Re-Os dating for metal sulfide Rhenium-osmium isotopic analysis was carried out at Metallogenic Elements and Isotopes Lab in the Institute of Geology and Geophysics, Chinese Academy of Sciences. The suitable amount of weighed sample together with known amounts of 185Re and 190Os spike, was treated with a HCl–HNO solution in a sealed Carius tube 3 for 24 h at 220°C (Gao et al., 2019).The Os separation procedure employed in this study involved the directed distillation technique is reported by Jin et al. (2013). The Re separation procedure used in the present study is reported by Gao et al. (2022). Both the Os isotopic ratio and the Re isotopic ratio were determined using a high resolution inductively coupled plasma mass spectrometer (Thermo Element XR). The measured isotopic data were further corrected for procedural blank contributions, instrumental mass fractionation. Two Chinese national Re-Os reference materials (JCBY and XTC) were determined to evaluate the analytical quality. The analytical results of JCBY and XTC are in good agreement with the certified values, which were reported by Qu et al. (2013) and Li et al. (2022). The Re–Os isochron line is constructed in this study through a bidirectional-uncertainty weighted regression analysis using a statistical soft-ware package, Isoplot/Ex v. 3.75 (Ludwig, 2012). References Gao, B.Y., Li, W.J., Jin, X.D. and Zhang, L.C. (2019) Application of addition HClO4 to improve the dissolution process and sensitivity of Os for low-concentration of Os in pyrite. Microchemical Journal 150, 104165. Gao, B.Y., Li, W.J., Chu, Z.Y. and Zhang, L.C. (2022) An improved solvent extraction procedure for Re isotopic measurements. Microchemical Journal 180, 107568. Jin, X.D., Li, W.J., Xiang, P., Sakyi, P.A., Zhu, M.T. and Zhang, L.C. (2013) A contribution to common Carius tube distillation techniques. Journal of Analytical Atomic Spectrometry 28, 396-404. Li, W.J., Jin, X.D., Gao, B.Y., Zhou, L.M., Yang, G., Li, C., Stein, H., Hannah, J., Du, A.D., Qu, W.J., Chu, Z.Y., Wang, Y.T. and Zhang, L.C. (2022) Chalcopyrite from the Xiaotongchang Cu deposit: A new sulfide reference material for low-level Re-Os geochronology. Geostandards and Geoanalytical Research 46, 321-332. Qu, W.J. and Li, C. (2011) Discussion and evaluation of traceability and total uncertainty for the determination results of copper-nickel-sulfide Re-Os reference materials. Rock and Mineral Analysis 30, 664-668. Ludwig, K.R. (2012) User’s manual for Isoplot 3.75: A geochronological tool kit for Microsoft Excel, Berkeley Geochronology Center Special Publication No. 5. 9 9 Analytical method for in situ trace element analysis by LASF-ICP-MS Trace elements analyses were performed on a 193 nm Coherent GeoLas Pro ArF Excimer laser coupled to an Element XR SF-ICP-MS instrument at Metallogenetic Elements and Isotopes Laboratory in the Institute of Geology and Geophysics, Chinese Academy of Sciences (IGGCAS). Ablation was performed using 44 μm diameter ablating spots at 5 Hz with an energy of 5 J/cm2 for 60 s after measuring the gas blank for 30 s. A pre-ablation of three laser pulses was done prior to each analysis, and a 30 s washout between analyses was used. The carrier (He) and make-up gas (Ar) flows were optimized by a spot ablation of the NIST SRM 612 to obtain maximum signal intensities, while keeping ThO/Th at < 0.5 ‰ and U/Th of 0.95-1.05. NIST SRM 610 reference glass was used as calibration material, and USGS BCR-2G as well as BIR-1G were analyzed for data quality (Li et al., 2023). Iron (57Fe) was used as an internal standard. control. Data reduction were obtained using the GLITTER program. For most trace elements (>0.10 μg g-1), the accuracy is better than ±10 % with analytical precision (1 RSD) of ±10%. References Li, W.J., Wang, J., Cui, M.M., Liu, X., Jia, L.H., Chen, K.Y., Wu, S.T., Gao, B.Y., Xue, D.S., Liu, Y.H., Li, C., Luo, Y. and Su, B.X. (2023) Natural clinopyroxene reference materials for in situ microanalysis. Geostandards and Geoanalytical Research, doi: org/10.1111/ggr.12471. 10