Jadeite artefacts at Maya sites are normally associated with ritual and ceremonial locations, wit... more Jadeite artefacts at Maya sites are normally associated with ritual and ceremonial locations, with high-quality jadeite reserved for elite objects. The discovery of a jadeite gouge with a wooden handle at a Classic Maya saltworking site submerged by sea-level rise-Ek Way Nal, Belize-is therefore unexpected and provides new information about the utilitarian use of this stone. The extremely high quality of this jadeite tool is particularly surprising, offering new insight into the Classic Maya exchange systems and the role of salt makers such as those based at Ek Way Nal.
Clinopyroxene (Cpx) is a principal upper-mantle phase for concentrating large cations but has not... more Clinopyroxene (Cpx) is a principal upper-mantle phase for concentrating large cations but has not been viewed as a major crystal-chemical reservoir for K because K ϩ is considered too large to enter the largest site, M2, in the pyroxene structure. Accumulating data from high-pressure conditions indicate this inference is incorrect, so multianvil experiments have been performed to evaluate maximal K solubility in Cpx at high pressure. End members and mixtures of diopside, jadeite, and kosmochlor have been mixed with K 2 CO 3 , KHCO 3 or both in welded platinum capsules and heated typically for 24 h in the range of 5 to 14 GPa and 1200 to 1700 ЊC. These experiments produced K-rich Cpx in solid solutions by means of a fictive Kcpx component (KCrSi 2 O 6 or KAlSi 2 O 6). The maximum K 2 O content obtained is 4.7 wt% in a Cpx (Di 38 Ko 39 Kcpx 22 En 1) formed from a 50:50 Di ϩ Ko mixture at 10 GPa, 1400 ЊC. K uptake and partitioning is dependent positively on P, complexly on Cpx composition but not demonstrably on T. Cpx/liq is in the range of 0.03-0.1 and Cpx/liq varies D D K O Na O 2 2 from 0.5 to 5, although the variations for each with Cpx composition are different. In diopside, Kcpx increases are always accompanied by increases in Nacpx, and cooperative Nacpx solution is necessary for Kcpx solution in the compositional systems examined. K appears to be accommodated in the M2 site of the Cpx structure by two types of spatial averaging: a large average M2 site, as in the case of Di, ameliorates the fit, but local accommodation by size averaging with a smaller M2 occupant, presumably Na, appears necessary, suggesting that the polyhedral compressibility of Na and K are large in comparison with Ca. In application to Cpx inclusions in diamond, the data here imply that a chromium diopside with ϳ1 wt% K 2 O forms in the presence of a C-rich melt with 15-28 wt% K 2 O. Notes: 1 is 39849, Wakefield Di; 2 is 100634, Zabargad Hi-Al En; 3 is 100634, Zabargad Low-Al En; 4 is Synthetic Kosmochlor; 5 is 33399 Manzanal Jd. * Fe 3ϩ determined by cation sum and charge balancing.
The crystal structure of the most K-rich natural pyroxene ever reported, a chromian diopside with... more The crystal structure of the most K-rich natural pyroxene ever reported, a chromian diopside with 1.5 wt% K20, has been refined (diffractometer data, filtered MoKa radiation, by least-squares using XTAL to Ru = 3.2%) to examine the effect of K on the average structure. The crystal with structural formula Cao.8oKo.o73Nao.o23M&>.95Feo.o6Cro.Q7Alo.o2Si206 was found as an inclusion in a Koffiefontein diamond. The refined structure is typical of clinopyroxene on the diopside-enstatite join: Mg in M2 leads to distortion that is modeled by site splitting, with M2' (Mg + Fe) displaced 0.33 A from M2 (Ca + K + Na). Assignment of K to M2 is required to account for the electron density at that site. The average of eight M2-0 distances (2.504 A) is slightly larger than for diopside (2.498 A). The effect of K on the average M2-0 distance can be seen by calculating the average cation radius of atoms at M2 (+ M2') from the occupancy: 0.798.1.12 A ([8ICa)+ 0.073 .1.51 (K) + 0.023.1.18 (Na) + 0.036.0.92 (Fe) + 0.070'0.89 (Mg) = 1.127-?:.R ([8ICa). The large size of K is mostly offset by Mg + Fe in M2' in the diopside-like structure; this sizedistortion balancing may facilitate K uptake in mantle clinopyroxene in K-rich environments. Large apparent thermal motion parameters of most atomic sites indicate sizable local distortions of the structure from substitution of K into M2.
The crystal structure of synthetic kosmochlor, NaCrSi 2 O 6 , was studied using single crystal X-... more The crystal structure of synthetic kosmochlor, NaCrSi 2 O 6 , was studied using single crystal X-ray diffraction at high pressure. A four-pin diamond anvil cell, with 4:1 methanol:ethanol pressure medium, was used to achieve pressures to 9.28 GPa. Unit-cell data were collected at 20 pressures, and intensity data were collected at 13 of these pressures. Fitting the P-V data to a third-order Birch-Murnaghan equation yields V 0 = 418.84(3) Å 3 , K 0 = 134(1) GPa-1 , and K 0 ' = 2.0(3). Anisotropic compression was observed with unit strain axial ratios of 1:1.82:2.08. The CrO 6 octahedron has a bulk modulus K 0 = 90(16) GPa-1 , while the SiO 4 tetrahedron has K 0 = 313(55) GPa-1 , both with K 0 ' ∫ 4. An o-type rotation of the O3-O3-O3 linkage was observed with pressure, with-O3-O3-O3 decreasing from 172.8(2)∞ to 166.1(7)∞. Compression in kosmochlor is related to the stacking directions of distorted cubic closest packed O atom monolayers. Unit strain ellipsoids for diopside, hedenbergite, spodumene (C2/c and P2 1 /c), LiScSi 2 O 6 (C2/c and P2 1 /c), clinoenstatite, orthoenstatite, and Mg 1.54 Li .23 Sc .23 Si 2 O 6 (Pbcn and P2 1 cn) were generated and discussed in terms of closest packing systematics. A relationship between the anisotropy of compression of olivines and pyroxenes is established. A strategy to determine not only the direction of a stress field in deformed rocks, but also an estimate of the magnitude of stress is discussed in terms of comparing the anisotropy of olivine and pyroxene.
Highlights ► B and Li isotopes in situ by LA-MC-ICP-MS ► Analyses in silicates (pyroxene, mica, s... more Highlights ► B and Li isotopes in situ by LA-MC-ICP-MS ► Analyses in silicates (pyroxene, mica, serpentine) and tourmaline standard material ► LA-MC-ICP-MS data compared to traditional methods (SIMS and MC-ICP-MS) ► Suitable method for B isotopes for all minerals considered, short time span. ► Suitable method for Li isotopes for pyroxene and mica.
The reason for the rarity of eckermannite compositions are examined and discussed based on consid... more The reason for the rarity of eckermannite compositions are examined and discussed based on considerations on the short-range order of A cations and W anions.
2008 33rd International Conference on Infrared, Millimeter and Terahertz Waves, 2008
ABSTRACT Mineralogical characterization and far-infrared spectroscopy of laboratory analogues in ... more ABSTRACT Mineralogical characterization and far-infrared spectroscopy of laboratory analogues in the wavelength range 57 - 210 mum is performed for interpreting data from Herschelpsilas Photodetector Array Camera and Spectrometer (PACS).
The paragon of physical perfection and a sparkling example of Earth's forces at work, the di... more The paragon of physical perfection and a sparkling example of Earth's forces at work, the diamond has fascinated all realms of society, from starlets to scientists. The Nature of Diamonds is a comprehensive look at nature's most coveted gem. A handsome, large-format book, The Nature of Diamonds is an authoritative and richly-illustrated tribute to the diamond. Leading geologists, gemologists, physicists, and cultural observers cover every facet of the stone, from its formation in the depths of the Earth, its ascent to the surface, and its economic, regal, social, and technological roles. Cutting-edge research takes the reader to the frontiers of diamond exploration and exploitation, from the Arctic wastes to the laboratories where diamonds are created for massive road shredders that rip up and then re-create superhighways. Here also is an overview of cutting, from the rough stones in Roman rings to the highly-faceted stones we see today, and a glimpse into the business of ...
percent of the total concentration of I-, Oreanizatiott (Clarendon. Oxford. 1983). too small to b... more percent of the total concentration of I-, Oreanizatiott (Clarendon. Oxford. 1983). too small to be observed visuallv as in the 4. J. b.~urray;athemat;cal ~i o l o i y (Springer-~eroriginal experiment.
Polarized infrared (IR) spectra of olivine single crystals from 17 different localities show a tr... more Polarized infrared (IR) spectra of olivine single crystals from 17 different localities show a tremendous variability in both mode and abundance of hydroxide (OH) incorporation. Kimberlitic olivines contain the most total OH at an estimated concentration level of 976 H/106Si, whereas olivines from basalts contain the least at 3 H/106Si. Olivines of metamorphic and hydrothermal origin have widely varying concentration levels intermediate between those of basalts and kimberlites. Over 30 distinct OH absorption bands have been identified. Most of these bands are not unique to individual localities but may be found in samples from several different localities. Pleochroism is consistent among localities, but relative band intensities vary. No evidence is found for molecular H2 in olivine. Hydrous minerals have been identified in olivine by their characteristic OH absorption bands. Serpentine is commonly found and is clearly distinguishable from intrinsic OH. Talc is present in one sample. Prominent OH bands at 3572 and 3525 cm-1 are attributed to humite group minerals. San Carlos, Arizona, olivines annealed in the presence of H20 develop absorption bands which are found in natural samples, however the OH absorption spectra of these annealed olivines are not identical to those of any single natural crystal. Sharp-band OH abundances in annealed samples are an order of magnitude lower than the maximum measured in natural specimens. The mechanical properties determined from these annealed olivines may not be directly applicable to mantle olivine because both the OH sites and concentrations are different.
The lower Cretaceous Yixian and Jiufotang formations contain numerous exceptionally wellpreserved... more The lower Cretaceous Yixian and Jiufotang formations contain numerous exceptionally wellpreserved invertebrate, vertebrate and plant fossils that comprise the Jehol Biota. Freshwater and terrestrial fossils of the biota usually occur together within some horizons and have been interpreted as deposits of mass mortality events. The nature of the events and the mechanisms behind the exceptional preservation of the fossils, however, are poorly understood. Here, after examining and analysing sediments and residual fossils from several key horizons, we postulate that the causal events were mainly phreatomagmatic eruptions. Pyroclastic density currents were probably responsible for the major causalities and for transporting the bulk of the terrestrial vertebrates from different habitats, such as lizards, birds, non-avian dinosaurs and mammals, into lacustrine environments for burial. Terrestrial vertebrate carcasses transported by and sealed within the pyroclastic flows were clearly preserved as exceptional fossils through this process.
Page 1. Geology doi: 10.1130/0091-7613(1999)027<0629:GJAAWF>2.3.CO;2 1999;27;629-63... more Page 1. Geology doi: 10.1130/0091-7613(1999)027<0629:GJAAWF>2.3.CO;2 1999;27;629-632 Geology Craig A. Johnson and George E. Harlow serpentinizing fluids deep within a subduction zone Guatemala jadeitites and albitites were formed by deuterium-rich ...
The jadeitite from Myanmar is the most important commercial source on Earth, and its mineralogy p... more The jadeitite from Myanmar is the most important commercial source on Earth, and its mineralogy perhaps the most diverse. More than thirty mineral species, including jadeite, omphacite, kosmochlor, Cr-bearing jadeite
The Photoatlas is fundamentally a compendium of photomicrographs of inclusions in gemstones organ... more The Photoatlas is fundamentally a compendium of photomicrographs of inclusions in gemstones organized and described in a fashion to enhance the gemologist’s skills at identifying and interpreting such inclusions. The second volume proceeds from an earlier volume that was published in 1986, and fundamentally updates the older volume to 2005. This volume, the third, focuses on the so-called “precious stones”—diamond, ruby, emerald, and sapphire, but with significant additions relating to “treated” gems and synthetics (both of the actual species as well as simulants). Eduard Gubelin, a dean of the gemological community (deceased in 2005), and John Koivula, a renowned gemologist and inclusion expert at the Gemological Institute of America (GIA), have been the experts in this field, so the book is a testament and proof of their experience and expertise with respect to inclusions in gemstones and gemology, more generally. Moreover, as the authors appreciate the beauty as much as the information revealed by inclusions, the Photoatlas can be viewed as a paean to gem inclusions as art. The images are superb and printed in high quality on heavy paper with attention to color correction (typically a problem for colored stones and inclusions). The authors also justifiably point out that inclusions and their identification can be critical, perhaps the only non-destructive and ready …
Jadeite artefacts at Maya sites are normally associated with ritual and ceremonial locations, wit... more Jadeite artefacts at Maya sites are normally associated with ritual and ceremonial locations, with high-quality jadeite reserved for elite objects. The discovery of a jadeite gouge with a wooden handle at a Classic Maya saltworking site submerged by sea-level rise-Ek Way Nal, Belize-is therefore unexpected and provides new information about the utilitarian use of this stone. The extremely high quality of this jadeite tool is particularly surprising, offering new insight into the Classic Maya exchange systems and the role of salt makers such as those based at Ek Way Nal.
Clinopyroxene (Cpx) is a principal upper-mantle phase for concentrating large cations but has not... more Clinopyroxene (Cpx) is a principal upper-mantle phase for concentrating large cations but has not been viewed as a major crystal-chemical reservoir for K because K ϩ is considered too large to enter the largest site, M2, in the pyroxene structure. Accumulating data from high-pressure conditions indicate this inference is incorrect, so multianvil experiments have been performed to evaluate maximal K solubility in Cpx at high pressure. End members and mixtures of diopside, jadeite, and kosmochlor have been mixed with K 2 CO 3 , KHCO 3 or both in welded platinum capsules and heated typically for 24 h in the range of 5 to 14 GPa and 1200 to 1700 ЊC. These experiments produced K-rich Cpx in solid solutions by means of a fictive Kcpx component (KCrSi 2 O 6 or KAlSi 2 O 6). The maximum K 2 O content obtained is 4.7 wt% in a Cpx (Di 38 Ko 39 Kcpx 22 En 1) formed from a 50:50 Di ϩ Ko mixture at 10 GPa, 1400 ЊC. K uptake and partitioning is dependent positively on P, complexly on Cpx composition but not demonstrably on T. Cpx/liq is in the range of 0.03-0.1 and Cpx/liq varies D D K O Na O 2 2 from 0.5 to 5, although the variations for each with Cpx composition are different. In diopside, Kcpx increases are always accompanied by increases in Nacpx, and cooperative Nacpx solution is necessary for Kcpx solution in the compositional systems examined. K appears to be accommodated in the M2 site of the Cpx structure by two types of spatial averaging: a large average M2 site, as in the case of Di, ameliorates the fit, but local accommodation by size averaging with a smaller M2 occupant, presumably Na, appears necessary, suggesting that the polyhedral compressibility of Na and K are large in comparison with Ca. In application to Cpx inclusions in diamond, the data here imply that a chromium diopside with ϳ1 wt% K 2 O forms in the presence of a C-rich melt with 15-28 wt% K 2 O. Notes: 1 is 39849, Wakefield Di; 2 is 100634, Zabargad Hi-Al En; 3 is 100634, Zabargad Low-Al En; 4 is Synthetic Kosmochlor; 5 is 33399 Manzanal Jd. * Fe 3ϩ determined by cation sum and charge balancing.
The crystal structure of the most K-rich natural pyroxene ever reported, a chromian diopside with... more The crystal structure of the most K-rich natural pyroxene ever reported, a chromian diopside with 1.5 wt% K20, has been refined (diffractometer data, filtered MoKa radiation, by least-squares using XTAL to Ru = 3.2%) to examine the effect of K on the average structure. The crystal with structural formula Cao.8oKo.o73Nao.o23M&>.95Feo.o6Cro.Q7Alo.o2Si206 was found as an inclusion in a Koffiefontein diamond. The refined structure is typical of clinopyroxene on the diopside-enstatite join: Mg in M2 leads to distortion that is modeled by site splitting, with M2' (Mg + Fe) displaced 0.33 A from M2 (Ca + K + Na). Assignment of K to M2 is required to account for the electron density at that site. The average of eight M2-0 distances (2.504 A) is slightly larger than for diopside (2.498 A). The effect of K on the average M2-0 distance can be seen by calculating the average cation radius of atoms at M2 (+ M2') from the occupancy: 0.798.1.12 A ([8ICa)+ 0.073 .1.51 (K) + 0.023.1.18 (Na) + 0.036.0.92 (Fe) + 0.070'0.89 (Mg) = 1.127-?:.R ([8ICa). The large size of K is mostly offset by Mg + Fe in M2' in the diopside-like structure; this sizedistortion balancing may facilitate K uptake in mantle clinopyroxene in K-rich environments. Large apparent thermal motion parameters of most atomic sites indicate sizable local distortions of the structure from substitution of K into M2.
The crystal structure of synthetic kosmochlor, NaCrSi 2 O 6 , was studied using single crystal X-... more The crystal structure of synthetic kosmochlor, NaCrSi 2 O 6 , was studied using single crystal X-ray diffraction at high pressure. A four-pin diamond anvil cell, with 4:1 methanol:ethanol pressure medium, was used to achieve pressures to 9.28 GPa. Unit-cell data were collected at 20 pressures, and intensity data were collected at 13 of these pressures. Fitting the P-V data to a third-order Birch-Murnaghan equation yields V 0 = 418.84(3) Å 3 , K 0 = 134(1) GPa-1 , and K 0 ' = 2.0(3). Anisotropic compression was observed with unit strain axial ratios of 1:1.82:2.08. The CrO 6 octahedron has a bulk modulus K 0 = 90(16) GPa-1 , while the SiO 4 tetrahedron has K 0 = 313(55) GPa-1 , both with K 0 ' ∫ 4. An o-type rotation of the O3-O3-O3 linkage was observed with pressure, with-O3-O3-O3 decreasing from 172.8(2)∞ to 166.1(7)∞. Compression in kosmochlor is related to the stacking directions of distorted cubic closest packed O atom monolayers. Unit strain ellipsoids for diopside, hedenbergite, spodumene (C2/c and P2 1 /c), LiScSi 2 O 6 (C2/c and P2 1 /c), clinoenstatite, orthoenstatite, and Mg 1.54 Li .23 Sc .23 Si 2 O 6 (Pbcn and P2 1 cn) were generated and discussed in terms of closest packing systematics. A relationship between the anisotropy of compression of olivines and pyroxenes is established. A strategy to determine not only the direction of a stress field in deformed rocks, but also an estimate of the magnitude of stress is discussed in terms of comparing the anisotropy of olivine and pyroxene.
Highlights ► B and Li isotopes in situ by LA-MC-ICP-MS ► Analyses in silicates (pyroxene, mica, s... more Highlights ► B and Li isotopes in situ by LA-MC-ICP-MS ► Analyses in silicates (pyroxene, mica, serpentine) and tourmaline standard material ► LA-MC-ICP-MS data compared to traditional methods (SIMS and MC-ICP-MS) ► Suitable method for B isotopes for all minerals considered, short time span. ► Suitable method for Li isotopes for pyroxene and mica.
The reason for the rarity of eckermannite compositions are examined and discussed based on consid... more The reason for the rarity of eckermannite compositions are examined and discussed based on considerations on the short-range order of A cations and W anions.
2008 33rd International Conference on Infrared, Millimeter and Terahertz Waves, 2008
ABSTRACT Mineralogical characterization and far-infrared spectroscopy of laboratory analogues in ... more ABSTRACT Mineralogical characterization and far-infrared spectroscopy of laboratory analogues in the wavelength range 57 - 210 mum is performed for interpreting data from Herschelpsilas Photodetector Array Camera and Spectrometer (PACS).
The paragon of physical perfection and a sparkling example of Earth's forces at work, the di... more The paragon of physical perfection and a sparkling example of Earth's forces at work, the diamond has fascinated all realms of society, from starlets to scientists. The Nature of Diamonds is a comprehensive look at nature's most coveted gem. A handsome, large-format book, The Nature of Diamonds is an authoritative and richly-illustrated tribute to the diamond. Leading geologists, gemologists, physicists, and cultural observers cover every facet of the stone, from its formation in the depths of the Earth, its ascent to the surface, and its economic, regal, social, and technological roles. Cutting-edge research takes the reader to the frontiers of diamond exploration and exploitation, from the Arctic wastes to the laboratories where diamonds are created for massive road shredders that rip up and then re-create superhighways. Here also is an overview of cutting, from the rough stones in Roman rings to the highly-faceted stones we see today, and a glimpse into the business of ...
percent of the total concentration of I-, Oreanizatiott (Clarendon. Oxford. 1983). too small to b... more percent of the total concentration of I-, Oreanizatiott (Clarendon. Oxford. 1983). too small to be observed visuallv as in the 4. J. b.~urray;athemat;cal ~i o l o i y (Springer-~eroriginal experiment.
Polarized infrared (IR) spectra of olivine single crystals from 17 different localities show a tr... more Polarized infrared (IR) spectra of olivine single crystals from 17 different localities show a tremendous variability in both mode and abundance of hydroxide (OH) incorporation. Kimberlitic olivines contain the most total OH at an estimated concentration level of 976 H/106Si, whereas olivines from basalts contain the least at 3 H/106Si. Olivines of metamorphic and hydrothermal origin have widely varying concentration levels intermediate between those of basalts and kimberlites. Over 30 distinct OH absorption bands have been identified. Most of these bands are not unique to individual localities but may be found in samples from several different localities. Pleochroism is consistent among localities, but relative band intensities vary. No evidence is found for molecular H2 in olivine. Hydrous minerals have been identified in olivine by their characteristic OH absorption bands. Serpentine is commonly found and is clearly distinguishable from intrinsic OH. Talc is present in one sample. Prominent OH bands at 3572 and 3525 cm-1 are attributed to humite group minerals. San Carlos, Arizona, olivines annealed in the presence of H20 develop absorption bands which are found in natural samples, however the OH absorption spectra of these annealed olivines are not identical to those of any single natural crystal. Sharp-band OH abundances in annealed samples are an order of magnitude lower than the maximum measured in natural specimens. The mechanical properties determined from these annealed olivines may not be directly applicable to mantle olivine because both the OH sites and concentrations are different.
The lower Cretaceous Yixian and Jiufotang formations contain numerous exceptionally wellpreserved... more The lower Cretaceous Yixian and Jiufotang formations contain numerous exceptionally wellpreserved invertebrate, vertebrate and plant fossils that comprise the Jehol Biota. Freshwater and terrestrial fossils of the biota usually occur together within some horizons and have been interpreted as deposits of mass mortality events. The nature of the events and the mechanisms behind the exceptional preservation of the fossils, however, are poorly understood. Here, after examining and analysing sediments and residual fossils from several key horizons, we postulate that the causal events were mainly phreatomagmatic eruptions. Pyroclastic density currents were probably responsible for the major causalities and for transporting the bulk of the terrestrial vertebrates from different habitats, such as lizards, birds, non-avian dinosaurs and mammals, into lacustrine environments for burial. Terrestrial vertebrate carcasses transported by and sealed within the pyroclastic flows were clearly preserved as exceptional fossils through this process.
Page 1. Geology doi: 10.1130/0091-7613(1999)027<0629:GJAAWF>2.3.CO;2 1999;27;629-63... more Page 1. Geology doi: 10.1130/0091-7613(1999)027<0629:GJAAWF>2.3.CO;2 1999;27;629-632 Geology Craig A. Johnson and George E. Harlow serpentinizing fluids deep within a subduction zone Guatemala jadeitites and albitites were formed by deuterium-rich ...
The jadeitite from Myanmar is the most important commercial source on Earth, and its mineralogy p... more The jadeitite from Myanmar is the most important commercial source on Earth, and its mineralogy perhaps the most diverse. More than thirty mineral species, including jadeite, omphacite, kosmochlor, Cr-bearing jadeite
The Photoatlas is fundamentally a compendium of photomicrographs of inclusions in gemstones organ... more The Photoatlas is fundamentally a compendium of photomicrographs of inclusions in gemstones organized and described in a fashion to enhance the gemologist’s skills at identifying and interpreting such inclusions. The second volume proceeds from an earlier volume that was published in 1986, and fundamentally updates the older volume to 2005. This volume, the third, focuses on the so-called “precious stones”—diamond, ruby, emerald, and sapphire, but with significant additions relating to “treated” gems and synthetics (both of the actual species as well as simulants). Eduard Gubelin, a dean of the gemological community (deceased in 2005), and John Koivula, a renowned gemologist and inclusion expert at the Gemological Institute of America (GIA), have been the experts in this field, so the book is a testament and proof of their experience and expertise with respect to inclusions in gemstones and gemology, more generally. Moreover, as the authors appreciate the beauty as much as the information revealed by inclusions, the Photoatlas can be viewed as a paean to gem inclusions as art. The images are superb and printed in high quality on heavy paper with attention to color correction (typically a problem for colored stones and inclusions). The authors also justifiably point out that inclusions and their identification can be critical, perhaps the only non-destructive and ready …
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