In-Situ Study of Mineralogy, Gemology and Progress in Gemology

Journal Name	Impact Factor	CiteScore	Launched Year	First Decision (median)	APC
Crystals crystals	2.4	4.2	2011	11.1 Days	CHF 2100
Minerals minerals	2.2	4.1	2011	18 Days	CHF 2400

16 pages, 5039 KiB

Open AccessArticle

Chemical Composition and Spectroscopic Characteristics of Heat-Treated Rubies from Madagascar, Mozambique and Tanzania

by Ling Yang, Qi Lu, Di Ma, Hairong Zheng, Ruoshui Hu, Zhuohang Shi and Binrong Qin

Crystals 2023, 13(7), 1051; https://doi.org/10.3390/cryst13071051 - 2 Jul 2023

Cited by 1 | Viewed by 4326

The chemical composition and spectra of rubies heat-treated with high temperatures (above 1200 °C) from Madagascar, Mozambique and Tanzania were analyzed by electron microprobe, LA-ICP-MS, Fourier transform infrared spectroscopy, Raman spectroscopy and UV-VIS spectroscopy. Compared with untreated rubies, the red hue of treated [...] Read more.

The chemical composition and spectra of rubies heat-treated with high temperatures (above 1200 °C) from Madagascar, Mozambique and Tanzania were analyzed by electron microprobe, LA-ICP-MS, Fourier transform infrared spectroscopy, Raman spectroscopy and UV-VIS spectroscopy. Compared with untreated rubies, the red hue of treated ruby intensifies while its blue tint diminishes, leading to increased cracks. The infrared spectra exhibit a distinct absorption peak at 3738 cm⁻¹, attributed to water because of thermal treatment. After heat treatment, the absorption intensity decreases. Ultraviolet radiation reveals an enhancement in the electron transition of Cr³⁺ and ion transition of Fe³⁺ and Fe²⁺, with a shift towards shorter wavelengths observed in the absorption bandwidth. These can be utilized to indicate the basis of ruby identification through heat treatment. Full article

(This article belongs to the Topic In-Situ Study of Mineralogy, Gemology and Progress in Gemology)
(This article belongs to the Section Mineralogical Crystallography and Biomineralization)

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12 pages, 3104 KiB

Open AccessArticle

In Situ Liquid-Phase AFM Observation of the Molecular Step Spiral Generation on the (

\bar{1}

01) Surface of Calcium Oxalate Monohydrate Crystal

by Kang Rae Cho

Crystals 2023, 13(6), 889; https://doi.org/10.3390/cryst13060889 - 28 May 2023

Cited by 1 | Viewed by 1960

Abstract

Calcium oxalate monohydrate (COM) crystal is the major crystalline component of human kidney stones. Its growth event at the nanometer and micrometer scales, i.e., the growth of the COM molecular steps generated from the dislocation outcrop on the crystal surface and its inhibition [...] Read more.

Calcium oxalate monohydrate (COM) crystal is the major crystalline component of human kidney stones. Its growth event at the nanometer and micrometer scales, i.e., the growth of the COM molecular steps generated from the dislocation outcrop on the crystal surface and its inhibition by associated acidic organic molecules such as citrate, is now well understood by studies conducted using in situ liquid-phase atomic force microscopy (AFM). Yet, the detailed assessment of the evolution of the COM molecular steps at the dislocation outcrop has been poorly conducted. Herein, in situ liquid-phase AFM was used to primarily investigate how those COM molecular steps are generated on a COM broadest crystal surface (

\bar{1}

01) and influenced by a model acidic peptide, L-aspartic acid 6mer (L-Asp₆) adsorbed onto the emerging steps and terraces on the surface. Like many other mineral crystals, a segment of the pseudo-triangle-shaped step spiral, in the process of its birth from the dislocation outcrop, starts to move after reaching the critical step length. When the budding step spiral got adsorption of L-Asp₆ to it, it appeared rather with ellipse-like hexagonal morphology—which is reflected in the bulk crystal morphology—implying changes in orientation-dependent step edge energy and much-delayed spiral generation time. Full article

(This article belongs to the Topic In-Situ Study of Mineralogy, Gemology and Progress in Gemology)
(This article belongs to the Section Mineralogical Crystallography and Biomineralization)

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17 pages, 6301 KiB

Open AccessArticle

Gemology, Mineralogy, and Spectroscopy of Gem-Quality Diopside from Pakistan and Russia: New Insights for the Chromogenic Mechanism and Possible Origin

by Zixuan Wang, Xiaoqing He, Bo Xu and Jing Ren

Crystals 2023, 13(5), 727; https://doi.org/10.3390/cryst13050727 - 25 Apr 2023

Viewed by 2602

Abstract

Green diopside is currently popular in the jewelry market due to its attractive color and excellent transparency. Gem-quality diopsides are mainly sourced from Pakistan, Italy, Russia, and other places. The color, geographic origin, and formation mechanism are the main factors affecting the value [...] Read more.

Green diopside is currently popular in the jewelry market due to its attractive color and excellent transparency. Gem-quality diopsides are mainly sourced from Pakistan, Italy, Russia, and other places. The color, geographic origin, and formation mechanism are the main factors affecting the value of gemstones, which can be determined by examining their gemology and composition characteristics. This study systematically characterizes the standard gemology of green diopsides from Pakistan and Russia and compares them with the blue diopsides produced within the skarn process and the diopsides from the nearby region in Russia from previous studies by gemological microscopy, spectral testing (infrared, Raman and ultraviolet-visible spectroscopy), and chemical analyses (electron probe and laser ablation inductively coupled plasma mass spectrometry). The results show that the spectral characteristics and phase composition of the green diopside samples from Pakistan and Russia have excellent uniformity and similarity. The high Cr, Fe, V, and Ni contents are the reasons why they appear as green. Meanwhile, the elemental characteristics of the diopside are effective tools for distinguishing different origins of different diopsides. The Russian green diopsides have higher contents of Sr, Sc, Zr, and rare earth elements (REE), indicating that they are related to alkaline ultrabasic rocks, and the source of the diopside sample from Pakistan is metamorphic rock. Full article

(This article belongs to the Topic In-Situ Study of Mineralogy, Gemology and Progress in Gemology)
(This article belongs to the Section Mineralogical Crystallography and Biomineralization)

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18 pages, 6148 KiB

Open AccessArticle

Gemological and Chemical Characterization of Varicolored Gem-Grade Spinel from Mogok, Myanmar

by Yi Zhao, Bo Xu, Zheyi Zhao, Qian Xu and Zhaoyi Li

Crystals 2023, 13(3), 447; https://doi.org/10.3390/cryst13030447 - 4 Mar 2023

Cited by 2 | Viewed by 2824

Abstract

Spinel is a precious gem with a long history, but people are far less familiar with it. Previous studies on Mogok spinel from Myanmar focused on inclusion analysis, chromogenic mechanism with a single-color gemstone and heat treatment, whereas systematic studies on varicolored gem-grade [...] Read more.

Spinel is a precious gem with a long history, but people are far less familiar with it. Previous studies on Mogok spinel from Myanmar focused on inclusion analysis, chromogenic mechanism with a single-color gemstone and heat treatment, whereas systematic studies on varicolored gem-grade spinel are lacking. In this study, the gemological and geochemical analysis of four colors of spinel samples from Mogok were carried out for basic gemology, inclusion morphology and identification, spectroscopy and geochemistry. The aim was to explore the occupation of elements of spinels in the crystal structure, as well as the chromogenic mechanism of varicolored spinels and the geological and geodynamic conditions of the formation. Mogok spinel samples are characterized by octahedral negative crystals filled with calcite and chondrodite inclusions, indicating that they are derived from a marble metamorphic-type deposit. The spinel samples of four colors are magnesia–alumina spinel (MgAl₂O₄). The contents of V and Cr in Mogok spinel are generally high, with a significant high content of Zn being the most characteristic, and trace elements vary greatly. The infrared spectra of spinel samples in different colors are basically similar. According to the UV–Vis spectrum, pink and red samples are mainly colored by Cr and/or V, whereas orange samples are mainly colored by V. Two wide absorption bands in the range 300~600 nm are mainly attributed to the spin-allowed transition and spin-forbidden transition of Cr³⁺ and/or V³⁺. The purple samples are mainly colored by Fe and the UV–Vis spectrum is mainly attributed to the spin-forbidden transition of ^TFe²⁺. This study is a favorable supplement to the research on Mogok spinels of various colors from multiple perspectives. Full article

(This article belongs to the Topic In-Situ Study of Mineralogy, Gemology and Progress in Gemology)
(This article belongs to the Section Mineralogical Crystallography and Biomineralization)

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13 pages, 3763 KiB

Open AccessArticle

Study on the Chromogenic Mechanism of Violet-Red to Orange-Red Spinel

by Yang Du and Ying Guo

Crystals 2023, 13(2), 339; https://doi.org/10.3390/cryst13020339 - 16 Feb 2023

Cited by 2 | Viewed by 2376

Abstract

In this paper, the chemical composition and spectroscopy of 38 violet-red to orange-red spinel samples were analyzed by energy dispersive X-ray fluorescence spectrometer and UV-visible spectrophotometer, based on CIE LAB color space, to explore the effects of different chromogenic ions on spinel color [...] Read more.

In this paper, the chemical composition and spectroscopy of 38 violet-red to orange-red spinel samples were analyzed by energy dispersive X-ray fluorescence spectrometer and UV-visible spectrophotometer, based on CIE LAB color space, to explore the effects of different chromogenic ions on spinel color transition. The results show that the chroma C* is mainly controlled by the variation of color coordinates a*, and the hue angle h° is mainly controlled by the variation of color coordinates b*. Spinel can be divided into iron-bearing spinel and chromium–vanadium-bearing spinel according to their chromogenic elements, where Fe is mostly present in the form of Fe²⁺, which is mainly replaced with Mg²⁺ in tetrahedral voids, while Cr³⁺ and V³⁺ are mainly replaced with Al³⁺ in octahedral voids, and the level of Al content indicates the degree of isomorphism in spinel. The lightness L* of spinel decreases with increasing Cr content, and the hue h° decreases with increasing Fe and increases with increasing V content. Full article

(This article belongs to the Topic In-Situ Study of Mineralogy, Gemology and Progress in Gemology)
(This article belongs to the Section Mineralogical Crystallography and Biomineralization)

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13 pages, 4305 KiB

Open AccessArticle

Genesis of the Body Color of Brazilian Gem-Quality Yellow-Green Opal

by Huiyu Lv and Ying Guo

Crystals 2023, 13(2), 316; https://doi.org/10.3390/cryst13020316 - 14 Feb 2023

Cited by 4 | Viewed by 2081

Abstract

The chromaticity characterization and influencing factors of the body color of 28 yellow-green opals were studied through Fourier transform infrared spectrum (FTIR), energy-dispersive X-ray fluorescence spectroscopy (ED-XRF), ultraviolet-visible spectroscopy (UV-vis) and X-Rite SP62 spectrophotometer. It was found that the hue h° and the [...] Read more.

The chromaticity characterization and influencing factors of the body color of 28 yellow-green opals were studied through Fourier transform infrared spectrum (FTIR), energy-dispersive X-ray fluorescence spectroscopy (ED-XRF), ultraviolet-visible spectroscopy (UV-vis) and X-Rite SP62 spectrophotometer. It was found that the hue h° and the iron content of the yellow-green opal were highly negatively correlated, the chroma C* and the sum of nickel and iron content were significantly positively correlated, and the lightness L* was significantly negatively correlated with the chromium content. The body color of light green opal is mainly caused by nickel. The iron content will make the color yellow, and the chromium content will darken the green. With the increase of Fe content, the lowest absorption value of UV-vis absorption at 500–650 nm moves towards the long wave direction, and the hue h° decreases. With the increase of the total content of Ni and Fe, the 650 nm absorption peak area and the chroma C* increase. Under CIE D65 standard light source and N9.5 Munsell neutral background, using K-Means clustering method, 28 yellow-green opal body colors were divided into three grades: (1) Fancy Intense, (2) Fancy Deep and (3) Fancy. Full article

(This article belongs to the Topic In-Situ Study of Mineralogy, Gemology and Progress in Gemology)
(This article belongs to the Section Mineralogical Crystallography and Biomineralization)

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25 pages, 6593 KiB

Open AccessArticle

Petrogenesis of Chatoyant Green Nephrite from Serpentinite-Related Deposits, Ospinsk, Russia: Insights from Mineralogy and Geochemistry

by Weishi He, Feng Bai, Chen Zhao, Hongting Qu and Xuemei Li

Crystals 2023, 13(2), 252; https://doi.org/10.3390/cryst13020252 - 1 Feb 2023

Cited by 3 | Viewed by 3606

Abstract

Ospinsk is an area in Russia well-known for mining the highest quality green nephrite in the world. However, the chatoyant green nephrite found here has not been studied to date. This study explores the mineralogy, geochemistry, and petrogenesis of chatoyant green nephrite collected [...] Read more.

Ospinsk is an area in Russia well-known for mining the highest quality green nephrite in the world. However, the chatoyant green nephrite found here has not been studied to date. This study explores the mineralogy, geochemistry, and petrogenesis of chatoyant green nephrite collected from Ospinsk using polarizing microscope back-scattered electron images, scanning electron microscopy, Fourier transform infrared spectrometry, laser Raman spectroscopy, electron microprobe analysis, and laser ablation inductively coupled plasma mass spectrometry, and compares them with S-type green nephrite from other regions of the world. Tremolite is the main mineral constituent, and chromite, chlorite, graphite, and magnetite are accessory minerals in the samples. The chatoyant green nephrite from Ospinsk is serpentinite-related green nephrite. The Ti content of the chatoyant green nephrite from Ospinsk is significantly higher than that of green nephrite from other places. The chatoyant green nephrite deposit in Ospinsk is a contact metasomatic deposit related to ultramafic rocks. The ultramafic rocks first altered to serpentinite and later converted to tremolite after repeated thermal contact-based metasomatism. During the metasomatism of serpentinite into green nephrite, unilateral, compressive, and shear stresses caused by obduction forced directional growth of tremolite, resulting in chatoyancy. Full article

(This article belongs to the Topic In-Situ Study of Mineralogy, Gemology and Progress in Gemology)
(This article belongs to the Section Mineralogical Crystallography and Biomineralization)

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17 pages, 11875 KiB

Open AccessArticle

Gemological and Mineralogical Characteristics of Emerald from Ethiopia

by Zixuan Huang, Geng Li, Liqun Weng and Meilun Zhang

Crystals 2023, 13(2), 233; https://doi.org/10.3390/cryst13020233 - 29 Jan 2023

Cited by 9 | Viewed by 5083

Abstract

Ethiopia has been gaining attention in recent years as an emerging source of high-quality emerald. Ethiopian emerald samples with different colors ranging from dark green to light green were selected to study the gemological properties, chemical composition, and spectral characteristics. The Ethiopian emeralds [...] Read more.

Ethiopia has been gaining attention in recent years as an emerging source of high-quality emerald. Ethiopian emerald samples with different colors ranging from dark green to light green were selected to study the gemological properties, chemical composition, and spectral characteristics. The Ethiopian emeralds were examined using conventional gemological instruments, including X-ray fluorescence spectrometry, LA-ICP-MS, UV/Vis/NIR, infrared spectrometry, and Raman spectrometry, providing a wealth of data and research information related to Ethiopian emeralds. The EDXRF results show that the chemical composition of Ethiopian emeralds is distinctly regional compared to emeralds of Colombian origin, being low in Cr, low in V, and high in Fe. LA-ICP-MS results demonstrate consistent results for Cr (734.34 to 1644.3 ppmw), V (89.61 to 106.61 ppmw), and Fe (4468.04 to 5022.3 ppmw) based on the chemical composition analysis by EDXRF. In addition, the LA-ICP-MS assay revealed that the combination of alkali metals (Li, Na, K, Rb, and Cs) and some trace elements (Sc, V, Cr, and Fe) could distinguish the Ethiopian emeralds from those from other regions. The Ethiopian emerald had absorption of Fe²⁺, Cr³⁺, V³⁺, and Fe³⁺, and the typical absorption intensity of Fe²⁺ (around 850 nm) was higher than that of Fe³⁺ (around 371 nm) in the UV/Vis/NIR spectra. The infrared spectrum of samples indicated that the absorption of type II H₂O was higher than type I H₂O in the emeralds from Ethiopia, which is consistent with the high content of alkali metals detected by LA-ICP-MS that would lead to an increase in the content of type II H₂O. The Raman spectra showed absorption at 410 cm⁻¹, 569 cm⁻¹, 687 cm⁻¹, 995 cm⁻¹, and 1067 cm⁻¹, with an emerald species recognition pattern. The gas–liquid two-phase inclusions of the emerald in this area were mainly CO₂ and H₂O, and the samples contained typical dark inclusions of magnesium-rich biotite sheets that revealed the tectonic-magmatic-related geological environment in this region. Full article

(This article belongs to the Topic In-Situ Study of Mineralogy, Gemology and Progress in Gemology)
(This article belongs to the Section Mineralogical Crystallography and Biomineralization)

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11 pages, 2219 KiB

Open AccessArticle

Mineralogical Characteristics Study of Calcite from the Fujian Province, China

by Zhe-Yi Zhao, Yu-Tao Lin, Yi Zhao and Bo Xu

Crystals 2023, 13(1), 51; https://doi.org/10.3390/cryst13010051 - 27 Dec 2022

Cited by 1 | Viewed by 2221

Abstract

With mineral in situ testing technology and ore deposit geochemistry development, calcite has become a hot topic in studying carbonate minerals. Four large-grain calcite crystals from Fujian, China, were used for a detailed study. This study provides a comprehensive data set through mineralogical [...] Read more.

With mineral in situ testing technology and ore deposit geochemistry development, calcite has become a hot topic in studying carbonate minerals. Four large-grain calcite crystals from Fujian, China, were used for a detailed study. This study provides a comprehensive data set through mineralogical standard properties and spectral characteristics, including Fourier transform infrared, X-ray fluorescence spectrum, and Raman spectroscopy. Major elements were analyzed using X-ray fluorescence (XRF) and Micro-XRF. A high-resolution gas-source stable isotope ratio mass spectrometer was used to test C-O isotope characteristics. The four samples’ spectral characteristics and phase composition show excellent uniformity, all with the same characteristic peaks, indicating that they are pure calcite without other impurity minerals. C-O isotope characteristics indicate that Fujian calcite has mantle genetic characteristics, which may be affected by marine carbonate dissolution or sedimentary rock contamination. The variation of Fe and Mn contents may indicate that the four samples formed at different metallogenic stages. Full article

(This article belongs to the Topic In-Situ Study of Mineralogy, Gemology and Progress in Gemology)
(This article belongs to the Section Mineralogical Crystallography and Biomineralization)

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16 pages, 4627 KiB

Open AccessArticle

Evaluating the Effect of ¹⁸O Incorporation on the Vibrational Spectra of Vaterite and Calcite

by Helen E. King, Aleksandar Živković and Nora H. de Leeuw

Crystals 2023, 13(1), 48; https://doi.org/10.3390/cryst13010048 - 27 Dec 2022

Viewed by 2181

Abstract

Calcium carbonates are critical in biomineralization processes and as functional materials. For many applications, isotope enrichment in these materials allows researchers to monitor reaction pathways and retrace environmental signatures. When using vibrational spectroscopy, isotopic composition is currently derived by summing the concentration of [...] Read more.

Calcium carbonates are critical in biomineralization processes and as functional materials. For many applications, isotope enrichment in these materials allows researchers to monitor reaction pathways and retrace environmental signatures. When using vibrational spectroscopy, isotopic composition is currently derived by summing the concentration of each isotopologue, assumed to be directly obtainable from the band intensity, divided by the content of the isotope within the different isotopologues (e.g., C¹⁶O₃, C¹⁶O₂¹⁸O, C¹⁶O¹⁸O₂ and C¹⁸O₃). However, this approach relies on the assumption that each isotopologue band has an equivalent intensity when present at the same concentration within the crystal structure. Here, using a joint experimental and theoretical approach we test the spectral behavior of the O-isotopologues by examining the effect of a key isotopic tracer, ¹⁸O, on the vibrational spectra of the calcium carbonate phases calcite and vaterite. We demonstrate that isotopic substitution changes both band positions and band intensities to different extents, depending on the vibrational spectroscopy method used and the bands examined. For calcite, the υ₁ symmetrical stretching Raman-active bands related to individual isotopologues are found to have very similar intensities and are not affected by changes in isotopologue distribution within the material. Fitting these bands resulted in a consistent underestimation of the isotopic enrichment of only 1%, thus they are expected to be useful for estimating ¹⁸O-enrichment extent in future experimental work. In contrast, vaterite vibrational bands change more extensively and thus cannot be used directly to determine the ¹⁸O concentration within the material. These results are expected to contribute to a deeper und less ambiguous understanding of evaluating isotopic enrichment effects in the vibrational spectra of calcium carbonates. Full article

(This article belongs to the Topic In-Situ Study of Mineralogy, Gemology and Progress in Gemology)
(This article belongs to the Section Mineralogical Crystallography and Biomineralization)

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