Gem Topaz from the Schneckenstein Crag, Saxony, Germany: Mineralogical Characterization and Luminescence

Zeug, Manuel; Nasdala, Lutz; N., Chutimun Chanmuang; Hauzenberger, Christoph

doi:10.5741/gems.58.1.2

Cited by 3 publications

(2 citation statements)

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“…For example, Mn 2+ is the most popular luminescence agent in nature, and Fe 3+ is a commonly known quenchant [20]. The red fluorescence in minerals, such as ruby and spinel, is mainly caused by Cr 3+ [21,22]. Therefore, in this study, the contents of the common transition metal elements (Cr, Ti, V, Mn, and Fe) are compared with the fluorescence color and intensity of taaffeites to analyze their correlation.…”

Section: Fluorescence Spectroscopymentioning

confidence: 99%

Gemological and Luminescence Characteristics of Taaffeites from Mogok, Myanmar

Lin

Zhang

et al. 2023

Minerals

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Taaffeite is a rare gem that has been found in different localities such as Tanzania, Sri Lanka, China, and Mogok, Myanmar. In this study, thirty-two taaffeite samples from Mogok, Myanmar, were investigated by conventional gemological testing, laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), Raman spectrometry, and fluorescence spectrometry. Through microscopic observations, various types of inclusions were observed in these taaffeites, including irregular inclusions, orange and brown intrusions, black dotted and flake inclusions, healed fissures, tubular inclusions, fingerprint inclusions, and multi-phase inclusions. The Raman spectra demonstrated that the inclusions were mainly calcite, forsterite, celestite, graphite, dolomite, and transparent tubular or columnar inclusions filled with CO2. In previous studies, taaffeite showed inert or chalky fluorescence under long-wave ultraviolet (LWUV) light and inert fluorescence under short-wave ultraviolet (SWUV) light. In this study, the taaffeite samples revealed different fluorescence phenomena under ultraviolet light. Thirty-two taaffeite samples were classified into four categories according to their fluorescence under LWUV: orange-red, pink, green, and blue-white fluorescence. Under SWUV, all samples presented inert to bright pink fluorescence. Two-dimensional fluorescence spectra were obtained through a fluorescence spectrometer. For the samples with orange-red and pink fluorescence under LWUV, two-dimensional fluorescence spectra showed that peaks at 686 nm and 690 nm (in the red region) were strong. For the samples with green and blue-white fluorescence under LWUV, peaks at 439 nm and 464 nm (in the blue region) were strong, peaks at 507–515 nm (in the green region) were relatively weak, and peaks at 686 and 690 nm (in the red region) were very weak. Combined with the data from LA-ICP-MS, it is speculated that Cr3+ was responsible for samples having orange-red and pink fluorescence, that Mn2+ was responsible for samples having green fluorescence, and that Fe inhibited the generation of fluorescence.

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Section: Fluorescence Spectroscopymentioning

confidence: 99%

Gemological and Luminescence Characteristics of Taaffeites from Mogok, Myanmar

Lin

Zhang

et al. 2023

Minerals

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“…The luminescence of Cr 3+ in minerals has been well investigated, where studied minerals include corundum, spinel, topaz, emerald, etc. [5][6][7][8]. Mn 2+ is also a well-known activator in many minerals.…”

Section: Introductionmentioning

confidence: 99%

Luminescence Characteristics of Green Grossular Garnets

et al. 2023

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Some light green grossular garnets exhibit orange-red luminescence under long-wave and short-wave ultraviolet light. To characterize their luminescence behavior, we studied seven grossular garnets with typical colors ranging from light yellowish-green to intense green by using photoluminescence (PL), ultraviolet–visible (UV–Vis) spectroscopy, electron paramagnetic resonance (EPR), Electron Probe Microanalysis (EPMA) and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). In the PL spectra of these grossular garnets samples, a broad band exists at about 589 nm and three sharp peaks appear at 697, 702 and 716 nm. The three-dimensional fluorescence spectra reveal two luminescence emissions. They are (1) a broad band near 600 nm; and (2) a series of sharp peaks centered at 697, 702 and 716 nm. In the UV–Vis spectra, two prominent asymmetrical absorption bands near 430 and 605 nm are related to Cr3+ or Cr3+/V3+, and minor absorption peaks at 408 and 419/420 nm are related to Mn2+. EMPA and LA-ICP-MS analysis confirmed the existence of trace elements Ti, V, Cr and Mn. Furthermore, the EPR spectrum excluded the existence of V2+ and V4+ and confirmed the existence of Mn2+, Cr3+ and Fe3+. Regarding V, an interesting phenomenon was reported in which the intensity of luminescence could be suppressed in grossular garnets with higher concentrations of V. These results imply that chromium and manganese are the luminescence activators in grossular garnets, and vanadium is a powerful quencher.

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