The Different Inclusions’ Characteristics between Natural and Heat-Treated Tanzanite: Evidence from Raman Spectroscopy

In this paper, Raman spectroscopy experiments were used to distinguish the characteristics of inclusions (calcite, anatase, graphite etc.) between natural and heat-treated tanzanite. These characteristics were preliminarily divided according to their pleochroism. In natural unheated tanzanite (N5),...

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Autores principales:	Shuqi Yang, Huijuan Ye, Yingxin Liu
Formato:	article
Lenguaje:	EN
Publicado:	MDPI AG 2021
Materias:	tanzanite heat treatment Raman spectroscopy inclusions Crystallography QD901-999
Acceso en línea:	https://doaj.org/article/bd4094a477cf47928f4bd130d5f4c891
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spelling	oai:doaj.org-article:bd4094a477cf47928f4bd130d5f4c8912021-11-25T17:17:56ZThe Different Inclusions’ Characteristics between Natural and Heat-Treated Tanzanite: Evidence from Raman Spectroscopy10.3390/cryst111113022073-4352https://doaj.org/article/bd4094a477cf47928f4bd130d5f4c8912021-10-01T00:00:00Zhttps://www.mdpi.com/2073-4352/11/11/1302https://doaj.org/toc/2073-4352In this paper, Raman spectroscopy experiments were used to distinguish the characteristics of inclusions (calcite, anatase, graphite etc.) between natural and heat-treated tanzanite. These characteristics were preliminarily divided according to their pleochroism. In natural unheated tanzanite (N5), calcite inclusion is often interspersed with dolomite and has Raman shifts around 156, 283, 710, and 1087 cm<sup>−1</sup>. In other high temperature treatment samples, the baseline of calcite increased and their Raman peaks gradually shifted towards lower frequencies. Anatase inclusions in natural tanzanite (N5) have four characteristic Raman peaks around 146, 394, 514, and 641 cm<sup>−1</sup>. Because of the longer Ti-O bond and the wider bond angle distribution caused by high temperature, fewer Raman peaks were observed and the peaks’ intensities were weakened in the heat-treated T7 sample. The black graphite inclusions are often scattered or have a dotted distribution. The most obvious difference between natural and heat-treated samples is that the latter lack the characteristic 1350 cm<sup>−1</sup> Raman peak of graphite, thus representing the order and structural incompleteness of graphite. In addition, there are other inclusions in natural unheated tanzanite, such as lead-grey molybdenite with strong metallic luster, randomly scattered prehnite with white dots, orange-yellow rounded rutile, and metallic luster hematite.Shuqi YangHuijuan YeYingxin LiuMDPI AGarticletanzaniteheat treatmentRaman spectroscopyinclusionsCrystallographyQD901-999ENCrystals, Vol 11, Iss 1302, p 1302 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	tanzanite heat treatment Raman spectroscopy inclusions Crystallography QD901-999
spellingShingle	tanzanite heat treatment Raman spectroscopy inclusions Crystallography QD901-999 Shuqi Yang Huijuan Ye Yingxin Liu The Different Inclusions’ Characteristics between Natural and Heat-Treated Tanzanite: Evidence from Raman Spectroscopy
description	In this paper, Raman spectroscopy experiments were used to distinguish the characteristics of inclusions (calcite, anatase, graphite etc.) between natural and heat-treated tanzanite. These characteristics were preliminarily divided according to their pleochroism. In natural unheated tanzanite (N5), calcite inclusion is often interspersed with dolomite and has Raman shifts around 156, 283, 710, and 1087 cm<sup>−1</sup>. In other high temperature treatment samples, the baseline of calcite increased and their Raman peaks gradually shifted towards lower frequencies. Anatase inclusions in natural tanzanite (N5) have four characteristic Raman peaks around 146, 394, 514, and 641 cm<sup>−1</sup>. Because of the longer Ti-O bond and the wider bond angle distribution caused by high temperature, fewer Raman peaks were observed and the peaks’ intensities were weakened in the heat-treated T7 sample. The black graphite inclusions are often scattered or have a dotted distribution. The most obvious difference between natural and heat-treated samples is that the latter lack the characteristic 1350 cm<sup>−1</sup> Raman peak of graphite, thus representing the order and structural incompleteness of graphite. In addition, there are other inclusions in natural unheated tanzanite, such as lead-grey molybdenite with strong metallic luster, randomly scattered prehnite with white dots, orange-yellow rounded rutile, and metallic luster hematite.
format	article
author	Shuqi Yang Huijuan Ye Yingxin Liu
author_facet	Shuqi Yang Huijuan Ye Yingxin Liu
author_sort	Shuqi Yang
title	The Different Inclusions’ Characteristics between Natural and Heat-Treated Tanzanite: Evidence from Raman Spectroscopy
title_short	The Different Inclusions’ Characteristics between Natural and Heat-Treated Tanzanite: Evidence from Raman Spectroscopy
title_full	The Different Inclusions’ Characteristics between Natural and Heat-Treated Tanzanite: Evidence from Raman Spectroscopy
title_fullStr	The Different Inclusions’ Characteristics between Natural and Heat-Treated Tanzanite: Evidence from Raman Spectroscopy
title_full_unstemmed	The Different Inclusions’ Characteristics between Natural and Heat-Treated Tanzanite: Evidence from Raman Spectroscopy
title_sort	different inclusions’ characteristics between natural and heat-treated tanzanite: evidence from raman spectroscopy
publisher	MDPI AG
publishDate	2021
url	https://doaj.org/article/bd4094a477cf47928f4bd130d5f4c891
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The Different Inclusions’ Characteristics between Natural and Heat-Treated Tanzanite: Evidence from Raman Spectroscopy

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