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Chemical Classifcation of Gem Garnets
Dissertation (MSc)--University of Pretoria, 2016.
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| Format: | Thesis |
| Language: | English |
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University of Pretoria
2016
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| _version_ | 1867613507079372800 |
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| access_status_str | Open Access |
| author2 | Merkle, R.K.W. (Roland Karl Willi), 1954- |
| author_browse | Merkle, R.K.W. (Roland Karl Willi), 1954- |
| author_facet | Merkle, R.K.W. (Roland Karl Willi), 1954- |
| collection | Thesis |
| dc_rights_str_mv | © 2016 University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. |
| description | Dissertation (MSc)--University of Pretoria, 2016. |
| format | Thesis |
| id | oai:repository.up.ac.za:2263/51329 |
| institution | University of Pretoria (South Africa) |
| language | English |
| last_indexed | 2026-06-10T12:37:14.671Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UPSpace — University of Pretoria Institutional Repository |
| publishDate | 2016 |
| publishDateRange | 2016 |
| publishDateSort | 2016 |
| publisher | University of Pretoria |
| publisherStr | University of Pretoria |
| record_format | dspace |
| source_str | UPSpace — University of Pretoria Institutional Repository |
| spelling | oai:repository.up.ac.za:2263/51329 Chemical Classifcation of Gem Garnets Merkle, R.K.W. (Roland Karl Willi), 1954- Maharaj, Deepti Gemology Chemical classification Gem garnets Garnet group minerals UCTD Natural and agricultural sciences theses SDG-09 Natural and agricultural sciences theses SDG-12 Dissertation (MSc)--University of Pretoria, 2016. Gem garnet chemistry is described using the end-members pyrope, almandine, spessartine, andradite, grossular, and uvarovite. The large variation in garnets makes classification difficult. Garnet gemstones are typically classified by means of their refractive indices, together with specific gravity. However, the range of refractive indices for gem garnets can be restrictive and unreliable in gemstone classification. Chemical classification is generally the most accurate means of classification and was used in this thesis by means of a portable XRF for the non-destructive chemical analyses of 1513 garnet gemstones. Colour, refractive index and magnetic susceptibility were also determined. The garnets were divided into two species: ugrandite (uvarovite, grossular and andradite) and pyralspite (pyrope, spessartine and almandine). The chemistry of the pyralspite species was very diverse with a large range in end-member proportions producing extensive solid solutions between end-members. A diverse range in colour, refractive index, and magnetic susceptibility was also observed in the pyralspite species. However, no distinction based on refractive index and magnetic susceptibility could be made in the pyralspite species. Distinctive chemistries were observed in the ugrandite species, which correlates with the magnetic susceptibility and refractive index. Colour was the exception as no relationship between colour and chemistry was observed. The samples with unusual compositions were reported such as pyrope-andradite, spessartine-grossular, and almandine-grossular. This study concluded that refractive index, magnetic susceptibility and colour should not be used in isolation because this can lead to misinterpretation. Rather, analytical techniques, if available, should be used. bs2026 Geology Unrestricted SDG-09: Industry, innovation and infrastructure SDG-12: Responsible consumption and production 2016-02-10T13:45:21Z 2016-02-10T13:45:21Z 2016-04-05 2016 Dissertation Maharaj, D 2016, Chemical Classification of Gem Garnets, MSc dissertation, University of Pretoria, Pretoria, viewed yymmdd <http://hdl.handle.net/2263/51329> A2016 http://hdl.handle.net/2263/51329 en © 2016 University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. application/pdf University of Pretoria |
| spellingShingle | Gemology Chemical classification Gem garnets Garnet group minerals UCTD Natural and agricultural sciences theses SDG-09 Natural and agricultural sciences theses SDG-12 Chemical Classifcation of Gem Garnets |
| title | Chemical Classifcation of Gem Garnets |
| title_full | Chemical Classifcation of Gem Garnets |
| title_fullStr | Chemical Classifcation of Gem Garnets |
| title_full_unstemmed | Chemical Classifcation of Gem Garnets |
| title_short | Chemical Classifcation of Gem Garnets |
| title_sort | chemical classifcation of gem garnets |
| topic | Gemology Chemical classification Gem garnets Garnet group minerals UCTD Natural and agricultural sciences theses SDG-09 Natural and agricultural sciences theses SDG-12 |
| url | http://hdl.handle.net/2263/51329 |