Publication: Geology, gemmological properties and preliminary heat treatment of gem-quality zircon from the central highlands of Vietnam
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0
Issued Date
2016
Resource Type
File Type
application/pdf
ISSN
13554565
Other identifier(s)
2-s2.0-85010639094
Rights Holder(s)
Scopus
Bibliographic Citation
Journal of Gemmology. Vol 35, No.4 (2016), p.308-318
Suggested Citation
Huong L.T.-T., Vuong B.S., Thuyet N.T.M., Khoi N.N., Satitkune S., Wanthanachaisaeng B., Hofmeister W., Häger T., Hauzenberger C. Geology, gemmological properties and preliminary heat treatment of gem-quality zircon from the central highlands of Vietnam. Journal of Gemmology. Vol 35, No.4 (2016), p.308-318. doi:10.15506/JoG.2016.35.4.308 Retrieved from: https://hdl.handle.net/20.500.14740/5961
Abstract
Gem-quality brown zircon occurs in alluvial deposits derived from Neogene- Quaternary alkali basalts in the Central Highlands of Vietnam. Rough and cut samples were characterized using standard gemmological methods, chemical analysis (electron microprobe and LA-ICP-MS), and Raman, FTIR and UVVis- NIR spectroscopy. Among the internal features observed were colour zoning and various mineral inclusions, such as apatite, ilmenite, hematite and iron hydroxide. The analysed samples contained up to 1.14 wt.% HfO2 and 0.08 wt.% total REE oxides. Darker brown stones contained greater amounts of Hf than the lighter-coloured ones. Raman and FTIR spectroscopy showed that the zircon is high-type (i.e. has high crystallinity). As with the famous Ratanakiri zircon of neighbouring Cambodia, heat treatments can be applied to dark-coloured samples to lighten the coloration in an oxidizing atmosphere or induce blue colour in reducing conditions. © 2016 The Gemmological Association of Great Britain.