Preliminary Investigation on the Occurrence of Reddish Brown Colour in Zircon from Kolonna, Sri Lanka

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dc.contributor.authorRifkhan, M.N.M.
dc.contributor.authorWewegedara, W.G.C.N.
dc.contributor.authorJayasinghe, R.M.N.P.K.
dc.contributor.authorDharmaratne, T.S.
dc.contributor.authorMalaviarachchi, M.A.S.P.K.
dc.contributor.authorRohana, C.
dc.date.accessioned2021-02-25T06:38:58Z
dc.date.available2021-02-25T06:38:58Z
dc.date.issued2020
dc.description.abstractSri Lanka is famous for various types of gem minerals. From among these minerals, gemquality zircon is found in both primary and secondary deposits. Kolonna is a location where zircon is found in primary deposits with a reddish-brown colour. The main objective of this study was to investigate the occurrence of reddish-brown colour in zircon from Kolonna area. Although many factors could cause the colour of gem minerals, the colour of zircons is known to be produced by trace elements (transition metals, lanthanides, actinides, and REEs), radiation damage (radiation-induced color centers) and charge transfer. Five randomly selected reddish-brown zircon samples were selected for this study. All samples were translucent, highly fractured, sub-adamantine, and with euhedral to subhedral crystal form. Samples were analyzed with EDXRF, UV-Vis Spectrophotometer, and FTIR methods. The UV-Vis spectrum of these samples showed an increase in absorption towards the UV region and declines towards the NIR region with a shoulder at around 500 nm. This can be identified as a structurally defected colour center that may occur due to the radiation damage caused by radioactive elements such as U and Th. This was further confirmed by the U4+ peak at 654 and 690 nm. The U5+ peak at 6663 cm-1 in the FTIR spectrum further confirmed the presence of U in samples. This was confirmed by the EDXRF analyses that showed a trace amount of radioactive elements. The average weight percentage of U and Th were 0.06 and 0.02, respectively. It was also noted an occurrence of an OH- group indicated at 3196 cm-1 on FTIR spectra. This may be probably due to slight radiation damage caused by radioactive elements in zircon samples. This study revealed the presence of U which accounts for structural defects that form colour centers in reddish-brown zircon from the Kolonna region. Keywords: Absorption, Colour center, Cause of color, Zircon, Radiationen_US
dc.identifier.isbn9789550481293
dc.identifier.urihttp://www.erepo.lib.uwu.ac.lk/bitstream/handle/123456789/6098/proceeding_oct_08-460.pdf?sequence=1&isAllowed=y
dc.language.isoenen_US
dc.publisherUva Wellassa University of Sri Lankaen_US
dc.relation.ispartofseries;International Research Conference
dc.subjectMaterials Sciencesen_US
dc.subjectMineral Sciencesen_US
dc.subjectGem Fielden_US
dc.subjectGemstonesen_US
dc.titlePreliminary Investigation on the Occurrence of Reddish Brown Colour in Zircon from Kolonna, Sri Lankaen_US
dc.title.alternativeInternational Research Conference 2020en_US
dc.typeOtheren_US
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