Fluorescence survey of Turkish borate minerals: comparative measurements of fluorescence spectra of the most important borate mineral species, Turkey


Helvaci C., YÜCEL ÖZTÜRK Y., Emmermann A.

NEUES JAHRBUCH FUR MINERALOGIE-ABHANDLUNGEN, vol.194, no.1, pp.1-17, 2017 (SCI-Expanded) identifier identifier identifier

  • Publication Type: Article / Article
  • Volume: 194 Issue: 1
  • Publication Date: 2017
  • Doi Number: 10.1127/njma/2016/0016
  • Journal Name: NEUES JAHRBUCH FUR MINERALOGIE-ABHANDLUNGEN
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Page Numbers: pp.1-17
  • Keywords: Fluorescence spectra, borate minerals, Turkey, DEPOSITS, COLEMANITE, ANATOLIA, RAMAN, LAKE
  • Dokuz Eylül University Affiliated: Yes

Abstract

The dominant and most important borate minerals, from a worldwide commercial standpoint, are borax, ulexite, and colemanite. They are produced in a limited number of countries, essentially by Turkey and the United States. The main borate districts of Turkey are Bigadie, Kestelek, Sultaneayir, Emet, and Kirka. These borate deposits of western Turkey are associated with extensive medium- to high-K calc-alkaline ignimbritic volcanism and a differentiated co-magmatic alkaline trachybasalttrachydacite lava suite. Ignimbritic air-fall and reworked pumiceous elastic materials are intimately associated with saline-alkaline lakes that host the borate deposits. Our aim was to compare the spectra of these different borate species and to attempt to explain the mechanisms behind these common features using steady state spectrometry. Eventually, it provided the answer to the emission spectra. We investigated the fluorescence, at room temperature of borax, ulexite, colemanite, priceite, probertite, teruggite, tunellite and howlite, using UV-LED's and a 405 nm laser. It appears that all the spectra share common features. Visual observation of the samples under ultraviolet light showed that the orange fluorescence is predominantly present in well-crystallized material. Only a very small portion of the fluorescence is due to the presence of lanthanide elements, but the high solubility in water of minerals like colemanite, borax, and ulexite may lower the concentration threshold at which these lanthanide elements become exploitable. We propose that the calcium humate complex is the main cause of the orange fluorescence seen in colemanite and other borate mineral specimens. However, the study shows that both As3+ and As5+ are present in concentrations up to 125 ppm in the colemanite specimens that were examined and may contribute to the fluorescence. Although we selected clean and pure colemanite sample for this study, arsenic present could be due to substitution in the colemanite crystal lattice structure as well as some individual arsenic minerals (e.g. realgar and orpiment) that occur rarely in the deposit.