Luminescence and micro-Raman investigations on inclusions of unusual habit in chrysoprase from Turkey

Ayvackli M.; Garcia-Guinea J.; Jorge A.; Akaln I.; Kotan Z.; Can N.

Luminescence and micro-Raman investigations on inclusions of unusual habit in chrysoprase from Turkey

Date

2012

Authors

Abstract

Chemical analyses performed on chrysoprase from Turkey have shown many trace elements as well as rare earth impurities. Quantitative chemical analyses of inclusions in minerals can improve our understanding of the chemistry of surface. The environmental scanning electron microscope (ESEM) with an attached X-ray energy dispersive system (EDS) is capable of producing rapid and accurate major element chemical analyses of individual inclusions in crystals larger than about 30 μm in diameter. The samples were examined with lifetime-resolved and spatially-resolved cathodoluminescence (CL), and inductively coupled plasma-atomic emission spectrometry (ICP-AES). Spatially resolved CL results at room temperature were recorded for two different areas. Bulk area displays with low CL emission and pores contain iron phases such as chromite, hematite and anatase which cause the green color. For the raw data in the lifetime resolved CL spectrum, at least three broad emission bands were detected in a yellow band of the highest intensity at about 550 nm, a weaker orange band at about 650 nm, and a red band at 720 nm. It is assumed that there are links between the CL emissions and the presence of some transition metal and REE elements, but it is obvious that all trace elements do not play a direct role. Micro-Raman measurements were performed on chrysoprase and these showed a characteristic intensive Raman band peaked at 464 cm -1 which can be inferred to ν 2 doubly symmetric bending mode of [SiO 4/M] centers. Raman spectrum of all inclusions found in the material are also given and discussed in detail. © 2012 Elsevier B.V.