LUMINESCENCE OF QUARTZ-CHALCEDONY FORMATIONS OF KUZBASS AND ITS RELATION TO GEOCHEMICAL CHARACTERISTICS OF AGATES

Abstract

The relevance of the research is caused by quartz-chalcedony formations of Kuzbass being a potential gem and ornamental stones and by existing uncertainties related to agates formation issues. At the same time Kuzbass agates require more profound mineralogical study. The aim of the research is to study such luminescence features of quartz-chalcedony formations of South Kuzbass magmatic area as spectral composition and its variations in different zones and layers of studied samples; variations of certain luminescence centers behavior; the way geochemical features influence luminescence spectra of studied minerals. The objects of the research are quartz-chalcedony formations of South Kuzbass magmatic area including placer-type Klyuchi occurrence (Krapivinsk rayon), agate-containing amygdaloidal basalts of Tersyuk occurrence (Novokuznetsk rayon), agate-containing amygdaloidal basalts of Saltymakovskiy ridge occurences (Krapivinsk rayon) in Kemerovo region. The methods of the research are X-ray diffraction analysis, X-ray luminescence analysis and inductively coupled plasma mass spectrometry. Results. Mineralogical composition was studied with use of X-ray diffraction analysis. The most abundant minerals are quartz and chalcedony (with quartz prevailing). Chalcedony highest content was observed in amygdules with concentrical zoning. Among other minerals there are cristobalite, dolomite, calcite, zeolites. Contents of intrinsic and extrinsic defects of different nature taking places in minerals structure were studied by means of X-ray luminescence analysis. Luminescence centers distribution in different layers of Tersyuk agates may be an evidence that oxidative conditions in outer zone changed to reductive conditions in inner zones. This change was also confirmed by geochemical study results. X-ray luminescence spectra of different layers of Saltymakovskiy ridge onyxes are identic to each other. This means that mineral formation conditions were rather stable. It was concluded that there was oxidative environment in amygdules of Saltymakovskiy ridge and Klyuchi occurrences while in amygdules of Tersyuk occurrence there was reductive environment mostly.

Keywords

• quartz
• chalcedony
• agate
• onyx
• south kuzbass magmatic area
• luminescence
• structure defects