Cs-dominant polylithionite in the Koktokay#3 pegmatite,Altai, NW China: in situ micro-characterization and implication for the storage of radioactive cesium |
| |
Authors: | R C Wang H Hu A C Zhang F Fontan Ph de Parseval S Y Jiang |
| |
Institution: | (1) State Key Lab for Mineral Deposits Research, Department of Earth Sciences, Nanjing University, Nanjing, 210093, China;(2) LMTG-UMR 5563, Université Paul Sabatier, 14 avenue Edouard Belin, Toulouse, 31400, France |
| |
Abstract: | Except forming two Cs-rich minerals like pollucite and londonite, cesium generally occurs in trace amounts in potassium-bearing
minerals owing to its very low Clarke value and large ionic radius. However, in the Koktokay#3 pegmatite (Altai, NW China),
lepidolite is extremely enriched in cesium (typically 21–26 wt% Cs2O). Cs-enriched lepidolite is restricted to the inner of the pegmatite, where four types of occurrence are characterized by
using in situ techniques (EMP: electron microprobe, micro-XRD: micro-area X-ray diffractometer and Raman probe: micro-area
Raman spectrometer) as: (1) outer zones on Cs-poor lepidolite cores; (2) fine overgrowths on muscovite veinlets; (3) veinlets
in Cs-poor lepidolite and (4) veinlets in elbaite. There is an inverse correlation between K and Cs and in terms of VIAl versus Cs/(K+Cs), the Cs-dominant micas are an analog of the Li-rich mica polylithionite. Micro-XRD patterns and micro-Raman
spectra indicate that Cs-dominant polylithionite structurally corresponds to minerals of the lepidolite series. According
to its distribution and compositional characteristics, the Cs-dominant polylithionite seems to have formed at the magmatic
to hydrothermal transition stage of pegmatitic magma evolution as a result of marginal replacement of early-formed lepidolite
by Cs-rich fluids. Alternatively, it may have formed through direct precipitation from Cs-rich fluids. The results of the
present study have important implications for the storage of nuclear waste in that Li mica such as polylithionite is a good
candidate for immobilizing high-level radioactive cesium waste. |
| |
Keywords: | |
本文献已被 SpringerLink 等数据库收录! |
|