PDF Publication Title:
Text from PDF Page: 286
250 Handbook on the Physics and Chemistry of Rare Earths FIG. 50 Plots of SiO2 vs REE2O3 contents (A) and LREE/HREE ratio (B) in apatites in IOA deposits and prospects. LREEs: La-Eu, HREEs: Y, Gd-Lu, REE2O3: Y, La-Lu. Data from Bonyadi et al., 2011; Edfelt et al., 2005; Halpin et al., 2010; Harlov et al., 2002; Hoshino et al., 2015; Hoshino et al., submitted; Jami et al., 2007). From Hoshino, M., Watanabe, Y., Kon, Y. Contribution of apatite XE “apatite” to the crystal growth of allanite in an iron-oxide- apatite (IOA) prospect, Benjamin River, Canada. Resour. Geol. (submitted). is below detection limit by EMPA. Benjamin River apatite crystals contain high SiO2, and REE incorporation into them are accomplished only by britho- lite substitution, but their Th and U contents are low (Table 16 and Fig. 50). BSE images of Benjamin River apatite crystals show bright, dark, porous zones (Fig. 51), and the last contain very low REE2O3 and SiO2 contents com- pared to the first two (Table 16). Allanite always occurs near porous zone of apatite, which suggests that allanite grains characteristically occurring in apa- tite–augite–magnetite ore formed by REEs leached from apatite by hydrother- mal fluid in hydrothermal stages. Similar crystallization of REE minerals by remobilization of REEs from apatite are observed in many other IOA depos- its, but in monazite form in most of IOA deposits like Kiruna, not in allanite (Hoshino et al., submitted). The stability of allanite and monazite appears to be related to the activity of Ca: allanite forms at high Ca activity, whereas monazite precipitates at lower Ca activity (eg, Casillas et al., 1995; Lee and Dodge, 1964; Snetsinger, 1967). Dominant occurrence of augite at Benjamin River IOA prospect may have been responsible for allanite, but not monazite precipitation, because of high Ca activity in the hydrothermal fluid (Hoshino et al., submitted). Interestingly, hydrothermal monazite and allanite from IOA deposit, which were crystallized by embracing REE leached from apatite, have very low ThO2 (<0.60 wt.%: Bonyadi et al., 2011; Harlov et al., 2002; Hoshino et al., submitted), although igneous monazite and allanite generally include high ThO2 contents (Hoshino et al., 2006, 2012b). These findings sug- gest that IOA deposits have big advantage as research objects for future REE resources.PDF Image | HANDBOOK ON THE PHYSICS AND CHEMISTRY OF RARE EARTHS
PDF Search Title:
HANDBOOK ON THE PHYSICS AND CHEMISTRY OF RARE EARTHSOriginal File Name Searched:
Chemistry-Rare-Earths-49.pdfDIY PDF Search: Google It | Yahoo | Bing
Sulfur Deposition on Carbon Nanofibers using Supercritical CO2 Sulfur Deposition on Carbon Nanofibers using Supercritical CO2. Gamma sulfur also known as mother of pearl sulfur and nacreous sulfur... More Info
CO2 Organic Rankine Cycle Experimenter Platform The supercritical CO2 phase change system is both a heat pump and organic rankine cycle which can be used for those purposes and as a supercritical extractor for advanced subcritical and supercritical extraction technology. Uses include producing nanoparticles, precious metal CO2 extraction, lithium battery recycling, and other applications... More Info
| CONTACT TEL: 608-238-6001 Email: greg@infinityturbine.com | RSS | AMP |