PDF Publication Title:
Text from PDF Page: 291
REE Mineralogy and Resources Chapter 279 255 Drilling project revealed that there are fresh (deep zone) (Fig. 54C) and hydrothermal altered HREE-rich ferro-actinolite rocks (shallow zone) (Fig. 54B). The former are blackish rocks, the latter are greenish–yellowish rocks, and both of them contain reddish apatite (Fig. 54). Modal abundance of the HREE-rich ferro-actinolite rocks is 80% ferro-actinolite, 12% Fe-oxide, 5% apatite, 0.4% monazite, 0.2% xenotime, 0.3% plagioclase, and 0.3% fluorite. As mentioned earlier, the hydrothermally altered ferro-actinolite rocks from the shallow zone contain REE-poor apatite grains replaced by REE-phosphates such as xenotime-(Y) and monazite-(Nd) (Fig. 53). On the other hand, apatite grains in the fresh ferro-edenite rocks from the deeper zone consist of REE-rich cores (with up to 20.3 wt.% REE2O3) and REE-poor rims including REE phosphate inclusions (Table 16 and Fig. 56B). Generally, apa- tite grains contain 0.5–1 wt.% REE2O3 (Preston et al., 1996). Previous studies suggest that some of IOA deposits and prospects such as Kiirunavaara are associated with REE enrichment, but REE content in apatite grains from these deposits is about 9500 ppm (Table 16). Thus REE-rich apatite in ferro-edenite from the Blockspruit prospect probably has the highest REE contents among REE-bearing apatite reported so far (Table 16). The REE-poor rim of apatite from fresh ferro-edenite in deep zone contains small monazite-(Nd) and xenotime-(Y) inclusions (Fig. 56B). This texture is similar to apatite in hydro- thermal altered ferro-actinolite rocks (Fig. 56A). These textual observations allow one to distinguish the REE mineralization in the Blockspruit fluorite prospect into the following two stages: (1) the first is related to magmatic ferro-edenite intrusive rocks accompanying REE-rich apatite and (2) the sec- ond is related to the decomposition of REE-rich apatite and reprecipitation of monazite-(Nd) and xenotime by hydrothermal alteration. Magmatic ferro- edenite rocks containing HREE-rich apatite intrude into granite. After that, REEs in the magmatic HREE-rich apatite are leached by hydrothermal fluid accompanied by fluorite mineralization and newly precipitate as monazite- (Nd) and xenotime-(Y). Ferro-edenite was also altered to ferro-actinolite dur- ing hydrothermal alteration. Monazite and xenotime, generally being heavy minerals resistant to chemical decomposition and erosion, are concentrated with other heavy resistant minerals in placer deposits, principally in river and beach sands (Sengupta and Van Gosen, 2016). On surface, weathering of ferro-actinolite rocks including apatite-bearing monazite and xenotime inclusions progresses, which results in the decomposition of apatite and resi- dues of monazite and xenotime in the weathered soil. It is easy to collect the thick weathered crust near the surface (30–50 m) which does not need to be crushed, and this will be an advantage for the development of the Blockspruit. It is an important key for the development of this prospect whether monazite and xenotime concentrates can be produced or not by mineral processing. The Na content in HREE-rich apatite from the Blockspruit prospect is below detection limit by EMPA as well as those from Benjamin River prospect, which suggests that REE incorporation into the Blockspruit apatite is achievedPDF 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 (Standard Web Page)