Saima U-REE deposit, Saima complex, Fengcheng Co., Dandong Prefecture, Liaoning Province (Manchuria; Dongbei Region), China

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Uranium deposit with significant REE, thorium and niobium contents, hosted in sodium-rich aegirine-nepheline syenites in the northwestern part of the Saima complex. Depending on the colour of the aegirine, several petrographic varieties of the host rock are distinguished: grass green aegirine syenite and green aegirine-nepheline syenite, which both grade into grass green aegirine-eudialyte-nepheline syenite at depth. These rocks are cut by veins of dark green aegirine-nepheline syenite and by pegmatite, aplite and lamprophyre dykes and pockets, and also contain abundant xenoliths of earlier intrusive rocks. In the western part of the deposit, where the intrusive rocks contact dolomitic marble, steeply dipping skarn zones are developed. Earlier skarns are magnesian or calcic-magnesian in composition (humite-spinel-forsterite skarns, phlogopite-tremolite skarns, etc.) while later skarns (termed "alkaline skarns") are composed of arfvedsonite, magnesian arfvedsonite, microcline and nepheline. In the upper part of the deposit, primary nepheline syenites were transformed by meso-epithermal alteration into rocks resembling alkali syenites in colour and composition (termed "episyenites"). Much of the deposit has also been affected by late hydrothermal alteration.

The main ore-bearing rock is grass green aegirine syenite which contains uraniferous rinkite as the main ore mineral. This type of ore accounts for more than 90% of the uranium reserves. Rinkite and its hydrothermal alteration products (REE carbonates, vudyavrite, fluorite and various U-Th minerals) are also the main carriers of REE and Nb in the deposit. Another 5% of the uranium reserves is contained in pyrochlore group minerals, which occur as disseminations or veinlets in alkaline skarns, and subordinately in episyenites and tremolite skarns. Episyenites in the upper part of the deposit also contain scarce veinlets of pitchblende associated with base metal sulfides.

References

- Saima Deposit Research Group, Beijing Institute of Uranium Geology (1978): Uranium Deposit in the Saima Alkaline Massif, Northeast China. Scientia Sinica 11(3), 365-389.
- Wu, C., Yuan, Z., and Bai, G. (1996): Rare earth deposits in China. In: Jones, A.P., Wall, F., and Williams, C.T. (Eds.): Rare Earth Minerals: Chemistry, origin and ore deposits. The Mineralogical Society Series, Vol. 7. Chapman & Hall (London), pp. 281-310.
- Orris, G.J., and Grauch, R.I. (2002): Rare Earth Element Mines, Deposits and Occurrences. USGS Open-File Report 02-189, 174 pp.
- Dahlkamp, F.J. (2009): Uranium Deposits of the World. Springer (Berlin, Heidelberg), pp. 31-156.

External Links

http://math.scichina.com:8081/sciAe/fileup/PDF/78ya0365.pdf

Mineral List

Aegirine Aegirine-augite Albite Analcime Anatase Andradite var: Melanite 'Apatite' Arfvedsonite Biotite Brookite Calcite Cancrinite Catapleiite

Chalcopyrite 'Chlorite Group' Diopside Eudialyte Fluorite Forsterite Galena Humite Illite Ilmenite Lamprophyllite Limonite Loparite-(Ce)

Microcline Mosandrite Natrolite Nenadkevichite Nepheline Orthoclase Pectolite Phlogopite Pyrite 'Pyrochlore' Pyrochlore Supergroup var: Betafite (of Hogarth 1977) Quartz var: Chalcedony

Rinkite Sphalerite Spinel Strontianite Thorianite var: Aldanite var: Uranothorianite Thorite var: Uranothorite Titanite Tremolite Uraninite var: Pitchblende Uranpyrochlore 'Vudyavrite' Zircon

52 entries listed. 39 valid minerals.