Bonga

Carbonatite rare-earth element, in Angola country (in Africa)

Deposit type: Carbonatite

REE minerals: parisite, synchysite

Ore minerals: apatite, pyrite, barite, pyrochlore, magnetite, rutile, strontianite, phosphorus

Gangue minerals: garnet, calcite, ankerite-dolomite, biotite

Host rock types: carbonatite, fenite

Average grade:

Status: Occurrence

Company:

Resource estimates:

The Bonga carbonatite complex in Angola belongs to the Paraná-Angola-Etendeka Igneous Province. It crops out as an isolated circular plug in the Precambrian crystalline basement along the intersection of faults. Petrographically, the complex consists of syenite, carbonatite and fenite with some tephritic-phonolitic eruptive breccias. The carbonatite is mainly composed of calcite with minor pyrochlore, apatite, magnetite, fluorite and REE minerals. Enriched in pyrochlore, Bonga is a giant magmatic carbonatite-type niobium deposit. Chemically, the carbonatite belongs to sovite (Ca-carbonatite) and ferrocarbonatite, has high contents of Sr, Ba, Mn, Nb, Th and LREE, and is depleted in K, Ti and U with no Ce and Eu anormalies. These geochemical features indicate that the Bonga intrusion is similar to the other typical igneous Ca- and Fe-carbonatites in the world. Zr/Hf and Y/Ho ratios and normalized Y contents of the rocks suggest that the Bonga carbonatite belongs to a highly evolved magmatic system, transitional between pure melts and hydrothermal fluids. The Bonga niobium deposit formed during magmatic and hydrothermal periods. Reddish brown euhedral pyrochlore (flurocalciopyrochlore and hydroxycalciopyrochlore) crystalized during the early magmatic period, while formation of yellowish green sub-euhedral to anhedral pyrochlore (kenocalciopyrochlore) occurred later during the hydrothermal event.

References

https://en.wikipedia.org
https://nature.desktopnexus.com/wallpaper/1896563/
https://www.researchgate.net/publication/287237909_Geology_geochemistry_and_genesis_of_the_Bonga_carbonatite-type_niobium_deposit_Angola

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