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Sapphire alluvials, Andamby, Djangoa Commune, Ambanja District, Diana Region (Northern Region), Antsiranana Province, Madagascar

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Latitude & Longitude (WGS84): 13° 46' 32'' South , 48° 21' 2'' East
Latitude & Longitude (decimal): -13.77583,48.35083
GeoHash:G#: mjd3sk0jb
Locality type:Alluvials
Köppen climate type:Am : Tropical monsoon climate
Name(s) in local language(s):Andamby, Kaominin'i Djangoa, Distrikan' Ambanja, Faritr'i Diana, Faritanin' Antsiranana, Madagasikara


A new site with alluvial sapphires discovered in May or June 2011 by local rice farmers. Presently (August 2011) worked by some 1,000 to 2,000 diggers. To date, sapphires have been found over an NW-SE trending area measuring approximately 500 x 100 m. The diggers follow a thin, 3 to 5 cm thick layer of sapphire bearing gravel at a depth of 3 to 6 m. The host rock of the primary mineralization is not known but presumably it is an alkaline basalt.

The site is situated right on the National Highway RN6 linking Antananarivo with Diego-Suarez, just some 14 km before you reach Ambanja.

Update June 2012: After not even a year of extensive digging all artisanal mining has ceased. After the rainy season which stopped in April, all pits are flooded. It remains doubtful if the local sapphire diggers will resume mining during the dry season (site visit by Wolfgang Hampel, 27 May 2012).


Commodity List

This is a list of exploitable or exploited mineral commodities recorded at this locality.


Mineral List


2 valid minerals.

Regional Geology

This geological map and associated information on rock units at or nearby to the coordinates given for this locality is based on relatively small scale geological maps provided by various national Geological Surveys. This does not necessarily represent the complete geology at this locality but it gives a background for the region in which it is found.

Click on geological units on the map for more information. Click here to view full-screen map on Macrostrat.org

Quaternary
0 - 2.588 Ma



ID: 3311701

Age: Pleistocene (0 - 2.588 Ma)

Lithology: Sedimentary

Reference: Thiéblemont, D. (ed.). New edition of the 1:10,000,000 geological map of Africa. CGMW-BRGM. [190]

Jurassic
145 - 201.3 Ma



ID: 3189234
Mesozoic sedimentary rocks

Age: Jurassic (145 - 201.3 Ma)

Lithology: Sedimentary rocks

Reference: Chorlton, L.B. Generalized geology of the world: bedrock domains and major faults in GIS format: a small-scale world geology map with an extended geological attribute database. doi: 10.4095/223767. Geological Survey of Canada, Open File 5529. [154]

Data and map coding provided by Macrostrat.org, used under Creative Commons Attribution 4.0 License



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