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Mt Oldoinyo Lengai (Ol Doinyo Lengai), Arusha Region, Tanzania

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Mt Oldoinyo Lengai - view from the Natron lake.

Mt Oldoinyo Lengai, Arusha Region, Tanzania
Strombolian eruption of the new crater of the volcano 08.10.2017

Mt Oldoinyo Lengai, Arusha Region, Tanzania
Mt Oldoinyo Lengai - view from the Natron lake.

Mt Oldoinyo Lengai, Arusha Region, Tanzania
Strombolian eruption of the new crater of the volcano 08.10.2017

Mt Oldoinyo Lengai, Arusha Region, Tanzania
Mt Oldoinyo Lengai - view from the Natron lake.

Mt Oldoinyo Lengai, Arusha Region, Tanzania
Latitude & Longitude (WGS84): 2° 45' 0'' South , 35° 55' 59'' East
Latitude & Longitude (decimal): -2.75000,35.93333
GeoHash:G#: kz983emu5
Locality type:Mountain
Köppen climate type:Aw : Tropical savanna, wet

The world's only active carbonatite volcano, with jacupirangite, nepheline syenite and other rocks. Extremely alkali-rich lava, 30 % Na2O.

Mineral List

61 valid minerals. 4 (TL) - type locality of valid minerals.

Rock Types Recorded

Note: this is a very new system on mindat.org and data is currently VERY limited. Please bear with us while we work towards adding this information!

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Alphabetical List Tree Diagram

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

Holocene - Pleistocene
0 - 2.588 Ma

ID: 2697392
Main-cone volcaniclastic rocks and lava flows

Age: Pleistocene (0 - 2.588 Ma)

Description: Stippled on northwest flank where pyroclastic flow(?) deposits of 2007–08 can be delineated from oblique photography. Less well-defined lava flows are contained within this unit. Lava flows: chiefly nephelinite and phonolite, but includes recent carbonatite on west flank. Subdivided into: Holocene carbonatite lava flows, Pleistocene nephelinite of upper flanks, and Pleistocene phonolite lava flow on lower east-southeast flank. Carbonatite lava flows: Pāhoehoe and ‘a‘ā of 2006 eruption. Nephelinite of upper flanks: remnants of lava flow, highest part of which is sometimes called “Pearly Gates” for the slot traversed through it by westside climbers’ trail

Lithology: Nephelenite and phonolite volcanic rocks

Reference: Sherrod, D.R., Magigita, M.M., and Kwelwa, S. Geologic map of Oldonyo Lengai (Oldoinyo Lengai) and surroundings, Arusha Region, United Republic of Tanzania. doi: 10.3133/ofr20131306. U.S. Geological Survey Open-File Report 2013-1306. [126]

0 - 2.588 Ma

ID: 3306518

Age: Pleistocene (0 - 2.588 Ma)

Lithology: Volcanic

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

2.588 - 23.03 Ma

ID: 3186107
Cenozoic volcanic rocks

Age: Neogene (2.588 - 23.03 Ma)

Lithology: Intermediate volcanic rocks; phonolite

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

This page contains all mineral locality references listed on mindat.org. This does not claim to be a complete list. If you know of more minerals from this site, please register so you can add to our database. This locality information is for reference purposes only. You should never attempt to visit any sites listed in mindat.org without first ensuring that you have the permission of the land and/or mineral rights holders for access and that you are aware of all safety precautions necessary.


Sort by Year (asc) | by Year (desc) | by Author (A-Z) | by Author (Z-A)
Guest, N.J. (1956) The volcanic activity of Oldoinyo L'Engai, 1954. Rec. Geol. Surv. Tanganyika: 4: 56-59
Dawson, J.B. (1962) Sodium carbonatite lavas from Oldoinyo Lengai, Tanganyika. Nature: 195: 1075-1076
Milton, C. (1968) The "natro-carbonatite lava" of Oldoinyo Lengai, Tanzania. Geological Society of America Special Paper 121: 202 (abstract)
Peterson, T.D. (1986) Sodium metasomatism and mineral stabilities in alkaline ultramafic rocks: implications for the origin of the sodic lavas of Oldoinyo Lengai. Eos: 67: 617 (abstract)
Peterson, T.D. (1989) Peralkaline nephelinites II. Low pressure fractionation and the hypersodic lavas of Oldoinyo Lengai. Contributions to Mineralogy and Petrology: 102: 336-346
Peterson, T.D. (1990) Petrology and genesis of natrocarbonatite. Contributions to Mineralogy and Petrology: 105: 143-155
Mitchell, R.H. (1997) Carbonate-carbonate immiscibility, neighborite and potassium iron sulphide in Oldoinyo Lengai natrocarbonatite. Mineralogical Magazine: 61: 779-789
Dawson, J.B. and Hll, P.G. (1998) Mineral chemistry of peralkaline combeite-lamprophyllite nephelinite from Oldoinyo Lengai, Tanzania. Mineralogical Magazine: 62: 179-196
Pettibon, C.M., Kjarsgaard, B.A., Jenner, G.A., and Jackson, S.E. (1998) Phase relationships of a silicate-bearing natrocarbonatite from Oldoinyo Lengai at 20 and 1000 MPa. Journal of Petrology: 39: 2137-2151
Jago, B. C., & Gittins, J. (1999). Mn-and F-bearing rasvumite in natrocarbonatite at Oldoinyo Lengai volcano, Tanzania. Mineralogical Magazine, 63(1), 53-55.
Genge MJ, Balme B, Jones AP (2001): Salt-bearing fumarole deposits in the summit crater of Oldoinyo Lengai, Northern Tanzania: Interactions between natrocarbonate lava and meteoric water. J. Volcanology 106, 111-122.
Mitchell, R.H. and Belton, F. (2004) Niocalite-cuspidine solid solution and manganoan monticellite from natrocarbonatite, Oldoinyo Lengai, Tanzania. Mineralogical Magazine: 68: 787-799
Mitchell, R.H. (2006) Mineralogy of stalactites formed by subaerial weathering of natrocarbonatite hornitos at Oldoinyo Lengai, Tanzania. Mineralogical Magazine: 70: 437-444
Keller, J., & Zaitsev, A. N. (2006). Calciocarbonatite dykes at Oldoinyo Lengai, Tanzania: the fate of natrocarbonatite. The Canadian Mineralogist, 44(4), 857-876.
Zaitsev, A. N., & Keller, J. (2006). Mineralogical and chemical transformation of Oldoinyo Lengai natrocarbonatites, Tanzania. Lithos, 91(1), 191-207.
Dawson, B. (2008): A volcanic voyage of discovery. Elements, 4, 138-139
Anatoly N. Zaitsev, A.N., Zaitseva, O.A., Buyko, A.K., Keller, J., Klaudius, J. and Zolotarev. (2009). Gem-quality yellow-green hauyne from Oldoinyo Lengai volcano, Nothern Tanzania. Gems & Gemology, 45(3), 200-203.
Mattsson, H. B., & Reusser, E. (2010). Mineralogical and geochemical characterization of ashes from an early phase of the explosive September 2007 eruption of Oldoinyo Lengai (Tanzania). Journal of African Earth Sciences, 58(5), 752-763.
Bosshard-Stadlin, S. A., Mattsson, H. B., & Keller, J. (2014). Magma mixing and forced exsolution of CO 2 during the explosive 2007–2008 eruption of Oldoinyo Lengai (Tanzania). Journal of Volcanology and Geothermal Research, 285, 229-246.
Zaitsev, A.N., Britvin, S.N., Kearsley, A., Wenzel, T., Kirk, C. (2017): Jörgkellerite, Na3Mn3+3(PO4)2(CO3)O2·5H2O, a new layered phosphate-carbonate mineral from the Oldoinyo Lengai volcano, Gregory rift, northern Tanzania. Mineralogy and Petrology 111, 373–381.

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