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Lake Magadi, Kajiado County, Kenya

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Latitude & Longitude (WGS84): 1° 52' 59'' South , 36° 16' 0'' East
Latitude & Longitude (decimal): -1.88333,36.26667
GeoHash:G#: kz9v330sf
Locality type:Lake
Köppen climate type:Aw : Tropical savanna, wet


Soda lake.
Also extensive deposits of chert.
In June 1959, E.P. Saggerson and B.H. Baker of the Geological Survey of Kenya discovered a number of small alkaline intrusions in upper Tertiary lavas on the Nguruman Escarpment, which forms the western wall of the Rift Valley about seventy miles south west of Nairobi. During a detailed examination of these intrusions in 1960, they found the alkaline rocks to be emplaced in a flow of ankaratrite (biotite-olivine melanephelinite), that is evidently intercalated in more common olivine basalts. The intrusions, which are probably of upper Tertiary age, are closely controlled by two north-south vertical fault zones in the ankaratrite. Narrow dykes feed sills about 2 ft. thick and these thin rapidly into an intricate network of veins.

Regions containing this locality

Rift Valley Province, Kenya

Province - 135 mineral species & varietal names listed

Select Mineral List Type

Standard Detailed Strunz Dana Chemical Elements

Mineral List


7 valid minerals. 3 (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!

Select Rock List Type

Alphabetical List Tree Diagram

Detailed Mineral List:

'Ankaratrite'
Reference: Saggerson, E.P., Williams, L.A.J. (1964) Ngurumanite from Southern Kenya and its Bearing on the Origin of Rocks in the Northern Tanganyika Alkaline District. Journal of Petrology, Volume 5:1, 1 January 1964, Pages 40–81. https://doi.org/10.1093/petrology/5.1.40
'Chabazite'
Reference: Hay, R.L. (1964) Phillipsite of Saline Lakes and Soils. The American Mineralogist, 49, 1366-1387.
'Chert'
Reference: Hay, R.L. (1968) Chert and its sodium silicate precursors in sodium carbonate lakes of East Africa. Contributions to Mineralogy and Petrology 17, 255-274. Eugster, H.P. (1969) Inorganic bedded cherts from the Magadi area, Kenya. Contributions to Mineralogy & Petrology: 22: 1-31.
'Clinoptilolite'
Reference: Hay, R.L. (1964) Phillipsite of Saline Lakes and Soils. The American Mineralogist, 49, 1366-1387.
'Erionite'
Reference: Hay, R.L. (1964) Phillipsite of Saline Lakes and Soils. The American Mineralogist, 49, 1366-1387.
Halite
Formula: NaCl
Reference: Nielsen, J.M. (1999) East African magadi (trona): fluoride concentration and mineralogical composition. Journal of African Earth Sciences: 29: 423-428.
'Ijolite'
Reference: Saggerson, E.P., Williams, L.A.J. (1964) Ngurumanite from Southern Kenya and its Bearing on the Origin of Rocks in the Northern Tanganyika Alkaline District. Journal of Petrology, Volume 5:1, 1 January 1964, Pages 40–81. https://doi.org/10.1093/petrology/5.1.40
Kenyaite (TL)
Formula: Na2Si22O41(OH)8 · 6H2O
Reference: McAtee, J.L., House, R., Eugster, H.P. (1968) Magadiite from Trinity County, California. The American Mineralogist, 53, 2061-2069. HB2/1 (1995).
Magadiite (TL)
Formula: Na2Si14O29 · 11H2O
Reference: McAtee, J.L., House, R., Eugster, H.P. (1968) Magadiite from Trinity County, California. The American Mineralogist, 53, 2061-2069. HB2/2 (1995). New data on minerals. M.: 2003. Volume 38 pp113.
Makatite (TL)
Formula: Na2Si4O8(OH)2 · 4H2O
Reference: Sheppard, R.A., Gude, A.J. (1970) Makatite, A new hydrous sodium silicate mineral from Lake Magadi, Kenya. The American Mineralogist, 55, 358-366. HB2/2 (1995).
Nahcolite
Formula: NaHCO3
Reference: Geological Society of America Abstracts with Programs, Vol. 42, No. 5, p. 404
'Olivine basalt'
Reference: Saggerson, E.P., Williams, L.A.J. (1964) Ngurumanite from Southern Kenya and its Bearing on the Origin of Rocks in the Northern Tanganyika Alkaline District. Journal of Petrology, Volume 5:1, 1 January 1964, Pages 40–81. https://doi.org/10.1093/petrology/5.1.40
'Phillipsite'
Reference: Hay, R.L. (1964) Phillipsite of Saline Lakes and Soils. The American Mineralogist, 49, 1366-1387.
Trona
Formula: Na3H(CO3)2 · 2H2O
Reference: Nielsen, J.M. (1999) East African magadi (trona): fluoride concentration and mineralogical composition. Journal of African Earth Sciences: 29: 423-428.
'Uhligite'
Formula: Ca3(Ti,Al,Zr)9O20 ?
Description: Discredited by IMA in 2006 (IMA 06–C), possible perovskite or zirkelite(?).cf. Burke 2006.
Reference: New data on minerals. M.: 2003. Volume 38 pp113.
'Uvite Series'
Formula: Ca(Mg3)MgAl5(Si6O18)(BO3)3(OH)3(F/OH)
Villiaumite
Formula: NaF
Reference: Nielsen, J.M. (1999) East African magadi (trona): fluoride concentration and mineralogical composition. Journal of African Earth Sciences: 29: 423-428.

List of minerals arranged by Strunz 10th Edition classification

Group 3 - Halides
'Halite'3.AA.20NaCl
'Villiaumite'3.AA.20NaF
Group 5 - Nitrates and Carbonates
'Nahcolite'5.AA.15NaHCO3
'Trona'5.CB.15Na3H(CO3)2 · 2H2O
Group 9 - Silicates
'Kenyaite' (TL)9.HA.10Na2Si22O41(OH)8 · 6H2O
'Magadiite' (TL)9.EA.20Na2Si14O29 · 11H2O
'Makatite' (TL)9.EE.45Na2Si4O8(OH)2 · 4H2O
'Uvite Series'9..Ca(Mg3)MgAl5(Si6O18)(BO3)3(OH)3(F/OH)
Unclassified Minerals, Rocks, etc.
'Ankaratrite'-
'Chabazite'-
'Chert'-
'Clinoptilolite'-
'Erionite'-
'Ijolite'-
'Olivine basalt'-
'Phillipsite'-
'Uhligite'-Ca3(Ti,Al,Zr)9O20 ?

List of minerals arranged by Dana 8th Edition classification

Group 8 - MULTIPLE OXIDES CONTAINING NIOBIUM,TANTALUM OR TITANIUM
Miscellaneous
'Uhligite'8.7.2.1Ca3(Ti,Al,Zr)9O20 ?
Group 9 - NORMAL HALIDES
AX
Halite9.1.1.1NaCl
Villiaumite9.1.1.3NaF
Group 13 - ACID CARBONATES
Miscellaneous
Nahcolite13.1.1.1NaHCO3
Trona13.1.4.1Na3H(CO3)2 · 2H2O
Group 61 - CYCLOSILICATES Six-Membered Rings
Six-Membered Rings with borate groups
'Uvite Series'61.3.1.3Ca(Mg3)MgAl5(Si6O18)(BO3)3(OH)3(F/OH)
Group 74 - PHYLLOSILICATES Modulated Layers
Modulated Layers with joined strips
Makatite (TL)74.3.5.2Na2Si4O8(OH)2 · 4H2O
Group 78 - Unclassified Silicates
Kenyaite (TL)78.7.7.1Na2Si22O41(OH)8 · 6H2O
Magadiite (TL)78.7.12.1Na2Si14O29 · 11H2O
Unclassified Minerals, Rocks, etc.
'Ankaratrite'-
'Chabazite'-
'Chert'-
'Clinoptilolite'-
'Erionite'-
'Ijolite'-
'Olivine basalt'-
'Phillipsite'-

List of minerals for each chemical element

HHydrogen
H KenyaiteNa2Si22O41(OH)8 · 6H2O
H MagadiiteNa2Si14O29 · 11H2O
H MakatiteNa2Si4O8(OH)2 · 4H2O
H NahcoliteNaHCO3
H TronaNa3H(CO3)2 · 2H2O
CCarbon
C NahcoliteNaHCO3
C TronaNa3H(CO3)2 · 2H2O
OOxygen
O KenyaiteNa2Si22O41(OH)8 · 6H2O
O MagadiiteNa2Si14O29 · 11H2O
O MakatiteNa2Si4O8(OH)2 · 4H2O
O NahcoliteNaHCO3
O TronaNa3H(CO3)2 · 2H2O
O UhligiteCa3(Ti,Al,Zr)9O20 ?
FFluorine
F VilliaumiteNaF
NaSodium
Na HaliteNaCl
Na KenyaiteNa2Si22O41(OH)8 · 6H2O
Na MagadiiteNa2Si14O29 · 11H2O
Na MakatiteNa2Si4O8(OH)2 · 4H2O
Na NahcoliteNaHCO3
Na TronaNa3H(CO3)2 · 2H2O
Na VilliaumiteNaF
AlAluminium
Al UhligiteCa3(Ti,Al,Zr)9O20 ?
SiSilicon
Si KenyaiteNa2Si22O41(OH)8 · 6H2O
Si MagadiiteNa2Si14O29 · 11H2O
Si MakatiteNa2Si4O8(OH)2 · 4H2O
ClChlorine
Cl HaliteNaCl
CaCalcium
Ca UhligiteCa3(Ti,Al,Zr)9O20 ?
TiTitanium
Ti UhligiteCa3(Ti,Al,Zr)9O20 ?
ZrZirconium
Zr UhligiteCa3(Ti,Al,Zr)9O20 ?

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: 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]

Neogene
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

References

Sort by

Year (asc) Year (desc) Author (A-Z) Author (Z-A)
Baker, B.H. (1958) Geology of the Magadi area. Geological Survey of Kenya report No. 42.
Hay, R.L. (1964) Phillipsite of Saline Lakes and Soils. The American Mineralogist, 49, 1366-1387.
Saggerson, E.P. and Williams, L.A.J. (1964) Ngurumanite from Southern Kenya and its Bearing on the Origin of Rocks in the Northern Tanganyika Alkaline District. Journal of Petrology, Volume 5:1, 1 January 1964, Pages 40–81.
Eugster, H.P. (1967) Hydrous sodium silicates from Lake Magadi, Kenya; precursors of bedded chert. Science: 157: 1177-1180.
Eugster, H.P. and Jones, B.F. (1968) Gels composed of sodium aluminum silicate, Lake Magadi, Kenya. Science: 161: 160-164.
Eugster, H.P. (1969) Inorganic bedded cherts from the Magadi area, Kenya. Contributions to Mineralogy & Petrology: 22: 1-31.
Nielsen, J.M. (1999) East African magadi (trona): fluoride concentration and mineralogical composition. Journal of African Earth Sciences: 29: 423-428.

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