Natrocarbonatite

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Sample of natrocarbonatite, 4.1 cm across, from the 1963 pahoehoe lava flow of Ol Doinyo Lengai Natrocarbonatite (1963 pahoehoe lava flow, Old Doinyo Lengai Volcano, East African Rift Valley, northern Tanzania).jpg
Sample of natrocarbonatite, 4.1 cm across, from the 1963 pahoehoe lava flow of Ol Doinyo Lengai
Solidified lava in the crater of Ol Doinyo Lengai Lava lengai.jpg
Solidified lava in the crater of Ol Doinyo Lengai
Crater of Ol Doinyo Lengai with hours-old black natrocarbonatite lava flow and older white natrocarbonatite lava flows, August 2007 Ol Doinyo Lengai Crater.jpg
Crater of Ol Doinyo Lengai with hours-old black natrocarbonatite lava flow and older white natrocarbonatite lava flows, August 2007

Natrocarbonatite is a rare carbonatite lava which erupts from the Ol Doinyo Lengai volcano in Tanzania within the East African Rift of eastern Africa. Natrocarbonatite lavas were first documented in 1962, by J. B. Dawson. [1] [2]

Contents

Composition

Whereas most lavas are rich in silicate minerals, the natrocarbonatite lavas of Ol Doinyo Lengai are rich in two rare sodium and potassium carbonate minerals, nyerereite and gregoryite. [3]

Due to this unusual composition, the lava is erupted at relatively low temperatures (approximately 500–600 °C). [4] This temperature is so low that the molten lava appears black in sunlight, rather than having the red glow common to most lavas. It is also much more fluid than silicate lavas.

Impact

The sodium and potassium carbonate minerals of the lavas erupted at Ol Doinyo Lengai are unstable at the Earth's surface and susceptible to rapid weathering, the minerals are anhydrous and when they come into contact with the moisture of the atmosphere, they begin to react extremely quickly.

The black or dark brown lava and ash erupted begins to turn white within a few hours. The resulting volcanic landscape is different from any other in the world.

Notable appearances

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References

  1. Dawson, J. B. (September 6, 1962). "Sodium Carbonate Lavas from Oldoinyo Lengai, Tanganyika". Nature. 195 (4846): 1075–1076. Bibcode:1962Natur.195.1075D. doi:10.1038/1951075a0. S2CID   4294135 via www.nature.com.
  2. Dawson, J. B. (December 1, 1962). "The geology of Oldoinyo Lengai". Bulletin Volcanologique. 24 (1): 349–387. Bibcode:1962BVol...24..349D. doi:10.1007/BF02599356. S2CID   128470943 via Springer Link.
  3. McKie, Duncan; Frankis, E. J. (January 1, 1977). "Nyerereite: a new volcanic carbonate mineral from Oldoinyo Lengai, Tanzania". Zeitschrift für Kristallographie. 145 (1–2): 73–95. Bibcode:1977ZK....145...73M. doi:10.1524/zkri.1977.145.1-2.73 via www.degruyter.com.
  4. Krafft, Maurice; Keller, Jörg (1989). "Temperature Measurements in Carbonatite Lava Lakes and Flows from Oldoinyo Lengai, Tanzania". Science. 245 (4914): 168–170. Bibcode:1989Sci...245..168K. doi:10.1126/science.245.4914.168. PMID   17787875. S2CID   33271547.