Natrocarbonatite

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]

Solidified lava in the crater of Ol Doinyo Lengai.
Crater of Ol Doinyo Lengai with recent (hours-old at time of photograph) lava flow.

Composition

Whereas most lavas are rich in silicate minerals, the natrocarbonatite lavas of Ol Doinyo Lengai are rich in the 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

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.


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