Reticulite

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Reticulite from the volcano Kīlauea ( Hawaii )

The reticulite , also known as "glass foam", is one of the representatives of the pyroclastic rocks . They are characterized as exceptionally gas-rich pumice stones with an extremely low rock content of 0.5–1.5%. This very rare rock , mainly observed on the Kīlauea volcano on Hawaii and the Piton de la Fournaise on Réunion , has a density of 0.02–0.03 g / cm 3 and is therefore the lightest rock in the world. The rock was originally called thread-lace scoria by the American mineralogist James Dana . Despite the low density of the rock, the reticulite does not swim in water like most pumice stones because the air-filled cavities of the reticulite are connected to one another and fill with water. Due to the rare occurrence of the rock and the irregular composition, reticulite has no technical use.

genesis

Peles hair from the Piton de la Fournaise (Réunion)
Reticulite blown into a tree during an eruption of Kīlauea in 1969 (diameter: 15 cm)

Hot, thin, basaltic lava can carry large amounts of gas with it during a volcanic eruption. The gas expands as a result of the sudden drop in pressure during the fountain-like eruption , so that the small gas bubbles burst and combine to form larger cavities. The pumice-like scraps of lava are pulled out into a filigree network of volcanic glass threads in the air. Depending on the degree of deformation during the cooling of the filaments in the air results in a net-like structure, the Reticulit, thin glass strands and teardrop-shaped structures that after the Hawaiian volcano goddess Pele as Pele's hair or Peles Tears are called.

See also

literature

  • Margaret T. Mangan, Katharine V. Cashmana: The structure of basaltic scoria and reticulite and inferences for vesiculation, foam formation, and fragmentation in lava fountain. In: Journal of Volcanology and Geothermal Research. Vol. 73, No. 1/2, September 1996, ISSN  0022-5398 , pp. 1-18, doi : 10.1016 / 0377-0273 (96) 00018-2 .

Web links

Individual evidence

  1. ^ Lutz Nasdala: Reticulit. In: Mineral World. Vol. 8, Issue 1, 1997, ISSN  0939-6640 , p. 53 f.
  2. ↑ USGS: Volcano Hazard Program: Reticulite , accessed June 3, 2013.
  3. ↑ Martin Okrusch , Siegfried Matthes: Mineralogie. An introduction to special mineralogy, petrology and geology. 7th, completely revised and updated edition. Springer, Berlin et al. 2005, ISBN 3-540-23812-3 , p. 225.