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Cristobalite in Volcanic Ash of the Soufriere Hills Volcano, Montserrat, British West Indies

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Science  19 Feb 1999:
Vol. 283, Issue 5405, pp. 1142-1145
DOI: 10.1126/science.283.5405.1142

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Abstract

Crystalline silica (mostly cristobalite) was produced by vapor-phase crystallization and devitrification in the andesite lava dome of the Soufriere Hills volcano, Montserrat. The sub–10-micrometer fraction of ash generated by pyroclastic flows formed by lava dome collapse contains 10 to 24 weight percent crystalline silica, an enrichment of 2 to 5 relative to the magma caused by selective crushing of the groundmass. The sub–10-micrometer fraction of ash generated by explosive eruptions has much lower contents (3 to 6 percent) of crystalline silica. High levels of cristobalite in respirable ash raise concerns about adverse health effects of long-term human exposure to ash from lava dome eruptions.

  • * To whom correspondence should be addressed. E-mail: steve.sparks{at}bristol.ac.uk

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