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Science. 1999 Feb 19;283(5405):1142-5.

Cristobalite in volcanic ash of the soufriere hills volcano, montserrat, british west indies

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Department of Community Medicine, University of Cambridge, Gresham Road, Cambridge, CB12 ES, UK. Department of Earth Sciences, Bristol University, Queens Road, Bristol BS8 1RJ, UK. Department of Physics, University of Warwick, Coventry CV4 7AL, UK. B.


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.

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