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Hydrothermal hexahydrite spherules erupted during the 2008-2010 summit eruption of Kīlauea Volcano, Hawai`i'

January 1, 2011

Small (1-3 mm), hollow spherules of hexahydrite have been collected falling out of the magmatic gas plume downwind of Kīlauea’s summit vent. The spherules were observed on eight separate occasions during 2009-2010 when a lake of actively spattering lava was present ~150-200 m below the rim of the vent. The shells of the spherules have a fine bubbly foam structure less than 0.1 mm thick, composed almost entirely of hexahydrite [MgSO4·6H2O] Small microspherules of lava (<5 μm across) along with mineral and rock fragments from the magmatic plume adhered to the outside of the hexahydrite spherules. Phase relationships and the particulate matter in the magmatic plume indicate that the spherules originated as a bubbly solution injected into and mixed with the magmatic plume. The most likely mechanism for production of hexahydrite spherules is boiling of MgSO4-saturated meteoric water in the walls of the conduit above the surface of the lava lake. Solfataric sulfates may thus be recycled and reinjected into the plume, creating particulates of sulfate minerals that can be distributed far from their original source.

Publication Year 2011
Title Hydrothermal hexahydrite spherules erupted during the 2008-2010 summit eruption of Kīlauea Volcano, Hawai`i'
DOI 10.1007/s00445-011-0484-x
Authors Ken Hon, Tim R. Orr
Publication Type Article
Publication Subtype Journal Article
Series Title Bulletin of Volcanology
Index ID 70032612
Record Source USGS Publications Warehouse
USGS Organization Hawaiian Volcano Observatory