Eruption of Eyjafjallajökull in Southern Iceland, Nanoscribe microscope

©C. and W. Schäper

Did You Know…

…that Volcanoes Spew Glass?

Iceland, 21 May 2011, 5:30 p.m.: After seven years of lying dormant, the Grimsvötn volcano erupted again, spewing ash more than 5 kilometers into the sky, and up to 19 kilometers high on the following day, grounding air traffic within a radius of 200 kilometers. President Barack Obama cut short his state visit to Ireland, and the FC Barcelona soccer players flew to the Champions’ League finals in London earlier than planned.

Scotland, 24 May 2011: Scientists at the independent James Hutton Institute in Aberdeen used a ZEISS electron microscope to examine ash particles from Grímsvötn, which had been scraped off of a car windshield and ranged in size from 2 to 30 thousandths of a millimeter. It turned out that the ash contained very fine particles of volcanic glass. Is this glass comparable to manufactured glass? In principle, yes.

Like most types of stone, volcanic ash and lava are composed mainly of silicates. When the hot, liquid magma cools very fast or is quenched with water, crystals are prevented from forming. When Grimsvötn erupted, the glacier on the volcano provided the cooling, during which a large part of the glacial ice evaporated, so that the ash cloud consisted primarily of steam.

Synthetically manufactured glass primarily consists of non-crystalline silicates as well. However, due to the different composition and the manufacturing process, no quenching is necessary. In extreme cases, the cooling process can take up to an entire year. This is done with certain optical lenses for the purpose of preventing stress effects and image distortion. The glass spewed by volcanoes is thus generally unusable.

13 July 2011