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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. Air traffic is grounded within a radius of 200 kilometers. President Barack Obama cut his state visit to Ireland short, 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 examined ash particles from Grimsvötn using an electron microscope made by Carl Zeiss. The particles ranged in size from 2 to 30 thousandths of a millimeter and were scraped off of a car windshield. The ash was found to contain extremely fine particles of volcanic glass. Is this glass comparable to window glass? In principle, yes.

Like most types of stone, volcanic ash and lava are composed of silicates. When the hot, liquid magma cools very fast or is quenched, no crystals can form. 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 usually consists primarily 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 the case for some optical lenses, for example, in order to prevent stress build-up and image distortion. The glass spewed by volcanoes is thus generally unusable.

July 13, 2011