all the stamps are silkscreen printed with very fine-grained trachyandesite ash (3 microns (μm) or less) which fell at Eyjafjalla jökull April 17th 2010. The trachyandesite magma has ca. 60% silica content and comes from a depth of 7 km with a temperature of more than 1100°C when it reaches the glacial ice.Trachyandesitic ash is magma with a 60 percent silicon content and was more than 1,100°C (2,012°F) hot when it came in contact with the glacier, the announcement from Iceland Post explained.
The stamps were designed by Borgar Hjörleifur Árnason and Hany Hadaya at H2 design. The photographs are by Óskar Ragnarsson (Fimmvörduháls) and Ragnar Th. Sigurdsson (Eyjafjallajökull, two pictures). The stamps are made with a conventional offset print at the Dutch printery Joh. Enschedé but then later silk-printed with the trachyandesitic ash.
These things will sell like hot cakes! Someone go buy me one!
H/T Erik Klemetti at Scienceblogs.