By an official decision by the UN, the year 2014 was declared the International Year of Crystallography. This ephemerid is organized by the International Union of Crystallography (IUCr) and UNESCO. [...] Although today the Crystallography is basilar to all Fundamental Sciences (Chemistry, Physics, Mathematics, Biology and Geology), still remains relatively unknown to the general public. One of the goals of this anniversary is to promote education and awareness. [...] It is intended that each stamp demonstrate the application of crystallography in basic science studies like the Patterson function. Translated by SFAAC. Original text by Elizabeth Silva (in charge for the Sciences group of the National Commission of UNESCO) The € 0.72 stamp is dedicated to Mathematics and pyrite crystals, with the Patterson function.