Chalcedony is a cryptocrystalline variety of quartz. Of volcanic origin, with multiple varieties and colors. In ancient times it represented the elements air and water. In ancient Rome and Greece, it was already used as a material for jewelry. It was a stone considered sacred by the Native American Indians, being used in ceremonies. It is the stone of generosity, harmonizes body and mind. It has deposits all over the world, the most important being in Brazil and India; and in Spain, in Galicia and Aragon.