Agate - a colorful find from antiquity and modern times
From the outside it looks like an ordinary fieldstone, but inside it hides true works of art. Its beauty has fascinated people since ancient times, which is why the ancient Egyptians were already using it to make rings and vessels around 1000 BC. It owes its name to the rich deposits along the Achates River (now Dirillo) in Sicily: agate, one of the best-known and most popular gemstones in the world.
Agates or banded chalcedony are a variety of quartz - the second most common mineral on earth. They consist of a compound of the two most common elements in the earth's crust, silicon and oxygen (SiO2). In contrast to crystalline quartz varieties such as rock crystal or amethyst, agates are made up of several layers of micro- to cryptocrystalline chalcedony, which are deposited from the outside inwards. The richness of color in agates is due to the smallest admixtures in the solidifying silica (SiO2), which change from layer to layer in the course of precipitation.
The color spectrum of agates ranges from shades of blue - agates from Rio Grande do Sul, Brazil - to red agates, such as those from St. Egidien, Saxony. The sheer abundance of shapes and colors means that agates are named and categorized according to their appearance, such as the apricot agate - an agate with a pink to flesh-coloured hue from Botswana.
The formation process of agates is not yet fully understood. They often occur as cavity fillings in volcanic rocks. The cavities are formed when gases can no longer escape from the molten rock but are trapped in the cooling lava. The silica is deposited afterwards, probably at much lower temperatures. Concentric deposits of gel-like silica are also found as gangue mineralization, in marine sediments, in silicified corals and even in dinosaur bones. They are also not uncommon in fossil wood - the aerial roots of the Psaronius-Tree ferns from the Chemnitz Petrified Forest are largely lined with agates.
Agates were not only popular in ancient Egypt. They were also sought after by the Saxon Elector Augustus the Strong (1670-1733), for example, who promoted the search for "precious stones". They were used in a variety of ways - from mortars to bracelets, tabatiers - boxes for storing snuff - to ornaments and knife handles.
Agates are small cosmopolitans that can be found in many different parts of the world. They can be found in Brazil, Sicily, Brdy - a forest mountain range in central Bohemia - as well as Glashütte, St. Egidien and Chemnitz-Altendorf in Saxony.
Adult groups can cut and polish agates themselves at the Museum für Naturkunde Chemnitz. All visitors can marvel at various agates in the Historical Cabinet. However, if you feel the urge for adventure, you can also search for and dig agates and amethysts yourself on the claim in Schlottwitz.