Agate is a mineralogical formation, a patterned variety of chalcedony. Usually have a striped pattern, usually spherical, but parallel stripes are also found. Agates also include moss and dendroagate, the pattern in which is formed by the inclusion of other minerals or dendrocrystals, respectively.
The formation of agates is of two types: high-temperature (in air bubbles of cooling lava flows) and low-temperature (in karst cavities).
You can see agate stone for sale and buy it in the Minerals of Russia online store.
|SiO2 silicon dioxide|
|Crystal system||Rhombohedral (microcrystalline)|
|Crystal habit||Cryptocrystalline silica|
|Fracture||Conchoidal with very sharp edges|
|Mohs scale hardness||6.5–7|
|Birefringence||up to +0.004 (B-G)|