Agate is an aggregate of different forms of silica (SiO2) that have formed concentric bands within a geode.
Silica appears naturally in several crystalline forms, one of the best known is quartz.
Geodes, which derive from the Greek word “Earth-like” are geological secondary formations within sedimentary and volcanic rocks.
Colour variety: Black, Green, Blue, Red, White, Grey, Purple, Yellow, Pink, Orange, Brown
The patterns are formed by mineral impurities.
Where can you find geodes: around the world, but often concentrated in deserts.