These attractive mini agate geodes have been cut and polished to reveal the calming colour and quartz crystals inside. In nature geodes start life as empty cavities such as gas bubbles. As the material around the cavity hardens over time, the flow of ground water or volcanic fluid allows minerals to form inside the empty cavity. Geodes such as these ones which are composed of quartz are highly resistant and they survive while the bedrock around them weathers and erodes thus leaving the geode present at the surface. Naturally the size of these geodes varies but you can expect a specimen of approximately 4 x 2 x 2 cm. Supplied in a tightly sealed blister pack with a detailed information card and a plastic hand lens to enhance the viewing of the sample. An ideal gift for children, beginner geologists and collectors.