Slice of honeycomb agate, close-up. Agate is an aggregate of different forms of silica within a geode. A geode forms when the silica precipitates from liquid onto the inside surface of an empty pocket in a host rock. This agate gets its name from its honeycomb-like texture, which results from hexagonal crystallisation, and because it is the colour of beeswax. The colours and arrangements of microcrystals are influenced by changes in pressure, temperature, and mineral content that occur during the formation process. Actual width: 13 centimetres.