Large Agate Slices Agate & Quartz Geodes/Slices items can be found here. We sell these wholesale and retail and have done for years, they are very popular at shows and festivals. As they are natural products, there is always minor defects and imperfections in the pieces and that's to be expected in something so old. The pieces have been cut, polished, cut base for ease of display, and dyed their colours where they are found in Brazil. Agate is a microcrystalline Quartz and when these pieces are lit with a light behind, they come alive!