Agates are semi-precious gemstones that are a variegated form of chalcedony (a translucent variety of quartz of various colors and waxy luster). Agates naturally develop when an empty pocket inside a host rock is filled molecule-by-molecule, layer-by-layer as microcrystals form concentric bands or other patterns. The colors and arrangement of the microcrystals are influenced by changes in pressure, temperature, and mineral content that occur during the formation process. Unlike other gemstones, each agate is unique. Even slabs cut from the same specimen will vary in color and design. We are offering a 4.5x6x.75" thick slice of an agate geode, w/an opening measuring 2x2.75" which is coated by a drusy (an aggregate composed of pointed crystals protruding from a cavity or base layer) of microcrystals. At the outer edge of the geode, there is a .5" thick band of dark brown agate banding which gives way to .5" to 1.25" thick band of quartz crystals which in turn gives way to another banding of agate before the geode opened to the microcrystals. The opening goes completely through the slice in three small areas and the bottom has been cut to allow upright display. Both sides have been polished for an Exc. display.