This Specimen has been sold.
5" Polished Thunderegg Slice (Moss Agate) - Richardson Ranch, Oregon
This is a "thunderegg" geode slice, collected from Richardson's Rock Ranch just northeast of Madras, Oregon. It's filled with yellow-orange mossy formations and agate, and comes with an acrylic display stand.
Agate is a variety of microcrystalline quartz (chalcedony) that displays translucence and in some cases banding. Agate primarily forms when silica-rich fluids fill pockets within rock and/or fossils, resulting in deposition of the silica along the walls of the rock. This process can result in banding patterns as the composition and impurities of the fluids change over time. These banding patterns can either form as flat layers or rounded layers, depending on the surfaces available for deposition.