5.4" Polished Patagonia Crater Agate - Highly Fluorescent!

Crater agate, known by the locals as Orellanita, is categorized by its stunning red color which contrasts nicely against the hazy black chalcedony. They come from the Crater agate beds about 6 miles northwest of Las Plumas in the Chubut Province of Argentina. Crater agate forms as nodules that are found buried within the decomposed basaltic host rock. In rare cases, the botryoidal agate lined pockets can contain quartz and even amethyst. Often the agate exhibits a vivid green fluorescence that in some specimens is second to none.

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 rocks and/or fossils, depositing the silica along the walls of the rock. This process can result in banding patterns, as the compositions and impurities of these depositing fluids change over time. These banding patterns can either form as flat layers, creating linear patterns known as waterline agate, or as rounded layers, forming more common ring-like patterns. These patterns depend on the surfaces available for deposition.