6.3" Polished Mad River (Zyamara) Sagenite Agate - Madagascar

About Agate

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.

Sagenite agate is a formation of agate that contains acicular (needle-like) formations of fanning sagenite crystals encapsulated in a mass of pseudomorphic agate. This occurs when agate fills a cavity within rock that had prior formations of minerals, in this case the golden sagenite crystal clusters.

Sagenite is a name that often refers to acicular rutile crystals, which in this case is accurate. The golden crystals within this specimen are technically rutile (TiO2) crystals.