7.1" Nipomo Sagenite Agate Slab - Freddie Quarry, California

This is a gorgeous slab of Nipomo Sagenite Agate that was collected from Freddie Quarry in San Luis Obisbo County, California. It is polished to a mirror-finish on one side and features beautiful fanning sagenite crystal formations that formed in association with marcasite. The marcasite can be noted by its metallic luster and is found along the edges of the rock at the edges of the slab.

There is a natural fracture that runs through the specimen.

An acrylic display stand will accompany your purchase.

Sagenite agate is a formation of agate that contains acicular (needle-like) formations of fanning sagenite crystals that have been 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 being the golden sagenite crystal clusters. Specimens that come from Freddie Quarry in San Luis Obispo County, California can contain both formations of sagenite and metallic marcasite that formed in association, prior to being surrounded in agate.

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.

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.

Quartz var. Agate, Sagenite & Marcasite
Freddie Quarry, San Luis Obispo County, California
7.1 x 6.8", .18" thick