1.7" Chatoyant Binghamite Agate Cabochon - Minnesota
This is a beautiful binghamite cabochon that was collected from the Cuyuna Iron Range in Crow Wing County, Minnesota. It is shaped and polished to a mirror-finish and features vibrant and chatoyant red and yellow coloration. There are also sections of iron and/or iron oxide that exhibit beautiful metallic luster. Pictures truly don't do this specimen justice.
Binghamite, also known as "silkstone" or "cuyunite", is a highly sought after variety of agate that is only known to come from one location in Minnesota. This agate formation is found near the Cuyuna iron range in Crow Wing County, Minnesota. It often displays vibrant red, orange and yellow colors and in some cases contains small veins of iron running throughout the agate. Many specimens have chatoyant properties that are similar to tiger's eye. The chatoyance can be attributed to the fibrous hematite and goethite parallel crystal formations that the agate deposits around.
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.