Siegenite

specimen number:
2262076

location:
Mine La Motte, Madison Co., Missouri, USA

description:
An outstanding old time specimen for this rare mineral from Missouri. The top of this matrix is richly scattered with bright lustrous octahedral crystals of siegenite measuring to 0.4 cm in size. This is in great condition. Specimen such as this from this old locality are hardly ever seen available on the market today.

Mine La Motte, located in Madison County, Missouri, is one of the oldest lead mines in the United States and serves as a key component of the Fredericktown sub-district of the Southeast Missouri Lead District. Geologically, the mineralization is hosted within the Cambrian-aged Lamotte Sandstone and Bonneterre Formation, where Mississippi Valley-type (MVT) fluids deposited lead, copper, nickel, and cobalt sulfides along the Precambrian basement unconformity. The locality is renowned for producing siegenite, a cobalt-nickel sulfide that occurs as metallic, steel-gray octahedral crystals or granular masses, often found in association with chalcopyrite and galena. Historically, mining and quarrying at the site began as early as 1723 under French explorers, with intermittent production spanning over two centuries. Industrial activity peaked during the late 19th and early 20th centuries as various companies, including the Mine La Motte Corporation, expanded underground workings to extract both lead and cobalt-nickel ores. While large-scale operations eventually concluded by the late 1950s, the site remains a premier mineralogical locality for the study of transition metal sulfides and the early industrial history of the American Midwest through 2026.

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