Manganite - Black Jack mine, Nevada, USA

Manganite

Help improve this record

No owner is registered for this specimen yet. If it's yours or you know more about it, you can add the owner, provenance, publications and other details.

Lustrous black crystals of manganite covering the top of matrix. In good condition. The Black Jack Mine in Pima County, Arizona, was a small underground manganese operation located within the Papago Indian Reservation. While exact permanent opening and closing dates are not recorded, primary historical production occurred during the mid-1950s (notably active in 1956), followed by additional intermittent development and working phases through 1958 and 1959, after which the property became idle. Geologically, the deposit is classified as a replacement-type ore body characterized by an east-striking bedding-plane fault featuring a quartzite footwall and a limestone hanging wall, with mineralization consisting primarily of psilomelane concentrated along the south wing of an apparent anticline.