Jacobsite-Q, "Iwakiite"

Field of view: 30 mm. Jacobsite-Q (Iwakiite) associated with braunite. Iwakiite is corrected to a tetragonal polytype of Jacobsite. The massive black parts are braunite. The coarse greenish-black veins at the top and traversing from the lower left to the center are iwakiite. The left end part mixing with white grains is aggregate of rhodonite and quartz. Maginetic minerals having similar appearance such as iwakiite, jacobsite and magnetite have been reported from this deposit. Iwakiite is distingushed from jacobsite by association with quartz.

Recovered from a bedded manganese deposit subjected to Epidote-Amphibolite facies regional metamorphism and contact metamorphism by granite.

The first iwakiite in the world was described from this location in 1979.