Ilvaite
Obira-Kozan, Ogata, Bungo-Ono city, Oita pref., Japan
Field of view: 40 mm. Ilvaite associated with grunerite. The black prisms with a resinous luster at the center, for example, are ilvaite. The massive pale brown parts in the interstices of ilvaite are aggregate of fine grunerite crystals. The radial groups of platy grayish-brown crystals at the upper right are Stilpnomelane.
Recovered from a pneumatolytic deposit combined with skarn formed by S-type (Ilmenite-series) granite of a caldera complex. Formed in the middle Miocene (14 Ma).
The first ilvaite from Japan was reported from this location in 1893.
Other localities
- Chichibu Mine (Hydrothermal Skarn, Prismatic)
- Horado Mine (Hydrothermal Skarn, Granular)
- Obira Mine (Pneumatolytic Skarn, Prismatic)
- Kamioka Mine (Pneumatolytic Skarn, Granular)