Bustamite

Field of view: 60 mm. Bustamite replacing tuff. The massive pale brown part at the lower left is bustamite. The bustamite is aggregate of very fine crystals. The dark brown part at the upper right is rich in hematite. The boundary between them is not clear. The black crust on the surface is manganese dioxide formed by weathering.

Recovered from a mudstone-hosted Cu-Mn deposit subjected to Zeolite facies metamorphism.

Bustamite from this location was described in 1982.