Siderite

Field of view: 30 mm. Siderite associated with kaolinite. The rhombohedral dark brown grains are siderite. The translucent white basement is gangue quartz. The earthy opaque white parts on quartz and siderite at the lower right are kaolinite.

Recovered from a quartz vein of a moderate-temperature hydrothermal deposit probably associated with welded tuff. Formed in the early Paleocene (65 Ma).

Siderite from this location was described in 1972.