Berthierite

Field of view: 10 mm. Berthierite in sericite. The dark gray prisms are berthierite. The surrounding opaque white parts are massive aggregate of sericite, and the translucent white parts are gangue quartz. Pyrite crystals were found in the same occurrence but pyrite is not associated with berthierite.

Recovered from a sericitization alteration zone associated with a hydrothermal deposit along a fracture zone near the Median Tectonic Line. Formed in the middle Miocene (15 Ma),

Berthierite from this location was described in 1912 as stibnite.