Mineral: Bournonite
Locality: Víboras Mine, Machacamarca, Machacamarca District, Cornelio Saavedra Province, Potosí Department, Bolivia
Dimensions: 2.5 cm x 3.8 cm

Description: Intergrown group of lustrous metallic silvery-gray bournonite crystals to 2.4 cm. that exhibit classic “cogwheel” twinning.

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