Dragon Minerals - Update November 1, 2018

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21498: Vivianite
Tomokoni Mine, Machacamarca District, Cornelio Saavedra Province, Potosí Department, Bolivia
Miniature - 4.5 x 1.7 x 1.3 cm (1.8 x 0.7 x 0.5 inches)
Weight - 16 grams (0.04 pounds)
Specimen status: Sold

A deep green (not blue as the photos suggest), opaque to transparent vivianite crystal. The ends appear contacted (not broken) as if the crystal grew across a cavity. Tomokoni Mine vivianites were once rather abundant but are now uncommon. Many have turned black and split apart, as their Fe2+ has air-oxidized to Fe3+ over time. This is probably why this crystal appears dark blue (on the surface) but in fact is a pleasant Coke bottle green under transmitted light. Cleaved along one face.

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