Small opal occurence is located in the serpentinite rocks near the Rožná village, Czech Republic. It yields uncommon opal material with reticulated structures, some of these opals also contain chromite.

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Melanterite is a perishable product of iron ore weathering, forming awesome green stalactites and crusts in the abandoned mines. Its shaky existence is a nice example of natural processes, but admiring melanterite beauty often includes trips to hardly accessible underground places.

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Cinnabar is bright red mercury sulfide, which is a main ore of mercury and used to be a source of red pigments for milleniums. Cinnabar (and mercury) had been a key to mining precious metals until beginning of the 20th century and also saved a millions of teeth.

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Elemental bismuth occurs as a metallic silver mineral often characterized by an oxide tarnish generating a dramatic iridescence of pinks, yellows and greens.

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