Quartz (Var: Chalcedony)
Cerro del Cinto Mine, Rodalquilar, Níjar, Almería, Andalusia, Spain
High gold grade black chalcedony with pyrite, enargite, naumannite and other sulphides. Gold here was found mainly in a black to dark grey, pyritic, banded chalcedony that filled preexisting open spaces and fractures within rock previously altered to vuggy silicahighest. Gold values in this banded chalcedony reached 0.40 to 380 g/t (median of 8.0 ...
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