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Geosciences LibreTexts

16.50.02: Blue Peruvian Opal

  • Page ID
  • Opal
    Chemical composition SiO2+.H2O
    Crystal system Amorphous
    Hardness 5- 6 1/2
    Refractive index 1.45 (+.020;-0.080)
    Specific gravity 2.15 (+0.07;-0.90)
    Lustre Vitreous
    Phenomenon Play of Color

    The name comes from the source from where it is mined, the Peruvian Andes.
    Other tradenames include Andean opal, Andean blue opal, Andean blue silica, and blue opal.



    Aquamarine to sea-green color due to trace amounts of copper.


    Main source: San Patricio, Peru.


    Opal is relatively soft, Peruvian opal should be treated with care as it can be scratched by any harder material. Wash in warm soapy (non-detergent) water.

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