ETYMOLOGY: From the sanskrit "upala" = stone changes the color.
CRYSTAL SYSTEM: Amorphous.
PRINCIPLE OF FORMATION: Secondary.
CLASS MINERAL: Silicates.
CHEMICAL FORMULA, MINERAL ELEMENTS: SiO2 ·nH2O + Cu.
HARDNESS: 5.5 - 6.5 on the Mohs scale.
FIELDS: Peru, Brazil.
MINERALOGY: The group Opal distinguish between nobles opalescent opals, opals red yellow fire and common opals. The properties vary considerably. The opal is secondarily formed as a result of solidification of silicic acid gel by dehydration. Since silicic acid gel forms droplets silicon dioxides microspheres are formed. (20% water and gas). The opal color play is due to the phenomenon of light refraction in the microspheres of cristobalite.
MYTHOLOGY: The common opal, also called potch, in Greek mythology was said to come from the tears of the fate of Zeus after the victory over the Titans. India is the goddess of the rainbow solidified in stone when he fled from the gods angry. Opal cristobalite has small areas included in a mass of hydrated silica gel, when these small areas are of equal size and an ordered three-dimensional distribution of the optical effect opalescence occurs, however when the small spheres are of different sizes and they are arranged irregularly opalescent effects not present.
PROPERTIES: It is said that the blue opal favors empathy, improves communication, helps to understand others and to express themselves clearly indicates solutions to the difficulties, stimulates creativity and encourages communication, comforting emotions, blue mineral has a cooling effect and soothing, promotes relaxation, sincerity and openness.
ZODIAC SIGN: Aquarius.
USES: Jewellery, meditation, collection.