A Shimmering layer of precious opal on dark parent rock with a lively play of colors, named after the area of Australia where it originated. Especially valuable specimens also feature the color red.
Formula: SiO2 + H2O
Hardness: 5.5 -6.5
Density: 1.97 – 2.22 g/cm3
Refractive Index: 1.37 – 1.47 (commonly 1.45)
Color: opal still attached to the host rock can resemble either light or dark opal
Countries of Origin: Australia
Birthstone: April