Common Opal
Hydrophane
Ethiopia
1.50 carats
© Kosnar Gem Co.
Common Opal Gemstones by Colour
This table shows the variety of hues this gemstone can be found in. Click on a photo for more information.
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Common Opal Gemstones by Size
This table shows distribution of Common Opal gemstone sizes that are listed on this site. This can give a good indication as to the general availability of this gemstone in different sizes.
Contributed photos
Lightest:0.96 cts
Heaviest:28.87 cts
Average:4.52 cts
Total photos:30
Do you have a larger Common Opal? Why not upload a photo?
| General Information | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| A variety or type of: | Opal | |||||||||
| Varieties/Types: | Agate Opal - Opal showing concentric banding as in agate. Andean Opal - A greenish-blue variety of opal found in Peru. Girasol - Bluish-white translucent Opal with reddish reflections. Honey Opal - An orange-brown Common opal. Hyalite - Colourless, water-clear opal with a strong sheen. Hydrophane - A milky variety of Opal that turns translucent or transparent when immersed in water. Jasper Opal - A brecciated Jasper cemented by opal. Milk Opal - A white Common opal. Moss Opal - Milky opal containing dendritic inclusions Prase Opal - A green variety of Common opal. Semiopal - Historic name for an opal without opalescence Wax Opal - A yellow-to brown Opal with a waxy lustre. Wood Opal - Petrified wood replaced with Opal. | |||||||||
| Chemical Formula |
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| Physical Properties of Common Opal | ||||||||||
| Mohs Hardness | 5.5 to 6.5, Gemstones of the world (2001) | |||||||||
| Specific Gravity | 1.98 to 2.50, Gemstones of the world (2001) | |||||||||
| Tenacity | Brittle, Gemstones of the world (2001) | |||||||||
| Cleavage Quality | None, Gemstones of the world (2001) | |||||||||
| Fracture | Conchoidal,Splintery, Gemstones of the world (2001) | |||||||||
| Optical Properties of Common Opal | ||||||||||
| Refractive Index | 1.37 to 1.52, Gemstones of the world (2001) | |||||||||
| Birefringence | None, Gemstones of the world (2001) | |||||||||
| Pleochroism | Absent, Gemstones of the world (2001) | |||||||||
| Dispersion | None, Gemstones of the world (2001) | |||||||||
| Colour | ||||||||||
| Colour (General) | All colours, Gemstones of the world (2001) | |||||||||
| Transparency | Translucent,Opaque, Gemstones of the world (2001) | |||||||||
| Crystallography of Common Opal | ||||||||||
| Crystal System | Amorphous, Gemstones of the world (2001) | |||||||||
| Habit | Kidney- or grape-shaped aggregates, Gemstones of the world (2001) | |||||||||
| Further Information | ||||||||||
| Mineral information: | Common Opal information at mindat.org | |||||||||