Boulder Opal
Australia
16.32 carats
© gemselect.com
It is a Precious Opal that is embedded in the sandstone or ironstone matrix and routinely cut with it as part of the gem.
Each piece is unique, that is why it can't be used for mass produced jewelry.
Boulder 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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Boulder Opal Gemstones by Size
This table shows distribution of Boulder 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:2.17 cts
Heaviest:206.2 cts
Average:24.33 cts
Total photos:49
Do you have a larger Boulder Opal? Why not upload a photo?
| General Information | |||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| A variety or type of: | Precious Opal, which is a variety of Opal | ||||||||||||||||||||||||
| Chemical Formula |
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| Physical Properties of Boulder Opal | |||||||||||||||||||||||||
| Mohs Hardness | 5 to 6.5, Blue Chart Gem Identification (2010) | ||||||||||||||||||||||||
| Specific Gravity | 1.98 to 2.25, Blue Chart Gem Identification (2010) | ||||||||||||||||||||||||
| Tenacity | Brittle, Gemstones of the world (2001) | ||||||||||||||||||||||||
| Cleavage Quality | None, Gemstones of the world (2001) | ||||||||||||||||||||||||
| Fracture | Conchoidal, Gemstones (2009) | ||||||||||||||||||||||||
| Optical Properties of Boulder Opal | |||||||||||||||||||||||||
| Refractive Index | 1.370 to 1.470, Blue Chart Gem Identification (2010) | ||||||||||||||||||||||||
| Optical Character | Isotropic, Gemstones (2009) | ||||||||||||||||||||||||
| Birefringence | None, Gemstones of the world (2001) | ||||||||||||||||||||||||
| Pleochroism | Absent, Gemstones of the world (2001) | ||||||||||||||||||||||||
| Dispersion | None, Gemstones of the world (2001) | ||||||||||||||||||||||||
| Colour | |||||||||||||||||||||||||
| Colour (General) | Dark base surface, play-of-color, Gemstones of the world (2001) | ||||||||||||||||||||||||
| Transparency | Transparent,Translucent,Opaque, Gemmological Tables (2004) | ||||||||||||||||||||||||
| Lustre | Vitreous, Gemstones (2009) | ||||||||||||||||||||||||
| Crystallography of Boulder Opal | |||||||||||||||||||||||||
| Crystal System | Amorphous, Blue Chart Gem Identification (2010) | ||||||||||||||||||||||||
| Habit | Massive, Gemstones (2009) | ||||||||||||||||||||||||
| Geological Environment | |||||||||||||||||||||||||
| Where found: | Occurs as patches, seams, blobs, or thin veins in ironstone concretions., Opal (2007) | ||||||||||||||||||||||||
| Further Information | |||||||||||||||||||||||||
| Mineral information: | Boulder Opal information at mindat.org | ||||||||||||||||||||||||
| Significant Gem Localities | |||||||||||||||||||||||||
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