AllMineralsRock
Opal
Opal is a very popular gemstone composed of silicon dioxide. [1]
Opal: Quick Facts and Characteristics
Some quick facts for Opal:- Transparency: Opal can be translucent or transparent.
- Luster: In terms of luster, opal can be pearly, vitreous (glassy) or waxy.
- Streak: Opal streaks white.
- Specific Gravity: Opal's specific gravity ranges from 1.98 to 2.25.
Opal: Background and Summary
Opal is a mineraloid that is formed from the silica-rich water that permeates through the earth's crust. It is a beautiful gemstone that is known for its unique play of colors. Opal is a non-crystalline mineral that is made up of tiny spheres of silica, which diffract light in a way that creates a rainbow of colors. The colors of opal can range from white, gray, and black to red, orange, yellow, green, blue, and purple.Identifying opal can be a bit tricky as it can look like other minerals such as quartz, chalcedony, and agate. However, there are a few characteristics that can help you identify opal. Firstly, opals are usually quite soft and can be scratched easily, so if you scratch the surface and it leaves a mark, it's not opal. Secondly, opals have a unique play of colors that can be seen when you move them around in the light. Finally, opals are often found in association with other minerals such as ironstone, sandstone, and basalt.
Opal has been used in jewelry for centuries and is highly valued for its unique beauty. It is often used in rings, necklaces, earrings, and other types of jewelry. Opal is also used in the production of glass, ceramics, and electronics. Opal is believed to have healing properties and is used in crystal healing to promote emotional stability and calmness.
Opal: Table of Properties
| Attribute | Opal (src) |
|---|---|
| Transparency | transparent, translucent |
| Chemical Formula | SiO2· nH2O |
| Chemical Composition | silicon dioxide |
| Specific Gravity | 1.98, 2.25 |
| Streak | white |
| Hydrous | Yes |
| Colors | common: red sometimes: blue, gray, pink, black, brown, green, white, orange, purple, yellow, colorless, band, multicolor |
| Solubility | Soluble in hot salt water, bases, HF |
| Birefringence | none |
Opal: FAQ
Q: Is opal a rare gemstone?A: Yes, opal is considered a rare gemstone.
Q: Can opal be found all over the world?
A: Yes, opal can be found in many countries including Australia, Ethiopia, Mexico, and the United States.
Q: Is opal a durable gemstone?
A: Opal is relatively soft and can be easily scratched or chipped. It is important to handle opals with care and avoid exposing them to extreme temperatures or chemicals.
Sources
- Gemological Institute of America (GIA)- International Gem Society (IGS)
- Opal: https://en.wikipedia.org/wiki/Opal
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