Opal
What is Opal?
Opal is a hydrated amorphous form of silica that is known for its stunning play-of-color. It’s primarily found in Australia, but it can also be sourced from other countries including Ethiopia and Mexico. Opal is often used as a gemstone and is a popular choice for jewelry due to its beautiful colors and spiritual significance.
Opal is a colorful gemstone known for its unique play-of-color. Its wide range of colors and intricate patterns make it a popular choice for jewelry and decorative items. The stone is often used in rings, necklaces, and pendants, and is sometimes used to make beads.
| Chemical Classification | Inorganic - Silicate (Hydrated silica) |
| Color | Opals can be colorless, white, gray, red, orange, yellow, green, blue, magenta, rose, pink, slate, olive, or brown. The play-of-color can display a wide range of hues. |
| Streak | White to Light Blue |
| Luster | Subvitreous to waxy. |
| Transparency | Translucent to opaque. |
| Occurrence | Australia, Ethiopia, and Mexico. |
| Formation | Typically found in sedimentary rocks, but can also be found in volcanic rocks. |
| Diaphaneity | Translucent to opaque with play-of-color |
| Cleavage | Conchoidal |
| Mohs Hardness | 5.5-6.5. |
| Specific Gravity | Approximately 1.98 to 2.25. |
| Diagnostic Properties | Play-of-color. |
| Chemical Composition | SiO2·nH2O |
| Pleochroism | None. |
| Crystal System | Amorphous |
| Optical Properties | Isotropic (due to its amorphous nature) |
| Refractive Index | 1.440 - 1.460 |
| Birefringence | None (isotropic due to amorphous nature) |
| 2V angle | Not applicable (amorphous) |
| Dispersion | Not typically relevant for opals due to their play-of-color. |