About Opal
A hydrated amorphous form of silica, prized for its unique play-of-color (opalescence) in precious varieties. It's an emotional stone, amplifying feelings, enhancing creativity, and encouraging spontaneity and freedom. (A mineraloid).
Primary Hues
Colorless, White, Yellow, Red, Orange, Green, Blue, Brown, Black, with play-of-color (opalescence)
Geological & Scientific Details
Opal is classified as a mineraloid mineral which typically crystallizes in the amorphous[2] system. Its chemical formula is Hydrated silica. SiO2·nH2O. Common crystal habits include irregular veins, in masses, in nodules.
Key Geological Properties:
- Mineral Category: Mineraloid
- Chemical Formula: Hydrated silica. SiO2·nH2O
- IMA Symbol: Opl[1]
- Crystal System: Amorphous[2]
- Predominant Geological Color: Colorless, white, yellow, red, orange, green, brown, black, blue, pink
- Crystal Habit: Irregular veins, in masses, in nodules
- Cleavage: None[2]
- Luster: Subvitreous to waxy[2]
- Streak: White
- Diaphaneity: opaque, translucent, transparent
Associated Minerals
- Opal
- Common Opal
- Precious Opal
- Fire Opal
- Boulder Opal
- Black Opal
- Hyalite