Green Opal from Madagascar is a yellow‑green to moss‑green opal with a waxy, earthy texture and subtle internal patterns. Its colour comes mainly from iron, with smaller contributions from vanadium and copper.
Green Opal from Madagascar is a o (opal‑CT) — meaning it’s made of microcrystalline silica containing tridymite and cristobalite, with tridymite usually more abundant. It often includes clay minerals such as saponite, and may contain tiny inclusions of epidote, goethite, and other iron‑bearing minerals.
Appearance & Texture
• Colour: Yellowish‑green to apple‑green, sometimes uneven due to natural spots, lamellae, or cavities.
• Transparency: Translucent to opaque.
• Lustre: Greasy to waxy.
• Patterns: Can show mossy, leafy, or cloudy internal structures; microstructures range from fine microspheres to cauliflower‑like textures.
Physical Properties
• Refractive index: ~1.435–1.460
• Specific gravity: ~2.03–2.07
• UV reaction: Inert under both long‑wave and short‑wave UV.
These values are typical for common opal and help distinguish it from other green minerals.
Formation
Studies suggest Madagascar’s green opal forms under slow to moderate growth conditions, producing its characteristic microstructures and gentle colour zoning.
Uses & Value
Green Opal from Madagascar is appreciated for:
• Carvings, cabochons, spheres, and decorative pieces
• Its calming, earthy aesthetic
