Black Opal (Triplet)

Hardness: 5.5-6.5 (Mohs scale), Color: Vivid play-of-color (blue, green), Luster: Vitreous to waxy, Structure: Amorphous (microscopic silica spheres)

Formed from silica-rich water seeping into cracks and cavities in sedimentary or volcanic rocks. Most precious opal is recovered from Australian sedimentary basins (Cretaceous age).

Primarily used in jewelry as cabochons, pendants, and rings. Triplet opals are manufactured to provide a high-end look at a lower cost.

Opals are non-crystalline minerals called mineraloids. Black opals are the rarest and most valuable; however, triplets consist of a thin slice of opal glued between a dark backing and a clear quartz or glass cap.

Identify for multi-layer structure from the side view. High-quality triplets are found in jewelry stores worldwide, with major mining original sources in lightning Ridge, Australia.