mineral

Bacan Stone (Chrysocolla-in-Chalcedony)

Chrysocolla in Chalcedony (SiO2 with (Cu, Al)2H2Si2O5(OH)4·nH2O)

Hardness: 6.5-7 (Mohs scale); Color: Bluish-green to vivid green; Luster: Vitreous to waxy; Structure: Microcrystalline; Translucent to opaque.

Hardness: 6
Color: Bluish-green to vivid green
Luster: Vitreous to waxy

Identified May 23, 2026More mineral →

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Physical properties

Hardness: 6.5-7 (Mohs scale); Color: Bluish-green to vivid green; Luster: Vitreous to waxy; Structure: Microcrystalline; Translucent to opaque.

Formation & geological history

Formed through the infiltration of copper-rich solutions into cryptocrystalline silica (chalcedony) in the secondary enrichment zones of copper deposits. Famous specimens come from Kasiruta Island, Indonesia.

Uses & applications

Primarily used as a gemstone for rings (akik), pendants, and high-end collector cabochons, especially in Southeast Asia.

Geological facts

Commonly known in Indonesia as 'Batu Bacan.' It is famous for its ability to 'change' or evolve in clarity and color over time with wear, a process local collectors call 'metamorphosis.'

Field identification & locations

Identify by its unique 'electric' bluish-green glow when backlit and high hardness compared to pure chrysocolla. Mostly found in the North Maluku region of Indonesia.

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