mineral

Goldstone

Avventurina (Cu + SiO2 glass)

Hardness: 5.5-6 on Mohs scale; Color: Reddish-brown with metallic gold flecks; Luster: Vitreous to sub-metallic; Crystal Structure: Amorphous (glass); Cleavage: None/Conchoidal fracture; Specific Gravity: Approx 2.5-2.8

Hardness: 5
Color: Reddish-brown with metallic gold flecks
Luster: Vitreous to sub-metallic

Identified April 8, 2026More mineral →

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Physical properties

Formation & geological history

Goldstone is a human-made material. It originated in 17th-century Venice, Italy, through a process of melting silica, copper oxide, and other metal oxides in a low-oxygen environment. When cooled slowly, the copper ions form tiny metallic crystals, creating the signature 'schiller' or glitter effect.

Uses & applications

Primarily used for lapidary work, jewelry (beads, cabochons), carvings, decorative ornaments, and metaphysical collecting.

Geological facts

Legend says it was discovered by Italian monks who accidentally dropped copper filings into molten glass, though it was likely an invention of the Miotti family in Venice. Despite its name, it contains no actual gold; the 'gold' flakes are copper.

Field identification & locations

Identify by its uniform, intense glitter (aventurescence) and smooth, glass-like texture. In the field, it is rarely found in its natural state as it is synthetic, but specimens are often found tumbled or polished in rock shops. Note the lack of natural crystal grain compared to natural aventurine quartz.