mineral

Tiffany Stone

Bertrandite (with Fluorite, Opal, and Chalcedony), Be4Si2O7(OH)2

AI-generated identification · may be incorrect

Hardness: 5 to 7 (variable); Color: Purple, violet, white, and cream; Luster: Vitreous to waxy; Crystal structure: Amorphous (opal) to Orthorhombic (bertrandite); Cleavage: None; Specific gravity: Approx 2.1-2.5

Hardness: 5 to 7 (variable)
Color: Purple, violet, white, and cream
Luster: Vitreous to waxy

Identified April 22, 2026More mineral →

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Physical properties

Formation & geological history

Formed through the hydrothermal alteration of fluorite nodules in volcanic ash tuff layers. Primarily found in the Brush Wellman beryllium mine in Utah, USA, dating to the Cenozoic era.

Uses & applications

Primarily used as a major source of Beryllium for aerospace and electronics; highly valued by lapidaries and collectors for jewelry making (cabochons).

Geological facts

Also known as 'Ice Cream Opal' or 'Purple Opal,' it is one of the rarest stones in the world because it is found almost exclusively at one single location: Spor Mountain in western Utah.

Field identification & locations

Identify by its distinctive swirling purple and white patterns and conchoidal fracture. In the field, look for 'nodules' within white or grey volcanic tuff; it is often found as a byproduct of beryllium mining.