Earth Record
Mineralogy and formation
Variety of Fluorite
A composite so complex that geologists argue about what to call it. Tiffany stone is a purple, lavender, and white opalized fluorite breccia from the Brush Wellman beryllium mine in Spor Mountain, Utah, the only known source. It contains fluorite, opal, chalcedony, dolomite, bertrandite, and quartz in a matrix so mineralogically diverse that different labs may emphasize different phases depending on which section they analyzed.
The purple comes from fluorite. The waxy zones are opal. The white areas are often dolomite or chalcedony. It formed in volcanic tuff that was mineralized by beryllium and fluorine-bearing hydrothermal fluids. Since it comes exclusively from a beryllium mine with restricted access, supply depends entirely on byproduct recovery from industrial mining operations. When the mine closes or shifts focus, new material will not exist.
Chemical FormulaBertrandite + Opal + FluoriteCrystal SystemMixedMohs Hardness4Specific Gravity2.30-2.50LusterVitreous to waxyColorPurple-WhiteIMA StatusvarietyIMA NumberNone (variety of Fluorite, which is IMA-grandfathered pre-1959) USA (Utah)
Telling it apart
Tiffany stone is a composite mineral assemblage of fluorite, opal, bertrandite, chalcedony, quartz, calcite, dolomite, and manganese oxides from a single source: the Brush Wellman beryllium mine in the Thomas Range, Utah. The mine processes bertrandite for beryllium extraction and tiffany stone is a byproduct, which means supply is controlled by industrial mining operations, not gem mining.
The purple (from fluorite and manganese), white (from opal and chalcedony), and cream zones create a distinctive appearance, but the material has no standardized identity and properties vary by zone. Fluorite-dominant areas are soft (Mohs 4) with octahedral cleavage; chalcedony areas are harder (6. 5 to 7). The composite nature means hardness varies within a single specimen. Specific gravity runs 2.
30 to 2. 50. Other purple-and-white composite stones from different localities are sometimes marketed as tiffany stone, but the name should properly apply only to the Utah material. Under magnification, the purple zones show fluorite's cubic crystal structure, the white zones show the amorphous texture of opal, and the two intergrade in a pattern unique to this specific deposit. The beryllium content in bertrandite zones means rough material should be handled with standard mineral safety precautions.
Spotting the real thing
Swirl Pattern Complexity Genuine tiffany stone displays complex, non-repeating swirl patterns where purple, lavender, white, and cream phases interpenetrate organically. No two specimens are alike. Dyed or synthetic imitations tend to show more uniform or repetitive color distribution. Look for the chaotic, geological randomness of real mineral intergrowth, the patterns should look like they happened slowly, over millions of years, because they did.
Multiple Mineral Phases Under close examination (10x loupe), genuine tiffany stone reveals distinct mineral phases, glassy opal zones, crystalline fluorite areas, and sometimes visible chalcedony banding. The transitions between phases are gradual and interpenetrating, not sharp. Imitations made from dyed agate or polymer-impregnated materials show more uniform texture throughout.
The multi-phase nature is tiffany stone's fingerprint. Hardness Variation Because tiffany stone contains minerals ranging from Mohs 4 (fluorite) to Mohs 6. 5 (chalcedony), a single specimen shows variable hardness across its surface.
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