Creedite: Chihuahua, Mexico (0.96). Photo © Joel E. Arem, PhD, FGA. Used with permission.
Probably fewer than a dozen creedite gems have ever been faceted. This rare mineral is rarer still as a cuttable crystal. Too soft to wear, this strictly collector’s gem occurs in attractive white, purple, and orange colors.
| Data | Value |
|---|---|
| Name | Creedite |
| Formula | Ca3AI2(SO4)(F,OH)10 • 2H2O. |
| Etymology | After the type locality, Creede Quadrangle, Colorado. |
| Occurrence | Fluorite-rich hydrothermal mineral deposits. |
| Colors | Colorless, white, rose to lilac or purple, orange. |
| Fracture | Conchoidal |
| Hardness | 4 |
| Cleavage | Perfect 1 direction |
| Crystallography | Monoclinic. Crystals short, prismatic; also radial clusters. |
| Refractive Index | 1.461-1.485 |
| Birefringence | 0.024 |
| Dispersion | Moderate |
| Luminescence | Medium white to cream color (SW); bright white to cream (LW). |
| Luminescence Present | Yes |
| Luminescence Type | Fluorescent, UV-Long, UV-Short |
| Absorption Spectrum | Not diagnostic. |
| Optics | a = 1.461; β = 1.478; γ = 1.485. Biaxial (-), 2V = 64°. |
| Optic Sign | Biaxial - |
| Luster | Vitreous. |
| Specific Gravity | 2.71-2.73 |
| Transparency | Transparent to opaque. |
“Creedite,” West Camp, Santa Eulalia, Chihuahua, Mexico, 4.3 x 3.2 x 2.7 cm, amethystine colored crystals. © Rob Lavinsky, www.iRocks.com. Used with permission.
Transparent colorless and purple material from Chihuahua, Mexico has yielded rare facetable creedites. In recent decades, new sources have produced more material in more colors, such as orange.
No known synthetics or enhancements.
The classic source for gemmy material, Santa Eulalia, Chihuahua, Mexico produces crystals up to 1 inch long.
Durango, Mexico has produced stunning, bright orange crystals.
Other notable sources include:
“Creedite,” Abasolo Mine, Navidad, Durango, Mexico, 5.1 x 4.4 x 4.0 cm. © Rob Lavinsky, www.iRocks.com. Used with permission.
Any faceted gems are very small, usually less than 1-2 carats.
You’re more likely to find creedite gems in a mineral collection, if at all, than a jewelry collection. With perfect cleavage and a low hardness of 4, creedites wouldn’t make durable jewelry stones. A sensitivity to acid makes it inadvisable to wear or handle these gems for long periods. See our gemstone jewelry care guide for cleaning recommendations.
“Creedite,” Akchatau Mine, Karaganda Oblast, Kazakhstan, 3.2 x 2.3 x 1.9 cm. © Rob Lavinsky, www.iRocks.com. Used with permission.
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