CROCOITE: Dundas, Tasmania (3.4)
Crocoite is one of the loveliest of all collector stones. It's too soft and brittle for wear, but it is quite a rare mineral and relatively few stones have been cut. The dispersion is high but completely masked by the intense body color.
Crocoite Value
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Crocoite Information
| Data | Value |
| Name | Crocoite |
| Crystallography | Monoclinic. Crystals prismatic, sometimes hollow. |
| Colors | Red-orange, cherry red. orange, yellowish. |
| Luster | Adamantine to vitreous. |
| Hardness | 2.5-3 |
| Density | 5.9-6.1 |
| Birefringence | 0.270 |
| Cleavage | Indistinct. Brittle. |
| Dispersion | Strong |
| Stone Sizes | Gems can be up to about 10 carats, but these are usually not transparent. Clean stones up to 1-2 carats are available in deep red-orange color from Tasmania. Devonian Group (Calgary, Alberta, Canada): 14.5 (orange, Tasmania). Smithsonian Institution (Washington, D.C): 5.7 (orange-red, Tasmania). |
| Luminescence | Weak reddish to dark brown (SW); weaker effect in LW. |
| Spectral | Distinct band at 5550 but seen only in thin fragments. Transmits mainly in the yellow-red region of the spectrum. |
| Formula | PbCrO4 |
| Pleochroism | Orange-red to blood red. |
Streak: Orange-yellow.
Optics: a= 2.29-2.31; β = 2.36; γ = 2.66.
Biaxial (+), 2V= 57°.
Occurrence: Secondary mineral in oxidized zones of lead deposits.
Dundas, Tasmania: best crystals found in the world, some gemmy; large clusters.
Beresov District, USSR: red crystals.
Tiger, Arizona: very tiny crystals.
California; Minas Gerais, Brazil
Comments: Crocoite is one of the loveliest of all collector stones. It’s too soft and brittle for wear, but it is quite a rare mineral and relatively few stones have been cut. The dispersion is high but completely masked by the intense body color.
Name: From the Greek krokos, meaning saffron, in allusion to the color.
 | Destructive Gemstone Tests: Streak Testing |
