CERULEITE: Arizona (specimens each, ~1 inch across)
Ceruleite is a little-known gem material of truly exquisite color. It takes a very high polish easily and quickly, and the color of the polished gems is far deeper than that of the rough nodules. It is extremely rare in fine, solid, cuttable pieces and consequently is rather expensive. Few cut stones are to be seen in museum collections, and the total amount of fine Bolivian material may not exceed several hundred pounds. A major problem with ceruleite is porosity, rendering the material too soft and fragile for cutting and wear. This problem can be solved by plastic impregnation. Such impregnated ceruleite has a density of 2.58.
Ceruleite Value
The International Gem Society (IGS) has a list of businesses offering gemstone appraisal services.
Ceruleite Information
| Data | Value |
| Name | Ceruleite |
| Crystallography | Usually massive, compact, earthy |
| Colors | Turquoise-blue shades, cerulean blue. |
| Luster | Earthy, dull |
| Hardness | 6.5 (conflicting data, may be softer) |
| Density | 2.7 – 2.8 |
| Stone Sizes | Nodules are usually small, less than 1 inch and up to several inches in size. The material yields cabochons only. |
| Formula | Cu2Al2(AsO4)4(OH)13 |
OPTICS: Mean index ~1.60. Very fine grained.
OCCURRENCE: Sedimentary material formed in the vicinity of copper deposits, like turquoise.
Cornwall, England
Huanaco, Chile: original material.
Southern Bolivia: cabbing material of fine color.
COMMENTS: Ceruleite is a little-known gem material of truly exquisite color. It takes a very high polish easily and quickly, and the color of the polished gems is far deeper than that of the rough nodules. It is extremely rare in fine, solid, cuttable pieces and consequently is rather expensive. Few cut stones are to be seen in museum collections, and the total amount of fine Bolivian material may not exceed several hundred pounds. A major problem with ceruleite is porosity, rendering the material too soft and fragile for cutting and wear. This problem can be solved by plastic impregnation. Such impregnated ceruleite has a density of 2.58.
NAME: In allusion to its color; the Latin caerulea means sky blue.
