Rob Lavinsky, iRocks.com – CC-BY-SA-3.0 [CC-BY-SA-3.0], via Wikimedia Commons
This mineral is very hard to cut because of extreme softness and cleavage. Gaylussite dries out slowly in air and the surfaces may turn white. Stones in collections are therefore best stored in sealed containers to prevent dehydration. Gaylussite is seen only in very comprehensive collections, and relatively few stones have been cut. Transparent crystals are not terribly rare, but faceted gems are relatively uninteresting.
Gaylussite Value
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Gaylussite Information
| Data | Value |
| Name | Gaylussite |
| Crystallography | Monoclinic. Crystals elongated, flattened, and wedge-shaped. |
| Colors | Colorless, white, grayish, yellowish. |
| Luster | Vitreous |
| Hardness | 2.5-3 |
| Density | 1.995 |
| Birefringence | 0.077 |
| Cleavage | Perfect 1 direction. Fracture conchoidal. Brittle. |
| Stone Sizes | Crystals from Searles Lake have been found up to 2 inches long. Gems cut from such crystals could be up to about 20-30 carats. |
| Luminescence | Weak cream white in SW (Nevada). May be triboluminescent. |
| Spectral | Not diagnostic |
| Formula | Na2Ca(CO3) ·5H2O |
| Pleochroism | None |
Optics: a = 1.445;β= 1.516; γ= 1.522.
Biaxial (-), 2V = 34°
Occurrence: In alkaline lakes or evaporite deposits rich in borax.
California: Searles Lake, Owens Lake, China Lake. Borax Lake.
Wyoming; Nevada.
Mongolia, China.
Venezuela: in clay beds.
Kenya: in transparent crystals, from Lake Amboseli.
Comments: This mineral is very hard to cut because of extreme softness and cleavage. Gaylussite dries out slowly in air and the surfaces may turn white. Stones in collections are therefore best stored in sealed containers to prevent dehydration. Gaylussite is seen only in very comprehensive collections, and relatively few stones have been cut. Transparent crystals are not terribly rare, but faceted gems are relatively uninteresting.
Name: After the eminent French chemist, Professor L. J. Gay-Lussac.
