Glauberite
Glauberite is named for the sodium that can help compose its chemistry called “Glauber’s sodium” which will be named after German alchemist Johann Rudolf Glauber (1604–1668). It’s a mineral that forms in saline environments with other evaporite minerals such as halite, Gypsum, Calcite and Thénardite.Glauberite is a relatively rare mineral and a treasure that is extremely unusual. Glauberite gems are curiosities for enthusiasts of the extremely uncommon and uncommon.
Glauberite is often cast or pseudomorphed by other minerals. Pseudomorph means a shape that is”false and occurs when a mineral is replaced by another mineral at such a very slow rate, essentially atom by atom, that no deterioration of the original shape of the crystal does occur. The resulting crystal retains the design associated with original mineral crystal but has the composition of the mineral that is new. A cast occurs when other minerals grow over an existing crystal then an initial crystal completely dissolves, leaving a cast for the form of the crystal that is original. The crystal habit, or shape, of a Glauberite crystal, is unique enough that its pseudomorphs and casts can often be identified to be from a crystal that is glauberite. Glauberite is soluble in water which is why it frequently creates casts.
Notable occurrences of Glauberite include Saline Valley, Inyo County and Searles Lake, San Bernardino County, California; Great Salt Lake, Utah, Texas, New Mexico and Verde Valley, Arizona, United States Of America; Strassfurt, Germany; Russia; Kenya; Chile; Toledo, Spain; Salzburg, Austria; France; Canada; Sicily and Asia. Pseudomorphs and casts come from many of the earlier mentioned localities and from Paterson and Great Notch, New Jersey, USA.
| Category: | Sulfate minerals, anhydrous sulfate subgroup | |||||||||||||||||||||||||
| Chemical Formula: | Na2Ca(SO4)2 | |||||||||||||||||||||||||
| Sodium Calcium Sulfate | ||||||||||||||||||||||||||
| Molecular Weight: | 278.18 gm | |||||||||||||||||||||||||
| Composition: |
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| Crystallography: | Monoclinic – Prismatic |
| Crystal Habit: | Crystals, to 10 cm, tabular on {001}, prismatic along [101] with dominant {111} or along [001] with dominant {110}, or dipyramidal with dominant {111}, {110}; {001} and {111} may be striated k mutual intersections, yielding steplike terminations. |
| Twinning: | None |
| Cleavage: | [001] Perfect, [110] Imperfect |
| Fracture: | Conchoidal |
| Tenacity: | Brittle |
| Moh’s Hardness: | 2.5 – 3.0 |
| Density: | 2.75 – 2.85 (g/cm3) |
| Luminescence: | None |
| Radioactivity: | Not Radioactive |
| Other: | Slightly saline taste; powdery surface alteration in humid environments, leaching Na2SO4 and leaving gypsum. Very slightly soluble in water. |
| Color: | Gray, pale Yellow, Colorless; Colorless in transmitted light |
| Transparency: | Transparent to Translucent |
| Luster: | Vitreous to Waxy; Pearly on {001} cleavage surfaces |
| Refractive Index: | 1.507 – 1.536 Biaxial ( – ) |
| Birefringence: | 0.0220 |
| Dispersion: | Strong; r > v |
| Pleochroism: | X = colorless; Y = colorless |
