Hydroglauberite
Chemical formula: Na₁₀Ca₃(S⁶⁺O₄)₈·6H₂O
Hydroglauberite is a rare, hydrated sodium and calcium sulfate, forming small, colorless crystals, found in lake sediments.
Properties
- Mohs hardness
- 2.5
- Color
- White
- Luster
- Vitreous
- Streak
- White
- Density
- 1.510
- Cleavage
- Three noted, one of which is parallel to elongation
- Fracture
- Uneven
- Transparency
- Translucent
- Crystal system
- Monoclinic
Diagnostic features
## Identification Identifying hydroglauberite under amateur conditions is practically impossible. It requires advanced analytical methods such as X-ray diffraction (XRD) and chemical analysis (EDS/WDS). Its key diagnostic feature is its solubility in water and its occurrence in a specific evaporitic environment. ## Distinguishing from Similar Minerals It can be confused with other colorless, soluble sulfates found in similar parageneses, such as mirabilite, thenardite, gypsum, or glauberite. Distinguishing it from these requires specialized laboratory tests. The crystal habit (fine blades and needles) can be an indication, but it is not a uniquely identifying feature. ## Crystal Forms It forms small, bladed or acicular crystals, often gathered in radial or chaotic aggregates. Crystals rarely reach a size that allows for observation of details with the naked eye.
Geological environment
## Genesis Hydroglauberite is a mineral of evaporitic origin. It forms as a result of precipitation from saline lake waters (brines) in a dry and cold climate. It crystallizes directly from solution or as a result of transformations of other, previously formed salt minerals. ## Mineral Associations It most often co-occurs with other evaporite minerals, such as glauberite, astrakhanite (bloedite), thenardite, mirabilite, gypsum, and halite. These minerals together form characteristic assemblages in salt deposits. ## Localities The most important and classic localities for this mineral are saline lakes in Russia, especially Lake Kuchuk (Kuczuk) in Altai, from which the type material originates. It has also been reported in the sediments of Great Salt Lake in Utah, USA.
Rarity
Very rare
For collectors
## Quality Criteria The collectible appeal of hydroglauberite is very specific and mainly concerns micromounts. The most prized specimens are those with well-formed, sharp, transparent crystals, forming rich groups on a small rock matrix. Due to the microscopic size of the crystals, clarity and color are not key criteria – the quality and richness of crystallization visible under magnification are paramount. ## Popular Localities The only sources of collectible specimens are essentially two localities: Lake Kuchuk in Russia and the Great Salt Lake region in Utah, USA. Specimens from both these locations are equally rare and sought after by collectors specializing in evaporite minerals or rare species.
Care and storage
## Cleaning Hydroglauberite specimens are extremely sensitive to water and moisture. Mechanical cleaning is the only permissible method and must be carried out with the utmost care, dry, using a very soft brush. Any contact with water, even distilled, will dissolve the mineral. ## What to Avoid Absolutely avoid contact with water, water vapor, and all liquids. The mineral is soluble in water. It should be protected from high air humidity, which can lead to its slow degradation. It is a very soft and brittle mineral, sensitive to any impacts and scratches. ## Storage Storage requires ensuring dry conditions. It is best to place the specimen in a sealed, closed "perky box" with a desiccant (e.g., silica gel). Display should only take place in enclosed display cases with controlled humidity.