Ezcurrite
Chemical formula: Na<sub>2</sub>B<sub>5</sub>O<sub>7</sub>(OH)<sub>3</sub>·2H<sub>2</sub>O
Ezcurrite is a rare, colorless or white sodium borate, forming fibrous or chalky aggregates in borate deposits.
Properties
- Mohs hardness
- 2.5
- Luster
- Vitreous
- Streak
- White
- Density
- 2.39
- Cleavage
- Perfect on {100}
- Fracture
- Splintery
- Transparency
- Transparent
- Crystal system
- Monoclinic
Diagnostic features
## Identification Ezcurrite is most often identified by its mode of occurrence – as white, soft, fibrous, or chalk-like masses. Its low hardness (around 2.5) and lightness are also characteristic. Its occurrence in the specific environment of borate evaporites is a key indicator. ## Distinguishing from Similar Minerals Ezcurrite can be confused with other white, fibrous borate minerals, such as ulexite or kernite, as well as fibrous gypsum. It is distinguished from ulexite by the absence of the characteristic "television stone" effect. It differs from kernite in form (kernite forms larger, more defined crystals) and optical properties. It is distinguished from gypsum by its environment of occurrence and chemical tests for the presence of boron. ## Crystal Forms The mineral forms elongated, acicular, or bladed crystals, which almost always occur as matted, fibrous, or radiating aggregates. Massive or earthy aggregates are less common.
Geological environment
## Genesis Ezcurrite is a sedimentary mineral, formed by the evaporation of saline lake waters rich in boron. It forms under dry climatic conditions in sedimentary basins where the concentration of borates reaches an appropriate level. It is a product of the late stage of brine crystallization. ## Mineral Associations This mineral occurs in association with other borates, such as borax, kernite, ulexite, as well as halite and gypsum. Co-occurrence with these minerals is typical of its genetic environment. ## Localities The only known and confirmed occurrence of ezcurrite in the world is the Tincalayu mine, in the Salar del Hombre Muerto region, Salta Province, Argentina. This is its type locality.
Rarity
Extremely rare
For collectors
## Quality Criteria The quality of an ezcurrite specimen is primarily judged by the abundance and purity of its white, fibrous aggregates. The most desirable samples are those with clearly visible, silky aggregates on a rock matrix, contrasting with it. Due to its rarity, any authentic specimen, even a small one, is considered valuable. It is important that the specimen is well-preserved and undamaged. ## Popular Localities The only source of ezcurrite specimens is its type locality – the Tincalayu mine in Argentina. All samples available on the collector's market originate from this single location.
Care and storage
## Cleaning Ezcurrite is very delicate and sensitive to water. It should not be washed with water, as it may partially dissolve or be damaged. To remove dust, a very soft, dry brush or a photographic air blower can be carefully used to dislodge loose particles. ## What to Avoid Contact with water and all liquids, including cleaning agents, must be strictly avoided. The mineral is very soft, susceptible to scratching and crumbling. It should be protected from high humidity, which can cause its degradation. Do not expose to high temperatures. ## Storage Ezcurrite specimens should be stored in a dry place, preferably in a sealed container (e.g., a "perky box") away from sources of moisture. Due to its fragility, it should be avoided to place it near other minerals that could mechanically damage it.