Korzhinskite
Chemical formula: CaB<sub>2</sub>O<sub>4</sub>·0.5H<sub>2</sub>O
Korzhinskite is a rare hydrated calcium borate, forming colorless, fibrous aggregates and tabular crystals.
Properties
- Mohs hardness
- 3
- Luster
- Vitreous
- Streak
- White
- Density
- 2.49
- Cleavage
- Perfect on {010}
- Fracture
- Uneven
- Transparency
- Transparent to translucent
- Crystal system
- Orthorhombic
Diagnostic features
## Identification Field identification of korzhinskite is practically impossible. In a collection, it is recognized by its characteristic habit – white, fibrous or felted aggregates, as well as small, tabular crystals. Association with the locality and accompanying minerals, especially other borates, is key. ## Distinguishing from Similar Minerals It can be confused with other white, fibrous secondary minerals, such as ulexite, colemanite, or gypsum. Ulexite often exhibits a "television effect" (image conduction), which korzhinskite does not possess. Gypsum is significantly softer (hardness 2). Final distinction from other rare borates requires advanced analytical methods, such as X-ray diffraction (XRD). ## Crystal Forms Crystals are very small, usually less than 1 mm in size. They take the form of thin tablets or blades. Most often, they occur as dense, tangled fibrous aggregates or radial clusters.
Geological environment
## Genesis Korzhinskite is a hydrothermal mineral, formed as a result of metasomatic interaction of boron-rich solutions with carbonate rocks (limestones, marbles) in contact zones with magmatic intrusions. It forms in magnesian and calcic skarns. ## Mineral Associations It most commonly co-occurs with other borate minerals, such as ludwigite, kotoite, szaibelyite (ascharite), as well as with calcite, dolomite, magnetite, fluorite, and minerals from the serpentine group. ## Localities The most important and classic occurrences of this mineral are in Russia, particularly in the Tayozhnoye deposit (Iron Ridge) in Eastern Siberia, which is its type locality. It has also been reported in skarns in Romania (Băița Bihor) and in China (iron and boron ore mine in Liaoning).
Rarity
Rare
For collectors
## Quality Criteria The most prized korzhinskite specimens are those that possess well-formed, even if microscopic, crystals, preferably forming radial aggregates on a contrasting rock matrix. Rich co-occurrence with other rare borates is also important, as it enhances the scientific and aesthetic value of the specimen. Due to the nature of the mineral, the clarity and transparency of individual crystals are less important than the overall form and richness of the aggregate. ## Popular Localities Specimens from the type locality in Russia (Tayozhnoye deposit) are by far the most sought after by collectors. Material from other localities, such as Romania or China, is much less commonly found on the collector's market.
Care and storage
## Cleaning Korzhinskite specimens are very delicate and potentially sensitive to water. Wet cleaning should be avoided. A soft brush or carefully applied compressed air from a safe distance can be used to remove dust. ## What to Avoid Contact with water, acids, and other chemicals that can dissolve or damage the mineral must be strictly avoided. Due to its low hardness, it is very susceptible to mechanical damage. It should be protected from shocks, drops, and scratches. ## Storage Korzhinskite specimens are best stored in tightly sealed "micromount" containers, which protect them from dust, humidity, and physical damage. Store in a dry place, away from sources of vibration.