Imayoshiite
Chemical formula: Ca₃Al(CO₃)[B(OH)₄](OH)₆·12H₂O
Imayoshiite is a rare, hydrated calcium aluminum borate-carbonate, forming colorless, hexagonal crystals, belonging to the ettringite group.
Properties
- Mohs hardness
- 2-3
- Luster
- Vitreous
- Streak
- White
- Density
- 1.79
- Cleavage
- on {100}
- Fracture
- Irregular/Uneven
- Transparency
- Transparent
- Crystal system
- Hexagonal
Diagnostic features
## Identification Imayoshiite is identified by its characteristic crystal form – colorless, hexagonal prisms. Key features include low hardness (2-3 on the Mohs scale), low density, and occurrence in a specific geological environment. Final identification requires advanced analytical methods, such as X-ray diffraction (XRD). ## Distinguishing from Similar Minerals It can be confused with other colorless minerals from the ettringite group, such as ettringite itself. Distinguishing them based on visual characteristics is practically impossible and requires specialized studies to determine the chemical composition, especially the boron and carbon content. ## Crystal Forms It forms well-developed, elongated prismatic crystals with a hexagonal cross-section. The crystals are terminated by a pinacoid. It occurs as single crystals or small groups.
Geological environment
## Genesis Imayoshiite is a secondary mineral, formed under low-temperature hydrothermal conditions. At the type locality (Suisho-dani, Japan), it was found in vugs and fissures within serpentinite. ## Mineral Associations This mineral co-occurs with minerals such as calcite, thaumasite, ettringite, and minerals from the serpentine group. ## Localities The only confirmed occurrence of imayoshiite in the world is its type locality: Suisho-dani, Ise City, Mie Prefecture, Japan.
Rarity
Extremely rare
For collectors
## Quality Criteria The most valuable imayoshiite specimens are those with sharp, well-formed, transparent, and undamaged crystals, clearly embedded in a contrasting rock matrix. Due to the small size of the crystals (usually less than 2 mm), their perfect form and clarity are crucial. The presence of associated minerals can enhance the specimen's appeal. ## Popular Localities The only source of imayoshiite specimens is its type locality in Japan, which makes them extremely sought after by collectors specializing in rare minerals or minerals from the ettringite group.
Care and storage
## Cleaning Imayoshiite specimens should be cleaned with the utmost care, using only a soft brush to remove dust. Due to its low hardness and potential reactivity, contact with water, and especially chemicals, should be avoided. ## What to Avoid All acids, detergents, and solvents must be strictly avoided. The mineral is very soft and brittle, susceptible to scratches and mechanical damage. As a hydrated mineral, it can be sensitive to changes in temperature and humidity, which can lead to its dehydration and destruction. ## Storage Imayoshiite specimens should be stored in stable conditions, in closed, padded "micromount" boxes, protecting them from dust, mechanical damage, and sudden changes in humidity. It should be kept away from heat sources and direct sunlight.