Takedaite
Chemical formula: Ca<sub>3</sub>B<sub>2</sub>O<sub>6</sub>
Takedaite is a very rare borate mineral, occurring as colorless, small grains in skarn rocks.
Properties
- Luster
- Vitreous
- Streak
- White
- Density
- 3.08
- Cleavage
- None
- Fracture
- Conchoidal
- Transparency
- Transparent
- Crystal system
- Trigonal
Diagnostic features
## Identification Identification of takedaite based on visual characteristics is practically impossible. Its colorless nature and small grain size make it indistinguishable from many other minerals. Reliable identification requires advanced analytical techniques, such as X-ray diffraction (XRD) to determine the crystal structure and chemical analysis (e.g., EDS, WDS) to confirm the composition (presence of calcium, boron, and oxygen). A key clue is its specific environment of occurrence – high-temperature skarns. ## Distinguishing from Similar Minerals Within the host rock, takedaite can be confused with other colorless skarn minerals, such as calcite, spurrite, gehlenite, or quartz. It can be distinguished from calcite by its lack of reaction with hydrochloric acid. Differentiation from other co-occurring minerals requires laboratory methods. ## Crystal Forms Takedaite primarily forms anhedral or poorly developed crystalline grains. Well-formed crystals are extremely rare. It most often occurs as granular aggregates in the rock.
Geological environment
## Genesis Takedaite is a product of high-temperature contact metamorphism. It forms under specific conditions within gehlenite-spurrite skarns, which develop at the contact of magmatic intrusions (e.g., quartz monzonites) with carbonate rocks, such as limestones. ## Mineral Associations This mineral co-occurs with other rare skarn minerals. At the type locality (Fuka mine), it was found in association with calcite, spurrite, gehlenite, rankinite, kilchoanite, oyamalite, suanite, and frolovite. ## Localities The most important and classic locality for takedaite is its type locality – the Fuka mine near Takahashi, Okayama Prefecture, Japan. Its presence has also been confirmed in Russia (Upper Chegem volcanic caldera in the North Caucasus) and Israel (Biran deposit).
Rarity
Very rare
For collectors
## Quality Criteria In the case of takedaite, being a micromineral, collectible value is not based on aesthetics in the traditional sense. The most important criteria are: certainty of species identification (confirmed by analyses), richness of the specimen (number of grains on the matrix), and the presence of rare associated minerals. Specimens with visible, even microscopic, crystal outlines are considered exceptional. ## Popular Localities The most prized specimens by collectors come from the type locality – the Fuka mine in Japan. This locality is known for the occurrence of many rare skarn minerals, which further increases the scientific and collectible value of samples from there.
Care and storage
## Cleaning Takedaite specimens, usually microminerals, should be cleaned with the utmost care. The safest method is to use a soft brush to remove dust. If necessary, compressed air can be used from a safe distance. Contact with water, especially distilled water, should be brief, and the specimen should be thoroughly dried. ## What to Avoid As a borate, takedaite is sensitive to acids, which can damage or completely dissolve it. Ultrasonic cleaners should be avoided, as they can cause cracks in delicate grains. Sudden temperature changes are also not recommended. ## Storage The best way to store specimens is to place them in a sealed "micromount" box, which protects against dust, moisture, and mechanical damage. Precise labeling, including the location and confirmation of mineral identification, is important.