Misakiite

Chemical formula: Cu<sup>2+</sup><sub>3</sub>Mn<sup>2+</sup>(OH)<sub>6</sub>Cl<sub>2</sub>

Misakiite is an extremely rare copper and manganese hydroxychloride, forming green, hexagonal crystals.

## Characteristics Misakiite is a secondary mineral from the halide group. It forms small, hexagonal, prismatic crystals, often occurring as radial or subparallel aggregates. Its color ranges from green to blue-green. It is a transparent to translucent mineral with a vitreous luster. Due to its rarity and small crystal size, specimens are typically micromounts. ## Physical Properties The hardness of misakiite has not yet been determined. The mineral is characterized by a vitreous luster and a light green streak. Its calculated density is 3.43 g/cm³. It exhibits perfect cleavage in one direction. ## Colors and Varieties The mineral occurs in shades from green to blue-green. No color varieties or commercial varieties have been identified. ## History and Name Misakiite was recognized as a new mineral by the International Mineralogical Association (IMA) in 2013 (IMA2013-128). Its name comes from its discovery locality – Cape Misaki on Sado Island, Niigata Prefecture, Japan. It was described by a team of Japanese mineralogists led by Satoshi Matsubara. ## Applications As an extremely rare mineral, misakiite has no industrial applications. It is of purely scientific and collector's interest.

Properties

Luster
Vitreous
Streak
Light green
Density
3.43
Cleavage
Perfect on {0001}
Fracture
Uneven
Transparency
Translucent
Crystal system
Trigonal

Diagnostic features

## Identification Characteristic features of misakiite include its green or blue-green color, hexagonal crystal habit, and occurrence in radial aggregates. Its geological environment is also key – as a secondary mineral in altered volcanic rocks. ## Distinguishing from similar minerals Misakiite can be confused with other green secondary copper minerals, such as atacamite, clinoatacamite, or paratacamite. Definitive differentiation requires advanced analytical methods, such as X-ray diffraction (XRD), which confirms its unique, trigonal crystal structure. Co-occurrence with anthonite can be an additional diagnostic clue. ## Crystal forms Misakiite crystals have a hexagonal prismatic habit. They are usually small and form fan-shaped, radial, or subparallel clusters and aggregates.

Geological environment

## Genesis Misakiite is a secondary mineral. It forms in the oxidation zone of copper deposits. At the type locality, it was found in quartz veins cutting andesitic tuffs and tuff breccias. ## Mineral associations This mineral co-occurs with other secondary copper minerals, such as atacamite, clinoatacamite, anthonite, and calumetite, as well as with gypsum and quartz. ## Localities The only confirmed locality for misakiite worldwide is its type locality: Cape Misaki, Sado Island, Niigata Prefecture, Japan.

Rarity

Extremely rare

For collectors

## Quality criteria As an extremely rare mineral, every specimen is valuable to specialized collectors. Samples with well-formed, sharp crystals of intense color, forming rich aggregates on a small rock matrix, are most highly prized. The absence of damage is crucial. ## Popular localities The only specimens available on the collector's market come from the type locality in Japan. They are extremely difficult to acquire.

Care and storage

## Cleaning Dry cleaning is recommended, using a soft brush or compressed air from a safe distance. Avoid contact with water and any chemical agents. ## What to avoid The mineral is potentially sensitive to moisture and acids. It should not be washed in water, especially in ultrasonic cleaners. It should be protected from sudden temperature changes and direct sunlight. ## Storage Misakiite specimens should be stored in a dry and stable environment. It is recommended to keep them in sealed containers (e.g., membrane boxes or display cases with a desiccant) to minimize the risk of degradation.

External references

Sources

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