Suenoite
Chemical formula: ◻Mn²⁺₂Mg₅Si₈O₂₂(OH)₂
Suenoite is a rare amphibole group mineral, a magnesium-manganese analogue of cummingtonite, forming fibrous or prismatic crystals.
Properties
- Mohs hardness
- 5.5-6
- Color
- colorless
- Luster
- Vitreous, silky
- Streak
- white
- Density
- 3.283
- Cleavage
- {210}
- Fracture
- Irregular/Uneven
- Transparency
- Transparent
- Crystal system
- Orthorhombic
Diagnostic features
## Identification Suenoite is most easily recognized by its fibrous or elongated, prismatic form and subtle, brownish color. The silky luster on the surface of aggregates is also characteristic. It occurs in specific manganese-rich metamorphic rock environments. ## Distinguishing from Similar Minerals It can be confused with other amphiboles from the cummingtonite-grunerite series. It differs from cummingtonite by its higher manganese content, and from grunerite by its higher magnesium content. Visually, it is almost impossible to distinguish from tirodite, another manganese amphibole. Definitive identification requires advanced chemical analyses (EDS/WDS) or X-ray diffraction (XRD). ## Crystal Forms Suenoite crystals are prismatic, often acicular or fibrous. They typically form radial aggregates, tangled masses (felted), or occur as irregularly shaped grains embedded in the rock.
Geological environment
## Genesis Suenoite is a mineral formed under regional metamorphic conditions, in rocks rich in manganese and magnesium, and poor in calcium. It forms in zones from greenschist to amphibolite facies. ## Mineral Associations It most commonly co-occurs with other metamorphic minerals such as rhodonite, spessartine (manganese garnet), galaxite, pyroxmangite, dannemorite, as well as quartz and other amphiboles. ## Localities The most important and classic occurrences of this mineral are in Japan, especially in the Suwa (type locality) and Kaso mines in Tochigi Prefecture. It is also known from several other locations worldwide, including Bald Knob in North Carolina (USA) and the Tirodi mine in Madhya Pradesh, India.
Rarity
Very rare
For collectors
## Quality Criteria The most prized specimens by collectors are those with well-formed, macroscopically visible prismatic crystals, which are very rare. Rich, radial fibrous aggregates that stand out clearly from the host rock (matrix) are also attractive. Purity and lack of damage to delicate fibers significantly increase the value of a specimen. ## Popular Localities Specimens from Japanese localities, which provided the type material, are considered the best. Specimens from Bald Knob in the USA are also sought after by specialists and systematic mineral collectors.
Care and storage
## Cleaning Suenoite specimens should be cleaned very carefully, preferably using a soft brush to remove dust. Fibrous aggregates are fragile and prone to disintegration. If washing is necessary, use distilled water and avoid a strong stream. After cleaning, the specimen should be left to air dry completely at room temperature. ## What to Avoid Avoid contact with acids and other chemicals that may react with the mineral. Do not heat it or expose it to sudden temperature changes. Cleaning in ultrasonic cleaners is prohibited, as vibrations will destroy the delicate, fibrous structures. ## Storage Suenoite specimens, especially those with a fibrous structure, should be stored in closed display boxes to protect them from dust and mechanical damage. Avoid placing heavier minerals on top of them. It is not sensitive to sunlight.