Clino-suenoite
Chemical formula: ☐{Mn²⁺₂}{Mg₅}Si₈O₂₂(OH)₂
Clino-suenoite is a rare amphibole group mineral, the monoclinic analogue of suenoite, characterized by its occurrence in manganese-rich metamorphic rocks.
Properties
- Mohs hardness
- 5.5-6
- Luster
- Vitreous to silky
- Streak
- Light gray
- Density
- 3.25
- Cleavage
- Perfect on {110}
- Fracture
- Uneven to splintery
- Transparency
- Translucent to opaque
- Crystal system
- Monoclinic
Diagnostic features
## Identification Clino-suenoite in the form of fibrous or radial aggregates with a brownish or greenish color is relatively characteristic. A key diagnostic feature, typical of amphiboles, is perfect cleavage in two directions, intersecting at angles of approximately 56° and 124°. However, these features are only visible on well-formed, larger crystals. ## Distinguishing from Similar Minerals Visual differentiation of clino-suenoite from other amphiboles in the cummingtonite-grunerite series is practically impossible without advanced chemical analyses (e.g., electron microprobe) or X-ray diffraction (XRD). Clino-suenoite is the manganese analogue of magnesium cummingtonite and iron grunerite. It can also be confused with other manganese silicates, such as rhodonite or pyroxmangite, from which it differs in crystal form and cleavage. ## Crystal Forms It forms columnar or acicular crystals, often with a rhombic cross-section. It is most commonly found as fibrous, asbestiform, or radial rosette aggregates.
Geological environment
## Genesis Clino-suenoite is a mineral typical of metamorphosed, manganese-rich sedimentary rocks, such as banded iron formations (BIF) or manganese deposits. It forms under conditions of regional or contact metamorphism at medium to high temperatures and pressures. ## Mineral Associations It often co-occurs with other manganese minerals, such as spessartine (manganese garnet), rhodonite, pyroxmangite, tephroite, as well as with quartz, other amphiboles (e.g., dannemorite), pyroxenes, and manganese oxides. ## Localities Key localities worldwide include: Sueno mine, Tochigi Prefecture, Japan (type locality); Harstigen mine in Pajsberg, Värmland region, Sweden; Broken Hill in New South Wales, Australia; and also some deposits in Brazil and the United States (e.g., North Carolina).
Rarity
Rare
For collectors
## Quality Criteria The most valued specimens by collectors are those with well-formed, sharp crystals, which are very rare. Aesthetic, radial aggregates embedded in a contrasting rock matrix are also highly prized. The value of a specimen is enhanced by its co-occurrence with other rare manganese minerals, such as rhodonite or spessartine. ## Popular Localities Historical localities in Sweden (e.g., Harstigen) and Japan (Sueno mine) are considered classic and provide the best specimens. Specimens from Broken Hill, Australia, are also known for their good quality.
Care and storage
## Cleaning Clino-suenoite specimens should be cleaned very carefully, using a soft brush to remove dust. For heavier soiling, distilled water can be used. Ultrasonic cleaners should be avoided, as they can damage delicate, fibrous aggregates or cause fractures along cleavage planes. ## What to Avoid The mineral is sensitive to strong acids. It should be protected from sudden temperature changes and prolonged exposure to direct sunlight, although no clear effect on color is known. Contact with harder minerals should be avoided to prevent scratching. ## Storage Collector specimens of clino-suenoite are best stored in separate, sealed boxes or display cases to protect them from dust and mechanical damage. Particularly fragile, fibrous aggregates require stable support and minimal contact.