Mangano-mangani-ungarettiite

Chemical formula: NaNa₂(Mn₂+₂Mn₃+₃)Si₈O₂₂O₂

A rare, black sodium amphibole of the richterite group, distinguished by its complex chemical composition with dominant manganese.

## Characteristics Mangano-mangani-ungarettiite is a very rare mineral of the amphibole group, specifically a sodium amphibole of the richterite group. It forms prismatic, elongated crystals, typically not exceeding 1 mm in length. It occurs as fibrous or acicular aggregates. It is black and opaque, with a visible luster on the crystal faces. ## Physical Properties This mineral is characterized by a vitreous luster. Its Mohs hardness is approximately 6, and its density, calculated from the chemical formula, is 3.43 g/cm³. The crystals exhibit perfect cleavage, typical of amphiboles. ## Colors and Varieties The mineral is uniformly black. No color varieties or commercial forms are known. ## History and Name The mineral's name reflects its chemical composition and honors the Italian crystallographer Luciano Ungaretti (1942-2002) from the University of Pavia, for his contributions to amphibole research. The first part of the name, "mangano", refers to the dominance of divalent manganese (Mn²⁺) in a specific crystallographic site, and "mangani" to the presence of trivalent manganese (Mn³⁺). The mineral was approved by the International Mineralogical Association (IMA) in 2003.

Properties

Mohs hardness: 6
Luster: Vitreous
Streak: Grey
Density: 3.43
Cleavage: Perfect on {110}
Fracture: Uneven
Transparency: Opaque
Crystal system: Monoclinic

Diagnostic features

## Identification Identification of this mineral is extremely difficult without advanced analytical methods. Preliminary identification is based on its black color, prismatic habit, occurrence in a characteristic geological environment (veins in manganese deposits), and association with other manganese minerals. Final confirmation requires chemical analysis (EDS/WDS) and X-ray diffraction (XRD). ## Differentiation from Similar Minerals It can be confused with other black, prismatic amphiboles, such as arfvedsonite, riebeckite, or other rare manganese amphiboles. Visual differentiation is practically impossible and requires specialized laboratory investigations. ## Crystal Forms It forms elongated, prismatic crystals with a rhombic cross-section, often as acicular or fibrous aggregates. Crystals are typically very small, up to 1 mm in length.

Geological environment

## Genesis This is a mineral of metamorphic origin. It forms as a result of hydrothermal processes or low-grade metamorphism within manganese-rich, alkalized sedimentary rocks. It occurs in veins cutting through manganese ore deposits. ## Mineral Associations This mineral co-occurs with other manganese minerals and silicates, such as quartz, braunite, piemontite, rhodonite, aegirine, norrishite, and hematite. ## Localities The only confirmed occurrence of this mineral worldwide (type locality) is the Cerchiara mine in Liguria, Italy. This is a small manganese mine known for the occurrence of many rare minerals.

Rarity

Extremely rare

For collectors

## Quality Criteria As a microscopic mineral, its collector's value is primarily determined by the richness and quality of the crystals on the rock matrix. Specimens with well-formed, lustrous crystals forming dense aggregates are most desirable. Contrast with a light matrix (e.g., quartz) also enhances the specimen's attractiveness. ## Popular Localities The Cerchiara mine in Italy is the sole source of specimens, making them extremely sought after by collectors specializing in rare minerals (so-called "micromounts") and minerals from specific localities.

Care and storage

## Cleaning Due to the fibrous or acicular nature of the aggregates, mechanical cleaning is not recommended. Compressed air can be used to remove dust. Any wet cleaning should be performed with utmost caution, using only distilled water. ## What to Avoid Avoid contact with acids and other chemicals. Brittle and tiny crystals are very susceptible to mechanical damage, so avoid vibrations, impacts, and friction. ## Storage Specimens should be stored in stable, sealed containers (e.g., micromount type) to protect them from dust and mechanical damage. Due to the small size of the crystals, magnification is required for display.

Sources

IMA Mineral List (CNMNC)