Oxo-mangani-leakeite

Chemical formula: NaNa₂(Mn³⁺₄Li)Si₈O₂₂O₂

A rare silicate from the amphibole group, characterized by a complex chemical composition with dominant manganese and lithium.

## Characteristics Oxo-mangani-leakeite is a complex inosilicate belonging to the amphibole supergroup. This mineral forms prismatic to fibrous crystals, usually small in size, occurring as aggregates. Its color is typically black, and on thin fragments, it may appear dark reddish-brown when translucent. ## Physical Properties It exhibits a vitreous luster and is opaque, except for very thin edges. The Mohs hardness is approximately 6. The mineral's density is estimated at 3.44 g/cm³. ## History and Name The mineral's name reflects its chemical composition and its relationship to the leakeite structure. It indicates the dominance of manganese (mangani) and the presence of an oxide anion (oxo) at a specific position in the crystal structure. It was formally described and approved by the International Mineralogical Association (IMA) as a new mineral species.

Properties

Mohs hardness
6
Color
red-orange
Luster
Vitreous
Streak
Reddish-brown
Density
3.25
Cleavage
parallel to {110}
Fracture
Uneven
Transparency
Transparent
Crystal system
Monoclinic

Diagnostic features

## Identification Identification of oxo-mangani-leakeite requires advanced analytical techniques, such as infrared spectroscopy (IR), electron microprobe analysis (EMPA), or X-ray diffraction (XRD). Under collector conditions, recognition is practically impossible and relies on a label from a trusted source. ## Distinguishing from Similar Minerals It can be confused with other black amphiboles, such as arfvedsonite, riebeckite, or other minerals from the leakeite group. Differentiation without specialized equipment is impossible and relies on chemical analysis to determine the dominant elements. ## Crystal Forms It forms elongated, prismatic crystals, often with a fibrous habit. It usually occurs as radial aggregates or tangled fibrous masses.

Geological environment

## Genesis This is a metamorphic mineral, found in rocks rich in manganese and alkalis. It forms under conditions of regional metamorphism, likely in the amphibolite facies. ## Mineral Associations At its type locality, it co-occurs with quartz, microcline, albite, aegirine, rhodonite, spessartine, and other minerals from the amphibole group. ## Localities The only confirmed occurrence of this mineral in the world is the Wessels Mine in the Hotazel area, in the Kalahari Manganese Field in the Republic of South Africa.

Rarity

Extremely rare

For collectors

## Quality Criteria Due to its extreme rarity, every specimen is valuable to specialized collectors. The most desirable specimens are those with well-formed, even if microscopic, crystals, clearly visible against the matrix rock. Precise analytical identification confirming the mineral species is crucial.

Care and storage

## Cleaning It is recommended to clean only with compressed air or a very soft brush. Avoid contact with water and chemical agents, as the mineral may be sensitive to their effects. ## What to Avoid Avoid ultrasonic cleaners, sudden temperature changes, and all acids and detergents. The mineral is brittle and should be protected from impacts and scratching. ## Storage Specimens should be stored in stable conditions, in a dry place, away from direct sunlight. It is best to place them in a sealed display box to protect them from dust and mechanical damage.

External references

Sources

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