D'ansite-(Mn)

Chemical formula: Na₂₁Mn₂+(S₆+O₄)₁₀Cl₃

D'ansite-(Mn) is a rare sodium and manganese sulfate, forming small, vitreous crystals with a regular structure.

## Characteristics D'ansite-(Mn) is a complex sulfate of sodium, manganese, and chlorine. This mineral most often forms small, isometric crystals in the shape of cubes or octahedra, reaching up to 1 mm in size. It occurs as single crystals or granular aggregates. It is a transparent mineral with a vitreous luster. ## Physical Properties It is characterized by a hardness of approximately 3 on the Mohs scale. Its density is about 2.65 g/cm³. It does not exhibit cleavage, and its fracture is conchoidal. It is brittle. ## Colors and Varieties It is usually colorless, rarely taking on a pale yellow hue. No color varieties or commercial varieties are known. ## History and Name The mineral's name refers to its chemical composition – it is the manganese (Mn) analog of d'ansite. It was approved as a new mineral by the International Mineralogical Association (IMA) in 1983. It was described by P.J. Dunn, D.R. Peacor, P.B. Leavens, and R.A. Ramik based on material from a mine in New Jersey, USA.

Properties

Mohs hardness: 3
Luster: Vitreous
Streak: White
Density: 2.65
Cleavage: None
Fracture: Conchoidal
Transparency: Transparent
Crystal system: Cubic

Diagnostic features

## Identification A key diagnostic feature is its regular, isometric crystal form (cubes, octahedra) and its occurrence in a specific geological environment – salt deposits. It reacts with water, which is an important clue. However, identification most often requires advanced analytical methods, such as chemical composition analysis (EDS) or X-ray diffraction (XRD). ## Distinguishing from Similar Minerals It can be confused with other colorless minerals from salt deposits, such as halite or sylvine. It is distinguished from them by its lack of cleavage and different crystal form. Unlike halite, it does not have a salty taste. ## Crystal Forms It forms well-developed, isometric crystals, mainly cubes and octahedra, often in combinations of these forms. It occurs as single crystals or in granular aggregates.

Geological environment

## Genesis It is an evaporite mineral. It forms in marine salt deposits that have undergone metamorphism. It crystallizes under conditions of high salinity and specific chemical composition of brines. ## Mineral Associations It co-occurs with other evaporite minerals such as anhydrite, hematite, franklinite, polyhalite, and also with d'ansite itself. ## Localities The most important and type locality for this mineral is the Sterling Mine in Sterling Hill, Ogdensburg, Sussex County, New Jersey, USA. This is the only confirmed and well-documented locality worldwide.

Rarity

Very rare

For collectors

## Quality Criteria The most prized specimens are those with well-formed, sharp, and transparent crystals, set on a contrasting rock matrix. Due to the small size of the crystals, specimens visible to the naked eye are rare, and most material consists of microminerals. Crystal size is a key factor influencing value. ## Popular Localities The only source of collector specimens is the historic type locality – the Sterling Mine in New Jersey, USA. Material from this location is highly sought after by collectors specializing in systematic minerals and microminerals.

Care and storage

## Cleaning Specimens should only be cleaned with compressed air to remove dust. Due to its water solubility, contact with water is absolutely inadvisable. ## What to Avoid Avoid contact with water, water vapor, and any chemicals that could damage or dissolve it. The mineral is sensitive to moisture and should therefore be protected from high humidity. ## Storage It is recommended to store specimens in sealed, dry containers (e.g., "perky boxes") or in specialized display cases with humidity control. Exposure to open air, especially in humid climates, leads to its slow decomposition.

Sources

IMA Mineral List (CNMNC)