Magnesiohögbomite-2N4S

Chemical formula: (Mg₈.₄₃Fe₂+₁.₅₇)Al₂₂Ti₄+₂O₄₆(OH)₂

Magnesiohögbomite-2N4S is a very rare, black mineral from the högbomite group, found in magnesium-rich metamorphic rocks.

## Characteristics Magnesiohögbomite-2N4S is a mineral belonging to the högbomite supergroup. It typically forms small, tabular or prismatic crystals with a hexagonal outline, reaching up to 1 mm in size. It occurs as inclusions in other minerals, mainly corundum. It is opaque and black in color. ## Physical Properties This mineral is characterized by a hardness of 7.5-8 on the Mohs scale, making it relatively hard. It has a metallic to submetallic luster. Its density is approximately 3.81 g/cm³. ## Colors and Varieties The dominant and only recorded color of magnesiohögbomite-2N4S is black. No color varieties or commercial forms are distinguished. ## History and Name The name "magnesiohögbomite" refers to the dominant magnesium (Mg) in its chemical composition and its association with the högbomite group. The "-2N4S" suffix specifies its polytype, i.e., its specific crystal structure. The mineral was formally described by T. Armbruster and colleagues in 2002 after examining material from Tanzania. ## Applications Due to its extreme rarity and microscopic size, magnesiohögbomite-2N4S has no industrial applications. It is solely an object of scientific and collecting interest for specialized collectors of rare minerals.

Properties

Mohs hardness: 7.5-8
Luster: Metallic
Streak: Black
Density: 3.81
Cleavage: None
Fracture: Uneven
Transparency: Opaque
Crystal system: Hexagonal

Diagnostic features

## Identification Identification of magnesiohögbomite-2N4S is extremely difficult and practically impossible without advanced analytical methods, such as X-ray microanalysis (EDS/WDS) and X-ray diffraction (XRD). In collections, it is identified based on the label and confirmed analysis from the provenance. Visually, it is simply a black, microscopic inclusion. ## Distinguishing from Similar Minerals It can be confused with other black minerals included in corundum, such as hercynite, magnetite, ilmenite, or other minerals from the högbomite group. Differentiation requires specialized laboratory equipment. ## Crystal Forms It forms small, hexagonal, tabular crystals, often with a prismatic habit. It usually occurs as single, isolated crystals embedded in the host mineral.

Geological environment

## Genesis It forms under conditions of high-grade metamorphism, in aluminum- and magnesium-rich rocks. In its type locality (Mautia Hill, Tanzania), it occurs in a rock called rodingite, which formed as a result of metasomatism associated with the serpentinization of ultramafic intrusions. ## Mineral Associations It co-occurs with minerals such as corundum (often as an inclusion), anorthite, clinochlore, dolomite, spinel, geikielite, and titanite. ## Localities The most important and type locality is Mautia Hill in the Kongwa region, Dodoma, Tanzania. This is the only confirmed and well-documented locality for this mineral worldwide.

Rarity

Extremely rare

For collectors

## Quality Criteria For collectors, the most important criterion is the confirmation of the specimen's authenticity through chemical analysis. The size and quality of the crystals are of secondary importance, as they are always microscopic. The most desirable specimens are those where the magnesiohögbomite crystal is clearly visible against a contrasting host mineral, such as light-colored corundum. ## Popular Localities The only source of collector specimens is the type locality in Tanzania (Mautia Hill).

Care and storage

## Cleaning Specimens, typically as inclusions in corundum, can be gently cleaned with compressed air to remove dust. Mechanical or chemical cleaning is not recommended due to the risk of damaging the microscopic crystals. ## What to Avoid Avoid contact with acids and strong chemicals. Despite its high hardness, specimens are brittle and should be protected from impacts and scratching. ## Storage Store in stable conditions, away from dust and moisture, preferably in a sealed "micromount" box. Exposure to strong light is not harmful, but also not necessary.

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