Nežilovite

Chemical formula: Pb₂+[Mn₄+₂Fe₃+₇AlZn₂+₂]O₁₉

Nežilovite is a rare lead, zinc, iron, and manganese oxide, forming small, hexagonal, tabular crystals with a metallic luster.

## Characteristics Nežilovite is a complex oxide from the magnetoplumbite group, occurring as small, hexagonal crystals with a tabular habit. It typically forms grains embedded in rock or small aggregates. Its crystals rarely exceed 1 mm in size. It is an opaque mineral, black in color with a metallic luster. ## Physical Properties Nežilovite is characterized by high hardness, approximately 6 on the Mohs scale, and significant density, reaching 5.85 g/cm³. It has a black streak and metallic luster. It is a brittle mineral with an uneven fracture. It does not exhibit cleavage. ## Colors and Varieties This mineral is uniform in color and occurs exclusively in black. No color or commercial varieties have been distinguished. ## History and Name Nežilovite was discovered and described in 1996. Its name comes from its discovery locality – the Nežilovo deposit in North Macedonia. It was approved by the International Mineralogical Association (IMA) under number IMA1994-041. ## Uses Due to its rarity and small crystal size, nežilovite has no industrial applications. It is solely an object of interest for collectors specializing in rare or systematic minerals.

Properties

Mohs hardness: 6
Luster: Metallic
Streak: Black
Density: 5.85
Cleavage: None
Fracture: Uneven
Transparency: Opaque
Crystal system: Hexagonal

Diagnostic features

## Identification Nežilovite can be identified by its black color, strong metallic luster, and characteristic small, hexagonal, and tabular crystals. Its high hardness and density are also helpful in identification. It occurs in a specific geological environment – within metamorphosed dolomites. ## Distinguishing from Similar Minerals It can be confused with other black, metallic minerals such as magnetite, hematite, or franklinite. It differs from magnetite by the absence of strong magnetic properties and its hexagonal crystal form (magnetite crystallizes in the isometric system). It differs from hematite by its crystal habit and harder streak. Identification often requires advanced research methods, such as chemical composition analysis (EDS). ## Crystal Forms It forms very small, sharp-edged, tabular crystals with a hexagonal outline. They occur as single crystals embedded in rock or in small aggregates.

Geological environment

## Genesis Nežilovite forms under conditions of regional metamorphism, in carbonate rocks (dolomites) rich in manganese and iron. It is a product of transformations occurring at high temperatures and pressures. ## Mineral Associations This mineral co-occurs with minerals such as franklinite, magnetite, gahnospinel, corundum, rutile, braunite, hematite, and diaspore. ## Localities The most important and type locality (locus typicus) is the Mn-Fe-Zn ore deposit in Nežilovo, in the Pelagonian Massif, North Macedonia. This is the only confirmed and thoroughly described locality of this mineral in the world.

Rarity

Very rare

For collectors

## Quality Criteria The collector's appeal of nežilovite specimens primarily depends on the size and development of the crystals. Specimens with clearly visible, sharp-edged, hexagonal crystals contrasting with a lighter host rock are most valued. Due to the microscopic size of the crystals, specimens suitable for viewing under magnification are standard. ## Popular Localities The only source of collector specimens is the type locality in Nežilovo, North Macedonia. Material from this location is extremely limited, and specimens rarely appear on the market.

Care and storage

## Cleaning Due to the small size of the crystals and their occurrence as inclusions within the rock matrix, cleaning is usually neither necessary nor recommended. If needed, dust can be removed with compressed air or a very soft brush. ## What to Avoid Avoid contact with strong acids, which can damage the mineral's surface. Ultrasonic cleaning is not recommended, as vibrations can cause small crystals to dislodge from the matrix. ## Storage Specimens containing nežilovite should be stored in stable conditions, away from dust and moisture. It is best to place them in a sealed display box to protect delicate crystals from mechanical damage.

Sources

IMA Mineral List (CNMNC)