Manganese

Chemical formula: Mn

Native manganese is a very rare native mineral, occurring as small grains and aggregates with a metallic luster.

## Characteristics Native manganese is a chemical element (Mn) found in nature in its pure form, which is an extremely rare phenomenon. It forms small, irregular grains, flakes, or dendritic aggregates, usually not exceeding a few millimeters in size. Its surface is typically dull, covered with a dark oxide tarnish, but on a fresh fracture, it exhibits a metallic luster and a silvery-white color that quickly darkens upon exposure to air. ## Physical Properties This mineral is brittle and relatively soft. It is characterized by a metallic luster on fresh surfaces. It is opaque and has a density close to the theoretical density of pure manganese. ## Colors and Varieties Freshly fractured manganese is silvery-white to gray. Under the influence of oxygen and moisture, it quickly becomes covered with a dark, almost black layer of oxides, which is its typical characteristic. There are no distinct color varieties or commercial varieties. ## History and Name The name manganese comes from the Latin word "magnes" meaning magnet, which refers to the magnetic properties of its oxides (pyrolusite), which were mistaken for magnetite. As an element, it was isolated in 1774 by Johan Gottlieb Gahn. Its occurrence in native form was confirmed much later and is considered a unique mineralogical phenomenon. ## Applications Due to its extreme rarity, native manganese has no industrial applications. It is solely an object of scientific interest and a valuable acquisition for specialized mineral collectors.

Properties

Mohs hardness: 4
Luster: Metallic
Streak: Black
Density: 7.2-7.44
Cleavage: None
Fracture: Uneven
Transparency: Opaque
Crystal system: Cubic

Diagnostic features

## Identification Identification of native manganese is based on its metallic appearance on a fresh fracture, its rapid tendency to darken (oxidize), and its occurrence in specific geological environments. Its brittleness and relatively low hardness are also helpful. However, final identification requires advanced analytical methods, such as chemical composition analysis (EDS). ## Distinguishing from Similar Minerals It can be confused with other native metallic minerals, such as platinum, iron, or antimony. It differs from platinum by its significantly lower hardness and density, and its tendency to oxidize (platinum is chemically inert). It differs from native iron by the absence of magnetic properties. Visual identification is very difficult and uncertain. ## Crystal Forms Native manganese crystals are extremely rare and microscopic in size. It usually occurs in the form of irregular grains, flakes, scales, and in dendritic or skeletal aggregates.

Geological environment

## Genesis Native manganese forms under strongly reducing conditions, with very low availability of oxygen and sulfur. It is most commonly found in manganese-rich metamorphic rocks that have undergone high-temperature alteration. Its presence has also been noted in some hydrothermal deposits and in manganese nodules on the ocean floor, although in the latter form it is extremely rare. ## Mineral Associations It co-occurs with other manganese minerals, such as rhodochrosite, rhodonite, spessartine, tephroite, as well as with galena, alabandite, and other sulfides in hydrothermal veins. ## Localities The most well-known native manganese localities in the world include the Bald Knob mine in North Carolina (USA), Långban in Sweden, and some localities in Germany (Ilfeld) and Japan. These occurrences are primarily of scientific importance.

Rarity

Very rare

For collectors

## Quality Criteria The collector appeal of native manganese is primarily determined by documented provenance from a classic locality. Specimens with clearly visible, even microscopic, crystalline or dendritic forms are most highly valued. The size of the aggregates is also important, but even millimeter-sized grains are considered valuable. Specimens should be embedded in matrix rock. ## Popular Localities The most sought-after specimens by collectors come from historical localities such as Långban in Sweden and Bald Knob in the USA. Every analytically confirmed native manganese specimen is a valuable acquisition for an advanced systematic collector.

Care and storage

## Cleaning Native manganese specimens should generally not be cleaned. Any intervention, especially with water or chemical agents, can accelerate the oxidation process and destroy the natural surface of the mineral. Dust removal should only be done dry, using a soft brush or compressed air from a safe distance. ## What to Avoid Contact with water, moisture, and all chemicals must be strictly avoided. Manganese is very reactive and quickly oxidizes in a humid environment, leading to its permanent damage. It should also be protected from sudden temperature changes. ## Storage Storage requires special conditions. It is best to place the specimen in a sealed, transparent container (a "perky box") with a desiccant (e.g., silica gel). Exposure should be in a dry room, away from direct sunlight and heat sources.