Browneite

Chemical formula: Mn<sup>2+</sup>S<sup>2-</sup>

Browneite is an extremely rare manganese sulfide, found exclusively in the Zakłodzie meteorite.

## Characteristics Browneite is a manganese sulfide, known only from microscopic grains. In reflected light, it has a metallic luster and a gray color with a delicate, greenish tint. It occurs as anhedral (irregular) grains, usually not exceeding 15 micrometers in size. It is the mineral analogue of pure manganese sulfide (MnS). ## Physical Properties Due to the microscopic size of the grains, most physical properties have not been directly measured. It is an opaque mineral with a metallic luster. Its density, calculated based on chemical composition and crystal structure, is 4.05 g/cm³. Hardness and streak have not been determined. ## Colors and Varieties No different colors or varieties have been observed. The mineral is colorimetrically uniform. ## History and Name Browneite was officially recognized as a new mineral by the International Mineralogical Association (IMA) in 2010 (IMA2010-041). Its name honors Patrick J. Browne, a New Zealand geologist, for his contributions to geothermal and volcanic research. The mineral was discovered and described in the Zakłodzie meteorite, which fell in Poland. ## Uses Browneite has no industrial or commercial applications due to its extreme rarity and microscopic size. It is of scientific importance only.

Properties

Luster
Metallic
Density
4.05
Transparency
Opaque
Crystal system
Cubic

Diagnostic features

## Identification Identification of browneite is possible only with advanced laboratory techniques, such as electron microprobe (EDS/WDS) for chemical composition analysis. Visual recognition at the macroscopic scale is impossible. ## Distinguishing from Similar Minerals Within the Zakłodzie meteorite, it occurs together with other sulfides, such as troilite (FeS) and keilite ((Fe,Mn)S). Differentiation requires micro-scale chemical analysis. It is a chemically purer form of MnS than the historically described, often iron-containing alabandite. ## Crystal Forms It occurs exclusively as anhedral (irregular), rounded grains. No well-formed crystals have been observed.

Geological environment

## Genesis Browneite formed under strongly reducing conditions within the parent body of the asteroid from which the Zakłodzie meteorite (an enstatite achondrite) originated. It crystallized from a sulfide-rich melt at high temperatures. ## Mineral Associations It co-occurs with minerals typical of enstatite meteorites, such as enstatite, plagioclase, silica, kamacite, troilite, keilite, and niningerite. ## Localities The only confirmed locality in the world is the Zakłodzie meteorite, found in 1998 near the village of Zakłodzie, Lublin Voivodeship, Poland.

Rarity

Extremely rare

For collectors

## Quality Criteria The collector's value does not apply to browneite itself, but to the fragment of the Zakłodzie meteorite in which it was identified. Specimens are valuable due to their extraterrestrial origin and status as the "type locality" for several minerals, including browneite. The mineral itself is invisible to the naked eye. ## Popular Localities The only locality is the Zakłodzie meteorite. Fragments of this meteorite are found in institutional and private collections worldwide.

Care and storage

## Cleaning Specimens (meteorite fragments) containing browneite should not be wet cleaned. Dust can only be removed with a soft brush or compressed air. ## What to Avoid Avoid contact with water, moisture, and chemicals, as sulfides can oxidize and decompose. Protect it from sudden changes in temperature and humidity. ## Storage Meteorite fragments with browneite should be stored in a dry, stable environment, preferably in a sealed container (e.g., a membrane box) with a desiccant.

Sources

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