Långbanshyttanite

Chemical formula: Pb₂+₂Mn₂+₂Mg(As₅+O₄)₂(OH)₄·₆H₂O

Långbanshyttanite is a very rare, hydrated lead, manganese, and magnesium arsenate, forming colorless, tabular crystals.

## Characteristics Långbanshyttanite is an extremely rare mineral from the arsenate group, occurring as small, tabular or bladed crystals, usually not exceeding 1 mm in length. The crystals are colorless and transparent, often forming small, rosette-like aggregates or appearing as single flakes on the rock matrix. Due to its chemical composition and rarity, it is a mineral of purely scientific and collecting interest. ## Physical Properties The crystals exhibit perfect cleavage in one direction, which is consistent with their platy structure. The luster is vitreous to pearly on cleavage planes. The hardness of the mineral has not been precisely determined, but it is estimated to be around 2-3 on the Mohs scale, making it very soft and delicate. The density calculated from the formula and unit cell parameters is 4.23 g/cm³. ## History and Name The mineral's name comes from the historical name of the Långban mine in Sweden - Långbanshyttan. It was approved as a new mineral species by the International Mineralogical Association (IMA) in 2010. It was described by Dan Holtstam, Jörgen Langhof, and Andreas Karlsson based on specimens found on the dumps of the Långban mine.

Properties

Mohs hardness: 2-3
Luster: Vitreous, Pearly
Streak: White
Density: 4.23
Cleavage: Perfect on {0001}
Fracture: Micaceous
Transparency: Transparent
Crystal system: Trigonal

Diagnostic features

## Identification Identification is based on a unique set of features: its occurrence as small, colorless, tabular crystals with a pearly luster, extreme rarity, and association with other rare minerals from Långban. Identification requires advanced analytical methods, such as Raman spectroscopy or chemical analysis (EDS). ## Distinguishing from Similar Minerals It can be confused with other colorless, platy secondary minerals, such as gypsum or micas, but it differs from them in its environment of occurrence (specific Långban skarn mineralization) and significantly higher density. Final distinction from similar arsenates (e.g., finnemanite) is only possible through laboratory analysis. ## Crystal Forms It forms thin, tabular crystals with a hexagonal outline, elongated in one direction. Crystals often occur in small, radial or rosette-like aggregates.

Geological environment

## Genesis Långbanshyttanite is a secondary mineral that formed as a result of hydrothermal or metamorphic processes within the iron and manganese ore deposit at Långban. It crystallizes in fissures and small voids in skarns and carbonate rocks, in an environment rich in arsenic, lead, and manganese. ## Mineral Associations This mineral co-occurs with other rare minerals typical of this locality. It has been found in association with finnemanite, hausmannite, magnetite, calcite, barite, and unidentified phyllosilicates from the serpentine group. ## Localities The only confirmed occurrence of långbanshyttanite in the world is its type locality - the Långban mine in the Värmland region of Sweden. All known specimens come from material collected on the old dumps of this historic mine.

Rarity

Extremely rare

For collectors

## Quality Criteria The quality of a specimen primarily depends on the presence of well-formed, even microscopic, crystals with a distinct outline and luster. The most valued are rich aggregates of crystals or single, but well-isolated crystals on a contrasting rock matrix. Due to its extreme rarity, every authentic specimen, even a small one, holds significant value for specialized collectors. ## Popular Localities The only source of specimens is the Långban mine in Sweden, which is one of the most famous mineralogical localities in the world, known for the occurrence of hundreds of unique mineral species.

Care and storage

## Cleaning Specimens should be cleaned only very carefully, using compressed air to remove dust. Any contact with water or chemicals is inadvisable due to the mineral's delicacy and potential solubility. ## What to Avoid Avoid contact with water, acids, cleaning agents, and ultrasonics. The mineral is very soft and brittle, so it should be protected from any impacts and abrasions. It should not be heated or exposed to prolonged moisture. ## Storage Långbanshyttanite requires storage in stable conditions, preferably in a closed, padded display box or cabinet, away from dust, moisture, and direct sunlight. Due to the small size of the crystals, a small "micromount" box is an ideal solution.

Sources

IMA Mineral List (CNMNC)