Strandite

Chemical formula: Pb₂+₃Mn₃+₄Mn₄+₃O₁₅

An extremely rare lead and manganese oxide, known exclusively from the famous Långban deposit in Sweden.

## Characteristics Strandite is a complex lead and manganese oxide in which manganese occurs in two different oxidation states (III and IV). It belongs to a group of extremely rare minerals identified in material from the historic Långban deposit. As a rule, it forms very fine, microscopic crystals or inclusions in other minerals. ## Physical properties As a lead and manganese oxide, strandite is an opaque mineral of dark color. Due to the microscopic size of known crystals, accurate determination of its macroscopic physical properties is difficult. It crystallizes in the hexagonal system. ## Colors and varieties This mineral takes on a black color, characteristic of many complex manganese oxides. It has no distinct varieties. ## History and name Strandite was described based on material originating from the famous Långban mine in Sweden, which is the type locality for several dozen rare mineral species. ## Uses Due to its extreme rarity, this mineral has no practical application. It serves exclusively as an object of mineralogical research and a sought-after specimen in specialized systematic collections.

Properties

Transparency: Opaque
Crystal system: Hexagonal

Diagnostic features

## Identification Macroscopic identification of strandite is impossible. Its unequivocal identification requires advanced analytical methods, including X-ray diffraction (XRD) and micro-area chemical composition analysis (e.g., EDS/WDS). ## Distinguishing from similar minerals Visually, strandite is indistinguishable from many other black, opaque manganese and lead oxides occurring in the Långban deposit, such as plumboferrite, senaite, or melanostibite. ## Crystal habits The mineral crystallizes in the hexagonal system. It usually occurs as microscopic grains and very fine aggregates.

Geological environment

## Genesis Strandite forms under specific geochemical conditions in metamorphosed iron and manganese deposits that have been enriched in lead and other trace elements. ## Mineral associations It co-occurs with other rare minerals typical of skarns and metamorphosed manganese-iron ores at Långban. ## Localities The only confirmed locality of this mineral in the world is the historic Långban mine, located in the Långban ore district (Filipstad Municipality, Värmland County), Sweden.

Rarity

Extremely rare

For collectors

## Quality criteria In the case of strandite, the sole criterion of collector value is the analytically confirmed identity of the specimen. Aesthetic qualities do not apply here due to the microscopic nature of the mineral. ## Popular localities All known specimens come exclusively from the type locality in Långban, Sweden. This deposit is historically closed, which further increases the scientific and collector value of preserved samples.

Care and storage

## Cleaning Specimens containing strandite should be cleaned exclusively using compressed air. Washing in water and using ultrasonic cleaners should be avoided to prevent damage to microscopic crystals. ## What to avoid Contact with any chemicals, especially acids, which can react with lead and manganese oxides, must be strictly avoided. Specimens should be protected from mechanical damage and abrasion. ## Storage Specimens should be stored in airtight micromount boxes, permanently attached to the base, which protects them from dust, moisture, and shocks.

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External references

https://www.mindat.org/min-499368.html