Jagoite

Chemical formula: Pb<sup>2+</sup><sub>9</sub>Fe<sup>3+</sup><sub>2</sub>[Si<sub>2</sub>(Si,Fe<sup>3+</sup>)<sub>3</sub>][Pb<sup>2+</sup><sub>2</sub>Si<sub>8</sub>(Si,Fe<sup>3+</sup>)<sub>2</sub>]O<sub>41</sub>Cl<sub>3</sub>

Jagoite is a very rare lead iron silicate, forming small, hexagonal flakes with a characteristic golden-yellow color.

## Characteristics Jagoite is an extremely rare, complex lead iron silicate, occurring as very small, thin, hexagonal plates or flakes. Its typical specimens have an intense, golden-yellow or yellowish-brown color and a vitreous luster. Due to its rarity and small crystal sizes, it is a mineral known mainly in scientific circles and among specialized collectors. ## Physical Properties Jagoite crystals are very small and brittle. The mineral is characterized by a hardness of about 3 on the Mohs scale and a relatively high density of about 6.08 g/cm³, which is typical for lead-rich minerals. It has a vitreous luster, and its flakes can be transparent to translucent. ## Colors and Varieties Jagoite occurs in a characteristic, uniform golden-yellow color, sometimes transitioning to yellowish-brown. No color varieties or commercial varieties are known. ## History and Name The mineral was first described in 1957 by Blix, Gabrielson, and Wickman. Its name commemorates John B. Jago (1893–1970), an American chemist and mineral collector from San Francisco, California, who first drew attention to this mineral in material collected in Långban. ## Uses Jagoite has no industrial application. Its significance is purely scientific and collectible.

Properties

Mohs hardness
3
Luster
Vitreous
Streak
Pale yellow
Density
6.08
Cleavage
Perfect on {0001}
Fracture
Uneven
Transparency
Transparent to translucent
Crystal system
Hexagonal

Diagnostic features

## Identification Jagoite is identified based on its unique combination of features: golden-yellow color, hexagonal habit of thin flakes, high density, and co-occurrence with other rare minerals from Långban. Due to the size of the crystals, identification usually requires microscopic magnification. ## Distinguishing from Similar Minerals It can be confused with other small, yellow secondary lead minerals. Distinguishing it from mimetite or pyromorphite requires analysis of crystal form (hexagonal flakes in the case of jagoite) and often advanced research methods, such as XRD. ## Crystal Forms It forms very small, thin, hexagonal flakes and plates, rarely exceeding 1 mm in diameter. It occurs as scattered scales on the surface of the host rock.

Geological environment

## Genesis Jagoite is a mineral of metamorphic origin. It forms in thermally altered, metamorphosed iron and manganese ore deposits. Its occurrence is limited to very specific geochemical conditions. ## Mineral Associations This mineral co-occurs with other rare minerals typical of the Långban locality, such as hematite, magnetite, quartz, barite, hausmannite, andradite, macedonite, phlogopite, and hedyphane. ## Localities The only confirmed and classic locality for jagoite in the world is the iron-manganese deposits in Långban, in the Filipstad region (Värmland), Sweden. This is its type locality.

Rarity

Very rare

For collectors

## Quality Criteria The most highly prized jagoite specimens are those that possess numerous, well-formed, and clearly visible crystals of intense, golden-yellow color, contrasting with the dark host rock. Due to the microscopic nature of the mineral, the richness and aesthetics of the aggregate, rather than the size of individual crystals, are key. ## Popular Localities The only source of collectible specimens is the historic mine in Långban, Sweden. Material from this locality is extremely sought after and rarely available on the market.

Care and storage

## Cleaning Jagoite specimens are extremely delicate and small. Mechanical cleaning is not recommended. If necessary, compressed air can be used to remove dust. Avoid contact with water and any chemicals. ## What to Avoid Absolutely avoid ultrasonic cleaners, steam cleaners, acids, solvents, and sudden temperature changes. The mineral is brittle and sensitive to mechanical shocks. ## Storage Specimens should be stored exclusively in stable, sealed "micromount" boxes, protecting them from dust, vibrations, and light. Due to its lead content, hands should be washed after each contact with the mineral.

External references

Sources

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