Pansnerite

Chemical formula: K₃Na₃Fe³⁺₆(As⁵⁺O₄)₈

Pansnerite is a very rare potassium, sodium, and iron arsenate, forming microscopic, hexagonal crystals of a reddish-brown color.

## Characteristics Pansnerite is an extremely rare mineral from the arsenate group, with a complex chemical composition including potassium, sodium, and iron. It occurs as very small, tabular or platy crystals with a hexagonal outline, rarely exceeding 100 micrometers in size. It typically forms thin coatings and crusts on rock surfaces. Its crystals are too small to be observed with the naked eye, and their identification requires advanced analytical techniques. ## Physical Properties Due to the microscopic size of its crystals, most of pansnerite's physical properties have not been fully determined. The crystals exhibit a luster described as submetallic to vitreous. It is a brittle mineral. Hardness and density have not been measured due to the lack of sufficiently large material for testing. ## Colors and Varieties Pansnerite has a characteristic reddish-brown to brownish-black color. No varieties have been distinguished. ## History and Name The mineral was discovered in the dumps of the former uranium mine in the ore-bearing region of Jáchymov, Czech Republic. It was approved by the International Mineralogical Association (IMA) in 2014 (IMA2014-063). Its name honors Robert J. Pansner, an American mineral collector who specialized in minerals from Jáchymov and provided the sample on which the discovery was made. ## Uses Pansnerite has no industrial application. Due to its extreme rarity and microscopic size, it is of interest only to specialized micromount mineral collectors and scientific institutions.

Properties

Mohs hardness
3
Color
Light green, pale greenish, yellowish–greenish or yellowish
Luster
Submetallic to vitreous
Streak
Light brown
Density
3.596
Cleavage
perfect {010}
Fracture
Uneven
Transparency
Transparent,Translucent
Crystal system
Orthorhombic

Diagnostic features

## Identification Identification of pansnerite is impossible without advanced laboratory equipment. Preliminary recognition based on reddish-brown, microscopic hexagonal crystals in paragenesis with other rare arsenates from Jáchymov may be an indication, but confirmation requires chemical composition analysis (EDS) and X-ray diffraction (XRD). ## Distinguishing from Similar Minerals It can be confused with other rare, secondary iron arsenates of similar color, such as pharmacosiderite, symplesite, or scorodite, which may co-occur in the same environment. Differentiation is based on crystal shape analysis (hexagonal tablets in the case of pansnerite) and precise chemical analysis. ## Crystal Forms Pansnerite forms thin, tabular crystals with a hexagonal outline, often grouped into rosette aggregates or forming thin crusts and coatings.

Geological environment

## Genesis Pansnerite is a secondary mineral that forms in the oxidation (weathering) zone of ore deposits rich in arsenic. It forms as a result of reactions of arsenic-rich solutions with primary iron-bearing minerals, in the presence of sodium and potassium. Its occurrence is associated with hydrothermal processes and subsequent weathering. ## Mineral Associations In its type locality (Jáchymov), pansnerite co-occurs with other rare arsenates, such as ekaterinite, metanováčekite, arsenuranospathite, štěpite, and undimite. These minerals form complex parageneses on host rocks. ## Localities The only confirmed locality of pansnerite in the world is its type locality - the Jáchymov region (formerly Sankt Joachimsthal) in the Ore Mountains (Krušné Hory), Czech Republic. The mineral was found on material from historical mines, particularly from the Geschieber vein.

Rarity

Extremely rare

For collectors

## Quality Criteria For micromount collectors, the most valuable specimens are those showing well-formed, individual crystals or aesthetic groups of crystals with a distinct hexagonal outline and an intense, reddish-brown color. Contrast with the rock matrix and the presence of other rare associated minerals are also important. ## Popular Localities The only source of pansnerite specimens is its type locality in Jáchymov, Czech Republic. All samples available on the collector's market originate from this single location.

Care and storage

## Cleaning Specimens of pansnerite should generally not be cleaned. Any attempts at mechanical or chemical cleaning can irreversibly destroy the microscopic crystals. If absolutely necessary, compressed air (from a safe distance) can be used to remove loose dust. ## What to Avoid Avoid contact with water, chemicals, ultrasound, and all forms of mechanical cleaning (brushes, cloths). The mineral is brittle and sensitive to chemical changes. ## Storage Specimens should be stored exclusively in specialized micromount boxes to protect them from dust, mechanical damage, and moisture. Store in stable room conditions, away from direct sunlight and heat sources.

External references

Sources

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