Kenngottite

Chemical formula: Mn²⁺₃Fe³⁺₄(PO₄)₄(OH)₆(H₂O)₂

Kenngottite is a rare, hydrated manganese and iron phosphate, forming brown, platy crystals and aggregates.

## Characteristics Kenngottite is a rare mineral from the phosphate group, chemically classified as a hydrated manganese and iron phosphate. It occurs as small, platy or bladed crystals, often gathered into radial, spherical, or rosette-like aggregates. Its appearance is usually inconspicuous, and specimens rarely exceed a few millimeters in size. ## Physical Properties This mineral is characterized by a hardness of 4-5 on the Mohs scale. Its density is approximately 3.40 g/cm³. Crystals can range from transparent to translucent to opaque. The luster is described as vitreous to resinous. ## Colors and Varieties Kenngottite occurs in various shades of brown. No distinct color varieties or commercial forms have been identified. ## History and Name The mineral is named in honor of Gustav Adolf Kenngott (1818-1897), a Swiss-German mineralogist and professor of mineralogy at ETH Zurich. The mineral was first described in 2003 based on material from a historic tin mine in the Czech Republic. ## Uses Kenngottite has no industrial applications. Its significance is purely scientific and collector-oriented due to its rarity.

Properties

Mohs hardness: 4-5
Luster: Vitreous to resinous
Streak: light brown
Density: 3.40
Cleavage: not directly observed, but probably parallel to {100}
Fracture: Irregular/Uneven
Transparency: Transparent,Translucent,Opaque
Crystal system: Monoclinic

Diagnostic features

## Identification Identification of kenngottite under amateur conditions is practically impossible. It requires advanced analytical methods such as X-ray diffraction (XRD) and chemical analysis (EDS/WDS). Preliminary indications may include its brown color, specific aggregate forms (radial, spherical), and co-occurrence with other rare phosphates in the oxidation zones of ore deposits. ## Distinguishing from Similar Minerals It can be confused with many other secondary iron or manganese phosphates and arsenates, such as cacoxenite, strengite, or rockbridgeite. Definitive differentiation is only possible through laboratory analysis. ## Crystal Forms It forms very small, platy or bladed crystals, most often occurring as radial, spherulitic (spherical), or rosette-like aggregates and crusts on other minerals.

Geological environment

## Genesis Kenngottite is a secondary mineral, forming in the oxidation (weathering) zones of ore deposits, particularly in granitic pegmatites containing primary phosphates such as triplite. It forms as a result of the alteration of these minerals under low-temperature conditions. ## Mineral Associations This mineral co-occurs with other secondary phosphates. In its type locality, it was found in association with rockbridgeite, strengite, beraunite, cacoxenite, triplite, quartz, and goethite. ## Localities The most important and type locality for kenngottite is the historic tin mine Stannum (New Hubner shaft) in Krásno, Czech Republic (Karlovy Vary region). This is the only confirmed and well-documented locality for this mineral worldwide.

Rarity

Very rare

For collectors

## Quality Criteria Due to its extreme rarity and microscopic size, every analytically confirmed kenngottite specimen is valuable to specialized collectors. The most desirable specimens are those with well-formed, radial aggregates, clearly visible under a microscope, embedded in a contrasting rock matrix. The abundance of aggregates on the specimen and the aesthetic composition increase its value. ## Popular Localities The only source of kenngottite specimens is its type locality in Krásno, Czech Republic. Collector material comes from historic dumps and is very difficult to acquire.

Care and storage

## Cleaning Due to their small size and delicate nature, mechanical cleaning of aggregates is not recommended. If necessary, compressed air can be used to remove dust, or the specimen can be very carefully rinsed with distilled water and then thoroughly dried. ## What to Avoid Avoid contact with acids and other chemicals that may damage the mineral. It should not be heated or cleaned in ultrasonic cleaners. As a secondary mineral, it may be sensitive to changes in humidity. ## Storage Kenngottite specimens are best stored under stable conditions, in sealed "micromount" boxes, which protect them from dust, mechanical damage, and sudden changes in humidity.

External references

https://www.mindat.org/min-53374.html