Maneckiite

Chemical formula: (Na&#9744;)Ca<sub>2</sub>Fe<sup>2+</sup><sub>2</sub>(Fe<sup>3+</sup>Mg)Mn<sup>2+</sup><sub>2</sub>(PO<sub>4</sub>)<sub>6</sub>·2H<sub>2</sub>O

An extremely rare mineral from the phosphate group, forming dark, platy crystals, known exclusively from one locality in the world – a pegmatite in Lower Silesia.

## Characteristics Maneckiite is a complex, hydrated phosphate of sodium, calcium, iron, magnesium, and manganese. It occurs as very small, opaque crystals up to 0.02 mm thick and up to 0.3 mm long. It forms thin, platy or bladed shapes, often grouped into rosette-like or nearly parallel aggregates. Its color is dark, ranging from greenish-brown to almost black. ## Physical Properties The mineral is characterized by a vitreous luster, transitioning to submetallic on some surfaces. It is opaque. Due to the small size of the crystals, its hardness and density have not been precisely measured. The density calculated based on chemical composition and unit cell parameters is approximately 3.65 g/cm³. ## Colors and Varieties The observed color of maneckiite is uniform, in shades from dark green and brown to black. No color or commercial varieties have been distinguished. ## History and Name The mineral was officially recognized by the International Mineralogical Association (IMA) in 2008. Its name honors Professor Andrzej Manecki (born 1933), an outstanding Polish mineralogist, petrologist, and geochemist, associated with the AGH University of Science and Technology in Krakow, in recognition of his contribution to Earth sciences. ## Applications Due to its extreme rarity and occurrence as microscopic crystals, maneckiite has no practical applications. It is solely an object of scientific and collecting interest for specialized collectors of rare minerals (so-called microminerals).

Properties

Luster
Vitreous to submetallic
Streak
Greenish brown
Density
3.65
Transparency
Opaque
Crystal system
Triclinic

Diagnostic features

## Identification Amateur identification of maneckiite is practically impossible. A key diagnostic feature is its origin from the only known locality in the world. Visually, it is simply a "small, black mineral." Definitive identification requires advanced analytical techniques, such as X-ray microanalysis (EDS/WDS) to determine chemical composition and X-ray diffraction (XRD) to confirm crystal structure. ## Distinguishing from Similar Minerals It can be confused with other dark phosphate or oxide minerals found in pegmatites, such as rockbridgeite, strengite, vivianite, or members of the wolframite group. Distinguishing it from these is only possible through laboratory analysis. ## Crystal Forms Crystals are thin, platy, or bladed. They usually form small, radial aggregates resembling rosettes or packets of nearly parallel lamellae.

Geological environment

## Genesis Maneckiite is a hydrothermal mineral, associated with processes occurring in the late stage of granite pegmatite crystallization. It forms in phosphorus-rich zones, likely as a result of metasomatic alteration of earlier phosphates. ## Mineral Associations It co-occurs with other, often rare, phosphate minerals. Its most common associations include goyazite, variscite, strengite, vivianite, rockbridgeite, phosphosiderite, as well as pegmatite-forming minerals such as quartz and microcline. ## Localities The only confirmed locality of maneckiite in the world is the Gęsiniec pegmatite, located in the Strzegom-Sobótka granite massif in Lower Silesia, Poland. This is its type locality.

Rarity

Extremely rare

For collectors

## Quality Criteria The quality of a maneckiite specimen is assessed primarily from a scientific and micro-collecting perspective. Samples with well-formed, even if tiny, crystalline aggregates are most highly valued. A rich association with other rare phosphates is also important, as it enhances the contextual value of the specimen. Size and aesthetics in the classical sense are of secondary importance. ## Popular Localities The only source of specimens is the Gęsiniec mine near Strzegom, Poland. Material from this locality is extremely difficult to obtain and appears in the collecting market sporadically, mainly through exchange among specialists.

Care and storage

## Cleaning Maneckiite specimens are extremely delicate and small. Cleaning should be limited to very carefully removing dust with a soft brush or a photographic air blower. Do not use water, detergents, or any chemical agents. ## What to Avoid Ultrasonic cleaners should be absolutely avoided, as they would destroy the specimen. The mineral should be protected from contact with chemicals, moisture, sudden temperature changes, and direct sunlight, which could cause its degradation. ## Storage The safest storage method is to place the specimen in a closed, padded "micromount" box, away from vibrations and dust. Stable environmental conditions are crucial for preserving the integrity of this rare mineral.

External references

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