Chladniite

Chemical formula: Na₃CaMg₁₁(PO₄)₉

Chladniite is an extremely rare sodium, calcium, and magnesium phosphate, found exclusively in meteorites, forming tiny, colorless grains.

## Characteristics Chladniite is a mineral from the phosphate group, occurring as very small, anhedral (not exhibiting its own crystal form) grains. It is typically colorless and transparent, with a vitreous luster. Due to its extreme rarity and microscopic crystal size, its visual characteristics are difficult to assess without specialized equipment. It is observed as inclusions in other meteoritic minerals. ## Physical Properties The mineral is characterized by a Mohs hardness of 5. It has a vitreous luster and is transparent. The density calculated based on the formula and unit cell parameters is approximately 3.16 g/cm³. No cleavage or fluorescence has been observed. ## Colors and Varieties Chladniite is typically colorless. No colored or commercial varieties are known. ## History and Name The mineral is named in honor of Ernst Florens Friedrich Chladni (1756-1827), a German physicist and astronomer, a pioneer in meteorite research, who was the first to propose their extraterrestrial origin. The mineral was officially recognized by the International Mineralogical Association (IMA) in 1993. The type locality is the Carlton iron meteorite (IIICD) found in Hamilton County, Texas, USA. ## Uses Chladniite has no industrial applications. Its significance is purely scientific and collectible, as a component of rare types of meteorites.

Properties

Mohs hardness: 5
Luster: Vitreous
Streak: White
Density: 3.16
Cleavage: None
Fracture: Uneven
Transparency: Transparent
Crystal system: Trigonal

Diagnostic features

## Identification Identification of chladniite is impossible without advanced laboratory techniques, such as X-ray microanalysis (EDS/WDS) or X-ray diffraction (XRD). In meteorites, it occurs as microscopic, colorless grains that are visually indistinguishable from many other minerals. ## Distinguishing from Similar Minerals It can be confused with other phosphates found in meteorites, such as johnsomervilleite, farringtonite, or merrillite. Definitive distinction requires chemical composition analysis, especially the proportions of sodium, calcium, and magnesium. ## Crystal Forms Chladniite forms only very fine, anhedral grains of irregular shape, usually not exceeding 100 micrometers in size. Well-formed crystal faces are not observed.

Geological environment

## Genesis Chladniite is a mineral of extraterrestrial origin. It forms under specific conditions during the formation or metamorphism of certain types of meteorites, particularly in IIICD iron meteorites and in pallasites (e.g., Eagle Station). It forms in the presence of other phosphates within a metallic matrix (kamacite, taenite). ## Mineral Associations It co-occurs with other meteoritic minerals such as kamacite, taenite, schreibersite, graphite, and also with other phosphates, e.g., brianite, panethite, and buchwaldite. ## Localities Its occurrence has been confirmed in several meteorites worldwide. The main ones include the Carlton iron meteorite (Texas, USA), which is the type locality, and pallasites from the Eagle Station group.

Rarity

Extremely rare

For collectors

## Quality Criteria Since chladniite occurs as microscopic inclusions, it is not evaluated based on typical collector criteria such as color or form. The value of a specimen is determined by the value of the meteorite itself in which the mineral has been identified. For scientific institutions and specialized collectors, the confirmed presence of this rare mineral alone is valuable. ## Popular Localities The most well-known source of specimens with chladniite is the Carlton meteorite (Texas, USA). Any meteorite specimen in which this mineral has been identified is a valuable scientific and collectible acquisition.

Care and storage

## Cleaning Specimens containing chladniite (typically meteorite fragments) should not be wet-cleaned. Dust should only be removed with a soft brush or compressed air from a safe distance. ## What to Avoid Avoid contact with water, chemicals, acids, and cleaning agents, which can damage both the chladniite itself and the surrounding minerals in the meteorite. Iron meteorites are susceptible to rusting, so protection from moisture is crucial. ## Storage Meteorite fragments with chladniite should be stored in a dry environment, preferably in a sealed container (e.g., membrane or plastic) with a desiccant (e.g., silica gel). Avoid rapid temperature changes.

Sources

IMA Mineral List (CNMNC)