Kahlenbergite

Chemical formula: KAl<sub>11</sub>O<sub>17</sub>

Kahlenbergite is a rare potassium aluminum oxide, forming microscopic, hexagonal plates in meteorites.

## Characteristics Kahlenbergite is an oxide mineral, chemically a potassium aluminum oxide. It occurs as extremely small, hexagonal crystals with a platy habit, typically not exceeding several tens of micrometers in size. It is observed as inclusions in other minerals within meteorites. Due to its microscopic size, its visual characteristics cannot be assessed with the naked eye. ## Physical Properties Due to the extremely small size of the crystals, most physical properties of kahlenbergite have not been precisely measured. Hardness is unknown. Density has been calculated based on the formula and unit cell parameters, and is approximately 3.35 g/cm³. Luster and transparency have not been determined. ## Colors and Varieties Crystals observed in reflected light are colorless. No varieties of this mineral have been distinguished. ## History and Name The mineral was approved by the IMA in 2007. Its name honors Volker Kahlenberg (born 1964), professor of mineralogy and crystallography at the University of Innsbruck, Austria, for his contributions to research on synthetic and natural compounds with the β-alumina structure, to which kahlenbergite belongs. ## Uses Kahlenbergite has no commercial or industrial applications. Its significance is purely scientific and collectible, especially for collectors specializing in meteorite minerals.

Properties

Luster
Undetermined
Streak
White
Density
3.35
Cleavage
Perfect on {0001}
Transparency
Transparent
Crystal system
Hexagonal

Diagnostic features

## Identification Identification of kahlenbergite is possible only through advanced laboratory methods, such as scanning electron microscopy (SEM) combined with chemical composition analysis (EDS) or electron diffraction. The mineral occurs as microscopic, hexagonal plates. ## Distinguishing from Similar Minerals Due to its unique occurrence environment (inclusions in meteorites) and chemical composition, confusion with other minerals is unlikely at the laboratory analysis stage. It is the potassium analog of diaoyudaoite (NaAl₁₁O₁₇). ## Crystal Forms It forms exclusively microscopic, hexagonal crystals with a tabular or platy habit.

Geological environment

## Genesis Kahlenbergite is a mineral of extraterrestrial origin. It forms in calcium-aluminum-rich inclusions (CAIs) in carbonaceous chondrites. Its presence suggests metamorphic or metasomatic processes involving potassium-rich phases in the very early stages of the Solar System's formation. ## Mineral Associations This mineral has been found in the Allende meteorite. It co-occurs there with hibonite, spinel, perovskite, corundum, and its sodium analog, diaoyudaoite. ## Localities The only confirmed locality for kahlenbergite is the Allende meteorite, which fell in Chihuahua, Mexico, in 1969. This is the type locality for this mineral.

Rarity

Extremely rare

For collectors

## Quality Criteria Kahlenbergite does not form macroscopic specimens. Its value is purely scientific. For specialized collectors, the only way to acquire this mineral is to purchase a fragment of the Allende meteorite with analytically confirmed presence of kahlenbergite in its structure. The value of such a specimen depends on the size of the meteorite fragment and the quality of scientific documentation confirming the mineral's presence.

Care and storage

## Cleaning Specimens containing kahlenbergite, being fragments of meteorites, should not be wet cleaned. Any contaminants should be removed only with compressed air or a very soft brush. ## What to Avoid Avoid contact with water, chemicals, and ultrasound. Meteorites containing this mineral may include phases sensitive to moisture and oxidation. ## Storage Samples should be stored under stable conditions, preferably in a closed, dry container (desiccator) away from dust and moisture, to prevent degradation of both kahlenbergite and associated minerals.

Sources

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