Beckettite

Chemical formula: Ca<sub>2</sub>V<sup>3+</sup><sub>6</sub>Al<sub>6</sub>O<sub>20</sub>

Beckettite is an extremely rare mineral from the hibonite group, found exclusively in the Allende meteorite, distinguished by its unique chemical composition with vanadium.

## Characteristics Beckettite is a microscopic mineral, occurring as small, tabular crystals with a hexagonal outline. It typically forms aggregates with other rare minerals within calcium-aluminum-rich inclusions (CAIs) in meteorites. Its crystals rarely exceed 50 micrometers in size. It is opaque and has a black color with a metallic luster. ## Physical Properties Due to the microscopic size of the crystals, most physical properties, such as hardness, density, or fracture, have not been precisely measured, but only estimated based on comparisons with similar minerals from the hibonite supergroup. The luster is described as metallic to submetallic. ## Colors and Varieties The mineral is black. No color varieties or commercial varieties have been distinguished. ## History and Name Beckettite was officially recognized as a new mineral by the International Mineralogical Association (IMA) in 2008 (IMA2008-055). Its name honors John R. Beckett, a researcher at the California Institute of Technology (Caltech), for his contributions to experimental research on CAIs in meteorites. The mineral was discovered and described by Chi Ma and George R. Rossman. ## Applications Beckettite has no commercial or industrial applications. Its significance is purely scientific, as an indicator of conditions in the early Solar System.

Properties

Mohs hardness
7-8
Luster
Metallic
Streak
Black
Density
4.35
Cleavage
Perfect on {0001}
Transparency
Opaque
Crystal system
Hexagonal

Diagnostic features

## Identification Identification of beckettite is impossible without advanced laboratory techniques. It requires the use of a scanning electron microscope (SEM) and energy-dispersive spectroscopy (EDS) or an electron microprobe (EMPA) to precisely determine the chemical composition of a given microcrystal. Visual features, such as black color and hexagonal outline, are merely indicative. ## Distinguishing from similar minerals It can be confused with other black, opaque minerals from the hibonite supergroup, such as hibonite, grossmanite, or tistarite, which occur in the same environment. Definitive distinction is possible only based on chemical analysis, which shows the unique dominance of vanadium and aluminum with the presence of calcium for beckettite. ## Crystal forms Beckettite forms very small, tabular crystals with a hexagonal outline. These crystals typically do not exceed 50 µm in length and 10 µm in thickness.

Geological environment

## Genesis Beckettite is an extraterrestrial mineral. It forms by crystallization from a high-temperature gas in the protosolar nebula. It is one of the primary, ultra-refractory components of calcium-aluminum-rich inclusions (CAIs) in carbonaceous chondrites. ## Mineral associations This mineral occurs in close association with other minerals typical of CAIs. It most commonly co-occurs with spinel, perovskite, hibonite, grossmanite, and davisite. ## Localities The only confirmed locality for beckettite in the world is the Allende meteorite. This is a CV3 type carbonaceous chondrite that fell in Chihuahua, Mexico, in 1969. The mineral was found within a CAI named "Curious Marie."

Rarity

Extremely rare

For collectors

## Quality criteria The quality of a beckettite specimen is assessed solely in a scientific context. Key factors are its unambiguous identification through chemical analysis and the degree of development of its microscopic crystals. Since the mineral is embedded in a matrix, the mineralogical context – i.e., associations with other rare minerals – is also important. These specimens are virtually unavailable on the commercial market and are primarily found in research institutions. ## Popular localities The only source is the Allende meteorite (Mexico), specifically the CAIs found within its fragments.

Care and storage

## Cleaning Specimens containing beckettite, due to their microscopic nature and embedding in the meteorite matrix, are not subject to cleaning in the traditional sense. Any attempts at cleaning could irrevocably destroy the mineral and its surroundings. The preparation of such samples is carried out exclusively in specialized laboratories. ## What to avoid Absolutely everything should be avoided: contact with chemicals, moisture, temperature changes, and above all, any mechanical interactions. Samples are extremely sensitive. ## Storage Specimens with beckettite should be stored under stable conditions, preferably in specialized membrane containers or in sealed containers with a controlled atmosphere, away from light, dust, and vibrations. These are materials of museum and scientific value.

Sources

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