Carletonmooreite

Chemical formula: Ni<sub>₃</sub>Si

Carletonmooreite is an extremely rare nickel silicide, identified in the Butler iron meteorite, distinguished by its metallic appearance.

## Characteristics Carletonmooreite is a nickel silicide with a metallic, opaque appearance. It has been observed as microscopic, rounded grains up to 100 micrometers in size, occurring in association with other nickel-silicon minerals within the meteorite. Its identification requires advanced analytical techniques, such as electron spectroscopy and X-ray diffraction, due to its small size and occurrence within a complex mineral matrix. ## Physical Properties This mineral is characterized by high hardness, estimated at 6-7 on the Mohs scale, which is typical for intermetallic compounds. It has a metallic luster and is opaque. Its density, calculated based on its chemical composition and unit cell parameters, is 7.53 g/cm³. ## History and Name Carletonmooreite was officially recognized as a new mineral by the International Mineralogical Association (IMA) in 2019 (IMA2019-053). The name honors Carleton B. Moore (born 1932), retired professor and founding director of the Center for Meteorite Studies at Arizona State University, in recognition of his significant contributions to meteorite research. The mineral was discovered and described by a team of scientists studying the Butler iron meteorite, found in 1971 in Butler County, Missouri, USA. ## Applications Due to its extreme rarity and microscopic size, carletonmooreite has no practical or commercial applications. Its significance is purely scientific, providing information about mineralogical processes occurring in extraterrestrial conditions, within the parent bodies of asteroids.

Properties

Mohs hardness: 6-7
Luster: Metallic
Streak: Black
Density: 7.53
Cleavage: None
Fracture: Uneven
Transparency: Opaque
Crystal system: Tetragonal

Diagnostic features

## Identification Identification of carletonmooreite is impossible without specialized laboratory equipment. It requires analysis using an electron microscope with energy-dispersive spectrometry (EDS/WDS) to determine chemical composition, and X-ray diffraction (XRD) or electron backscatter diffraction (EBSD) to confirm crystal structure. Visually, it is simply a microscopic, metallic grain embedded in the meteorite matrix. ## Distinguishing from Similar Minerals It can be confused with other nickel silicides found in the same meteorite, such as perryite ((Ni,Fe)₈(Si,P)₃) or suessite ((Fe,Ni)₃Si). Differentiation relies solely on precise analysis of the nickel-to-silicon ratio and structural parameters. It is distinguished from the surrounding metallic iron-nickel (kamacite, taenite) by the presence of silicon as a major non-metallic component. ## Crystal Forms Carletonmooreite occurs as anhedral (irregular), rounded grains not exceeding 100 micrometers in size.

Geological environment

## Genesis Carletonmooreite is a mineral of extraterrestrial origin. It formed within the asteroid from which the Butler iron meteorite (IAB-ung classification) originated. It is believed to have formed as a result of reduction processes at very high temperatures and low pressures, where silicon, instead of forming typical silicate minerals, reacted with metallic nickel to form silicides. Such conditions are impossible to achieve in a natural terrestrial environment. ## Mineral Associations This mineral occurs in close association with other metallic phases and silicides in the Butler meteorite. Its immediate surroundings include kamacite (Fe,Ni), taenite (Ni,Fe), schreibersite ((Fe,Ni)₃P), cohenite ((Fe,Ni,Co)₃C), as well as other rare nickel silicides, such as perryite and suessite. ## Localities The only confirmed locality of carletonmooreite in the world is the Butler iron meteorite, found in Butler County, Missouri, USA. This is the type locality for this mineral.

Rarity

Extremely rare

For collectors

## Quality Criteria Specimen quality for carletonmooreite is a purely scientific concept. Since the mineral is invisible to the naked eye, collectible value pertains to the entire fragment of the Butler meteorite. The attractiveness of such a fragment depends on its size, degree of preservation (lack of corrosion), and the presence and clarity of Widmanstätten structures. Analytically confirmed presence of carletonmooreite in a given fragment increases its scientific and potentially market value for specialized meteorite collectors. ## Popular Localities The only source of this mineral is the Butler meteorite (Missouri, USA). Fragments of this meteorite are extremely rare on the collector's market and are mainly found in institutional and research collections.

Care and storage

## Cleaning Specimens containing carletonmooreite (i.e., fragments of the Butler meteorite) should not be wet cleaned. Dust can only be removed using a soft brush or compressed air from a safe distance. ## What to Avoid Contact with water, chemicals, acids, and cleaning agents should be strictly avoided, as they can react with associated minerals (mainly metallic iron and nickel), leading to corrosion and destruction of the sample. The specimen should be protected from moisture and high humidity, which accelerates oxidation processes. ## Storage Meteorite fragments containing carletonmooreite must be stored under controlled, low humidity conditions. It is best to use sealed containers (e.g., membrane boxes or perky boxes) with a desiccant, such as silica gel. Store at a stable temperature, away from direct sunlight.

Sources

IMA Mineral List (CNMNC)