Luobusaite

Chemical formula: Fe₀.₈₄Si₂

Luobusaite is an extremely rare, opaque mineral with a metallic luster, being a naturally occurring iron silicide.

## Characteristics Luobusaite is an iron silicide, one of the few naturally occurring silicides. It forms very small, rounded or irregular grains, usually less than 0.5 mm in size. It is an opaque mineral with a metallic, gray color and a strong luster. ## Physical Properties This mineral is characterized by high hardness, estimated at 6.5-7 on the Mohs scale. It has a metallic luster and is opaque. Its density is significantly higher than average, approximately 6.55 g/cm³. ## History and Name The name Luobusaite comes from its discovery locality – the Luobusa ophiolite in Tibet (China), where it was found in chromitites. It was described and approved as a new mineral by the International Mineralogical Association (IMA) in 2005 (IMA2005-042). ## Uses Due to its extreme rarity and microscopic size, Luobusaite has no industrial applications. It is solely an object of scientific interest and a valuable acquisition for specialized collectors of rare minerals.

Properties

Mohs hardness
6.5-7
Color
steel-gray
Luster
Metallic
Streak
Black
Density
0
Cleavage
None
Fracture
Conchoidal
Transparency
Opaque
Crystal system
Orthorhombic

Diagnostic features

## Identification Identification of luobusaite is impossible without advanced analytical methods, such as scanning electron microscopy (SEM) with chemical composition analysis (EDS/WDS). In collector conditions, identification relies solely on trust in a label from a reliable source that has performed such analyses. ## Distinguishing from Similar Minerals It can be confused with other metallic minerals found in chromitites, such as ferromolybdenum, graphite, or other silicides. Definitive differentiation requires chemical and crystallographic analysis. ## Crystal Forms Luobusaite occurs as anhedral (irregular), rounded grains and aggregates, usually as inclusions in other minerals, primarily chromite.

Geological environment

## Genesis Luobusaite forms under specific, strongly reducing conditions in the Earth's upper mantle. Its presence in subvolcanic ophiolitic chromitites suggests crystallization in an oxygen-poor environment, where silicon could combine with metals such as iron. ## Mineral Associations This mineral coexists with chromite, forsterite, enstatite, diopside, as well as other rare minerals such as gupeiite (Fe₃Si), xifengite (Fe₅Si₃), diamond, moissanite, cohenite, and graphite. ## Localities The only confirmed occurrence of luobusaite in the world is the Luobusa ophiolite massif, located in the Tibetan Autonomous Region in China. This is the type locality for this mineral.

Rarity

Extremely rare

For collectors

## Quality Criteria The quality of a luobusaite specimen primarily depends on the confirmation of its identity through analysis. The size of the grains, although always microscopic, is important – the larger and better-separated the grain, the more valuable the specimen. The aesthetics of the host rock (matrix) are also important. ## Popular Localities The only source of specimens is the Luobusa chromite mine in Tibet. Specimens from this locality, with appropriate analytical documentation, are the only authentic ones on the market.

Care and storage

## Cleaning Specimens containing luobusaite, due to the microscopic size of the grains and their embedding in the host rock, generally do not require cleaning. If necessary, compressed air can be used to remove dust. ## What to Avoid Avoid contact with strong acids, which could damage both the mineral itself and the host rock. There are no specific recommendations regarding temperature or light, but standard caution is advised. ## Storage Specimens should be stored in stable conditions, in a closed "micromount" box, to protect them from dust and mechanical damage. A label with precise locality information is crucial for scientific value.

External references

Sources

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