Auroantimonate

Chemical formula: AuSbO<sub>3</sub>

Auroantimonate is a rare gold and antimony oxide, forming microscopic, hexagonal crystals of an intense red color.

## Characteristics Auroantimonate is an oxide mineral composed of gold and antimony. It occurs as extremely small, hexagonal, tabular crystals, rarely exceeding 20 micrometers in diameter. Due to its size, its visual features are observable mainly under high magnification. It forms thin coatings and efflorescences on other minerals. ## Physical Properties Auroantimonate crystals exhibit an intense red color and are transparent. The luster is described as submetallic to adamantine. Due to the microscopic size of the crystals, properties such as hardness or density have not been precisely measured, but only calculated based on structural parameters. ## Colors and Varieties This mineral is characterized by a uniform, deep red color. No color varieties or commercial names are known. ## History and Name The name auroantimonate directly refers to its chemical composition – gold (Latin: *aurum*) and antimony. The mineral was first described in 1999 by A.C. Roberts and co-workers based on material from the Meikle mine in Nevada, USA. Its discovery was approved by the International Mineralogical Association (IMA). ## Uses Auroantimonate has no practical or commercial applications. Its significance is purely scientific and collectible, as a rare and unique representative of gold mineralogy.

Properties

Luster
Sub-metallic
Streak
Red
Density
7.45
Cleavage
Perfect on {0001}
Transparency
Transparent
Crystal system
Trigonal

Diagnostic features

## Identification Identification of auroantimonate in the field is impossible. Under laboratory conditions, it is recognized based on a unique combination of features: intense red color, hexagonal habit of microcrystals, co-occurrence with other gold and antimony minerals, and characteristic chemical composition, confirmed by analytical methods (e.g., EDS). ## Distinguishing from Similar Minerals Due to its color and mode of occurrence, it may be confused with cinnabar (HgS) or realgar (As₄S₄), which also form red coatings. However, differentiation requires advanced chemical analysis, as auroantimonate occurs in paragenesis where these minerals may also be present. ## Crystal Forms It forms very small, hexagonal, tabular crystals, often grouped into rosette aggregates or forming thin coatings and efflorescences on the surface of the host rock or other minerals.

Geological environment

## Genesis Auroantimonate is a secondary mineral, formed in the oxidation zones (gossans) of hydrothermal, gold-bearing ore deposits rich in antimony. It forms under low-temperature conditions as a result of the weathering of primary gold ores and antimony minerals. ## Mineral Associations It co-occurs with other rare secondary minerals, such as stibiconite, tripuhyite, as well as with quartz, barite, stibnite, and native gold. ## Localities The only confirmed and well-documented occurrence of this mineral in the world is its type locality – the Meikle mine in Elko County, Nevada, USA. This is one of the world's most important Carlin-type gold deposits.

Rarity

Extremely rare

For collectors

## Quality Criteria The quality of an auroantimonate specimen is assessed primarily based on the richness and visibility of red coatings or microcrystals on the rock matrix. The most valued samples are those where crystal aggregates are large and distinct enough to be observed under a stereomicroscope. Contrast with a light matrix (e.g., quartz) also enhances the visual appeal of the specimen. ## Popular Localities The only source of collectible specimens is the Meikle mine in Nevada, USA. Specimens from this locality are highly sought after by collectors specializing in systematic and rare minerals, as well as "micromount" specimens.

Care and storage

## Cleaning Specimens with auroantimonate are extremely delicate due to the microscopic nature of the mineral. Cleaning is not recommended, as it can easily remove or damage thin coatings. If absolutely necessary, compressed air can be used from a safe distance to remove dust. ## What to Avoid Any mechanical contact, including touching, rubbing, or using brushes, should be avoided. All chemicals, ultrasonics, and sudden temperature changes should also be avoided. Specimens must not be washed in water. ## Storage Specimens should be stored exclusively in closed, stable "micromount" containers to protect them from dust and mechanical damage. Exposure should be away from vibrations and direct sunlight.

Sources

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