Sarrabusite

Chemical formula: Pb²⁺₅Cu²⁺(Se⁴⁺O₃)₄Cl₄

Sarrabusite is a very rare lead-copper selenite with a characteristic lemon-yellow color, found as tiny, acicular crystals.

## Characteristics Sarrabusite is a selenite mineral, chemically a lead-copper selenite with chlorine. It occurs as very small, elongated, acicular or hair-like crystals, rarely exceeding 1 mm in length. It forms radial or tangled aggregates. Its most characteristic feature is its intense, lemon-yellow color. ## Physical Properties Sarrabusite crystals are translucent and exhibit a white streak. Due to the extreme rarity and small size of the crystals, properties such as hardness, luster, or density have not been fully determined or are estimated. The density calculated based on the formula and unit cell parameters is 6.011 g/cm³. ## Colors and Varieties This mineral is monochromatic and occurs exclusively in a lemon-yellow hue. No color or commercial varieties are known. ## History and Name Sarrabusite was discovered in the Baccu Locci mine in Italy and described in 1999. Its name comes from the Sarrabus region in Sardinia, where its type locality (Baccu Locci mine) is located. This is the only confirmed occurrence of this mineral in the world. ## Uses Sarrabusite has no industrial application. Due to its extreme rarity, attractive color, and crystal form, it is a highly prized collector's mineral, sought after by specialized collectors of rare minerals and micromounts.

Properties

Streak
White
Density
6.011
Transparency
Translucent
Crystal system
Monoclinic

Diagnostic features

## Identification Sarrabusite is recognizable by a unique combination of features: lemon-yellow color, acicular or hair-like crystal form creating radial aggregates, and occurrence in oxidation zones of selenium deposits. Its extreme rarity and occurrence in only one locality worldwide are key indicators. ## Distinguishing from Similar Minerals It may be confused with other rare, yellow secondary minerals, such as anglesite-mimetite or some uranophanes, but its characteristic acicular habit and selenium-related genesis allow for differentiation. Precise identification requires advanced analytical methods, such as Raman spectroscopy or chemical analysis (EDS). ## Crystal Forms Sarrabusite crystals are strongly elongated, acicular, often slightly flattened. They typically form small, radial or haphazardly tangled aggregates on the surface of the host rock.

Geological environment

## Genesis Sarrabusite is a secondary mineral, formed in the oxidation zones (gossans) of hydrothermal polymetallic deposits rich in selenium. It forms as a result of the weathering of primary ores containing lead, copper, and selenium in the presence of chloride ions. ## Mineral Associations This mineral co-occurs with other secondary selenite and sulfate minerals. At its type locality, it was found in association with anglesite, chalcomenite, olivenite, kermesite, and iron oxides (goethite, hematite). ## Localities The only confirmed and described occurrence of sarrabusite in the world is its type locality – the Baccu Locci mine in Villaputzu, in the Province of South Sardinia, Italy.

Rarity

Extremely rare

For collectors

## Quality Criteria The most highly valued sarrabusite specimens are those with rich, dense clusters of well-formed, lemon-yellow needles, forming aesthetic, radial aggregates. Contrast with the dark host rock and the absence of damage to delicate crystals are also important. Due to their microscopic size, specimens are primarily evaluated under magnification. ## Popular Localities The only source of sarrabusite specimens is its type locality: the Baccu Locci mine in Sardinia, Italy. All specimens available on the collector's market originate from this single location.

Care and storage

## Cleaning Sarrabusite specimens are extremely delicate and small. Mechanical cleaning should be avoided. If absolutely necessary, compressed air can be used from a safe distance to remove dust. Contact with water or other chemicals is not recommended. ## What to Avoid Avoid contact with any liquids and chemicals that may react with selenites or chlorides. The mineral is sensitive to shocks and mechanical damage – acicular crystals are easily destroyed. Protect it from high temperatures and sudden temperature changes. ## Storage The safest method for storing sarrabusite is to place it in a specialized micromount box that protects the specimen from dust, moisture, and mechanical damage. Display should be away from direct sunlight and heat sources.

External references

Sources

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