Domerockite

Chemical formula: Cu²⁺₄(As⁵⁺O₄)(As⁵⁺O₃OH)(OH)₃·H₂O

Domerockite is a rare, hydrated hydroxyl arsenate of copper, forming aggregates of small, blue-green crystals.

## Characteristics Domerockite is a very rare secondary mineral from the arsenate group. It occurs as microscopic, bladed or tabular crystals that form rosette-like aggregates, spherulitic clusters, or thin crusts. Due to the small size of the crystals, its features are difficult to observe with the naked eye, and specimens appear as earthy or fibrous masses. ## Physical Properties Domerockite crystals are translucent and have a hardness of 3 on the Mohs scale. Their density is approximately 4.44 g/cm³. This mineral does not exhibit cleavage, and its fracture is uneven. ## Colors and Varieties Domerockite has a characteristic, uniform blue-green color. No color varieties or commercial forms are known. ## History and Name The mineral's name comes from its discovery locality – the Dome Rock copper mine in South Australia. It was first described in 1976 by I.R. Harrowfield, W.G. Mumme, E.E. Moser, and I.E. Segnit. ## Applications Due to its extreme rarity and occurrence only in microscopic aggregates, domerockite has no industrial applications. It is solely an object of interest for collectors specializing in rare minerals and for scientists.

Properties

Mohs hardness
3
Luster
Vitreous
Streak
Pale green
Density
4.44
Cleavage
No mention of cleavage.
Fracture
Irregular/Uneven
Transparency
Translucent
Crystal system
Triclinic

Diagnostic features

## Identification Identification of domerockite under amateur conditions is practically impossible and requires advanced analytical methods, such as X-ray diffraction (XRD) or spectroscopy. Preliminary identification is based on its blue-green color, mode of occurrence (spherulitic aggregates), and association with other secondary copper and arsenic minerals in oxidation zones. ## Distinguishing from Similar Minerals Domerockite can be confused with many other secondary copper minerals of similar color, such as olivenite, euchroite, cyanotrichite, or brochantite. Key to differentiation is the examination of chemical composition and crystal structure, as visual features are often ambiguous. ## Crystal Forms This mineral forms very small, bladed crystals that combine into spherulitic or rosette-like aggregates. It also occurs as thin coatings and crusts on the host rock.

Geological environment

## Genesis Domerockite is a secondary mineral, forming in the oxidation zones (so-called gossans) of copper and arsenic ore deposits. It forms as a result of the weathering of primary minerals containing these elements in a dry, desert climate. ## Mineral Associations This mineral occurs in association with other rare secondary minerals. At its type locality, it was found together with olivenite, chenevixite, cornwallite, arthurite, quartz, hematite, and goethite. ## Localities The only confirmed and well-documented occurrence of domerockite in the world is its type locality – the Dome Rock copper mine in the Boolcoomatta Reserve, South Australia.

Rarity

Extremely rare

For collectors

## Quality Criteria The quality of a domerockite specimen is primarily assessed based on the richness and aesthetics of the aggregates on the host rock. The most valued specimens are those with clearly formed, spherical or rosette-like clusters of intense, blue-green color, contrasting with the rock matrix. Due to the microscopic nature of the crystals, the size of individual specimens is not a key criterion – the overall presentation and surface coverage are what matter. ## Popular Localities The only source of domerockite specimens is its type locality – the Dome Rock mine in South Australia. All samples available on the collector's market originate from this single locality.

Care and storage

## Cleaning Due to its fragility and occurrence in the form of delicate aggregates, mechanical cleaning is not recommended. Only careful dust removal with a soft brush or a photographic air blower is permissible. Contact with water and any chemicals should be avoided. ## What to Avoid Domerockite specimens are sensitive to shocks, abrasion, and acids. They should be protected from moisture, sudden temperature changes, and direct sunlight, which can lead to fading. ## Storage It is recommended to store specimens in stable conditions, in closed, padded "micromount" boxes to protect them from mechanical damage, dust, and moisture. Display should be away from sources of vibration and direct lighting.

External references

Sources

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