Deloryite

Chemical formula: Cu<sup>2+</sup><sub>4</sub>(U<sup>6+</sup>O<sub>2</sub>)(Mo<sup>6+</sup>O<sub>4</sub>)<sub>2</sub>(OH)<sub>6</sub>

Deloryite is a very rare copper, uranium, and molybdenum mineral, forming characteristic platy crystals of an intense green color.

## Characteristics Deloryite is a complex, hydrated oxide of copper, uranium, and molybdenum. It occurs as very small, thin, platy crystals, often forming rosette-like or radial aggregates. Its most characteristic feature is its intense, emerald-green to almost black color. The crystals are usually too small to be observed with the naked eye and require magnification. ## Physical Properties Deloryite crystals exhibit a vitreous luster. They are transparent to translucent. Due to the small size of the crystals, hardness is difficult to measure precisely but is estimated at about 3 on the Mohs scale. The calculated density is 4.87 g/cm³. ## Colors and Varieties This mineral occurs in shades from emerald-green to greenish-black. No varieties have been distinguished. ## History and Name Deloryite was discovered in the Cap Garonne mine in France. It was described in 1995 by Halil Sarp and Pierre Perroud. The mineral is named in honor of Jean Delory (1929-1992), a French mineral collector who first found samples of this mineral and brought them to the attention of researchers. ## Uses Deloryite has no industrial applications. However, it is a valuable and sought-after collector's mineral, especially among specialists in microminerals and uranium minerals.

Properties

Mohs hardness
3
Luster
Vitreous
Streak
Green
Density
4.87
Cleavage
Perfect on {001}
Fracture
Micaceous
Transparency
Transparent to Translucent
Crystal system
Monoclinic

Diagnostic features

## Identification Deloryite can be identified by its characteristic, intense green color, platy crystal habit, and formation of rosette-like aggregates. It occurs in the oxidation zones of polymetallic deposits, often on sandstone. Due to its size, identification usually requires microscopic magnification. ## Distinguishing from Similar Minerals It can be confused with other secondary copper and uranium minerals, such as torbernite, zeunerite, or schenckite. It differs from torbernite and zeunerite by its monoclinic crystal system (the aforementioned minerals crystallize in the tetragonal system) and different crystal morphology. Final differentiation from other rare minerals in this group requires advanced analyses, e.g., X-ray diffraction (XRD). ## Crystal Forms Crystals are very small, thin, and platy, with a hexagonal or rhombic outline. They typically form radial or rosette-like clusters and aggregates, as well as thin coatings and crusts.

Geological environment

## Genesis Deloryite is a secondary mineral, forming in the oxidation (weathering) zones of polymetallic ore deposits, especially those containing copper, uranium, and molybdenum. It forms as a result of surface water action on primary ore minerals. In its type locality (Cap Garonne), it occurs in voids and fractures in Triassic sandstones impregnated with ore minerals. ## Mineral Associations This mineral co-occurs with other secondary minerals, such as schenckite, brochantite, cyanotrichite, tenorite, malachite, and also with quartz. ## Localities The most important and type locality for deloryite is the Cap Garonne mine in Le Pradet, Var department, France. This is the only confirmed and well-documented locality for this mineral worldwide.

Rarity

Very rare

For collectors

## Quality Criteria The most highly valued deloryite specimens are those with well-formed, sharp crystals forming aesthetic, rosette-like aggregates. An intense, emerald-green color and contrast with the rock matrix are important. Due to the microscopic size of the crystals, specimens are evaluated under magnification. Abundant clusters on the matrix significantly increase the specimen's value. ## Popular Localities The only source of collector specimens is the historical type locality – the Cap Garonne mine in France. Material from this location is extremely rare and sought after by specialized micromineral collectors.

Care and storage

## Cleaning Deloryite specimens are extremely delicate and small. Mechanical cleaning is not recommended. If absolutely necessary, compressed air can be used from a safe distance to remove dust. Avoid contact with water and any chemicals. ## What to Avoid Deloryite is a secondary mineral, potentially soluble in acids. Avoid all chemicals, ultrasonics, and rapid temperature changes. As a uranium-bearing mineral, it is radioactive – store it away from other radiation-sensitive minerals and limit direct exposure. ## Storage It is recommended to store specimens in specialized "micromount" boxes, which protect them from mechanical damage and dust. It should be stored in a dry place, away from direct sunlight and heat sources. Due to its radioactivity, specimens should be appropriately labeled and kept in a location away from permanent human presence.

Sources

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