Curienite
Chemical formula: Pb<sup>2+</sup>(U<sup>6+</sup>O<sub>2</sub>)<sub>2</sub>(V<sup>5+</sup>O<sub>4</sub>)<sub>2</sub>·5H<sub>2</sub>O
Curienite is a rare uranyl vanadate mineral with an intense, yellow-orange color, occurring in the oxidation zones of uranium deposits.
Properties
- Mohs hardness
- 2
- Luster
- Adamantine, Dull
- Streak
- Yellow
- Density
- 4.88 - 5.09
- Cleavage
- Perfect on {010}
- Fracture
- Uneven
- Transparency
- Translucent
- Crystal system
- Orthorhombic
Diagnostic features
## Identification Curienite is identified by its intense, yellow-orange color, characteristic crusts, and small, platy crystals. Key is its occurrence in paragenesis with other secondary uranium and vanadium minerals. It is strongly radioactive, which is easily verifiable with a Geiger counter. ## Distinguishing from Similar Minerals It can be confused with other secondary uranium minerals of similar color, such as carnotite, tyuyamunite, or francevillite. Carnotite and tyuyamunite have similar colors but differ in chemical composition (presence of potassium or calcium instead of lead) and subtly in physical properties. Francevillite, with which it often co-occurs, contains barium and has a slightly different hue and crystal forms. Precise identification requires advanced analytical methods (XRD, EDS). ## Crystal Forms Crystals are very small, platy or acicular, often flattened. They usually form radial aggregates, rosettes, crusts, or earthy and powdery aggregates on the surface of the host rock.
Geological environment
## Genesis Curienite is a secondary mineral, forming in the oxidation zones of uranium-vanadium deposits that also contain lead sulfides (e.g., galena). It forms as a result of the weathering of primary uranium and vanadium minerals in the presence of lead-rich solutions. ## Mineral Associations It most commonly co-occurs with francevillite, chervetite, duttonite, as well as with uraninite, galena, quartz, and clay minerals. It occurs in association with other secondary uranium and vanadium minerals. ## Localities The most important and classic locality, which is the type locality, is the Mounana mine in Haut-Ogooué Province, Gabon. It is also known from the uranium mine in the Lodève region of France and from several locations in the Czech Republic (e.g., Zálesí in the Jeseníky Mountains).
Rarity
Rare
For collectors
## Quality Criteria The most prized curienite specimens are those with well-formed, though still microscopic, crystals forming rich, lustrous crusts of an intense orange color. Contrast with dark host rock enhances visual appeal. Association with other rare minerals, especially well-crystallized francevillite, is also important. ## Popular Localities Specimens from the type locality – the Mounana mine in Gabon – are by far the most sought after by collectors. They are considered classic and exemplary for this mineral.
Care and storage
## Cleaning Curienite specimens should not be cleaned wet. Dust and loose contaminants can only be removed with a soft brush or a stream of compressed air from a safe distance. ## What to Avoid Contact with water and any chemicals must be strictly avoided. The mineral is sensitive to changes in humidity and temperature. As a uranium mineral, it is radioactive and potentially harmful – avoid inhaling dust and direct skin contact. Hands should be thoroughly washed after each contact with a specimen. ## Storage Curienite specimens should be stored in sealed, airtight containers (e.g., “perky box” type) to reduce the risk of dusting and protect them from moisture. They should be kept away from areas of permanent human habitation, in a dry and temperature-stable environment. They must be appropriately labeled as radioactive material.