Wyartite II
Chemical formula: CaU<sup>5+</sup>(U<sup>6+</sup>O<sub>2</sub>)<sub>2</sub>O<sub>4</sub>(OH)·3H<sub>2</sub>O
Wyartite-II is an extremely rare, highly radioactive uranium mineral, forming black, radial aggregates with a metallic luster.
Properties
- Mohs hardness
- 3-4
- Luster
- Metallic to submetallic
- Streak
- Black
- Density
- 5.01
- Cleavage
- Perfect on {001}
- Transparency
- Opaque
- Crystal system
- Orthorhombic
Diagnostic features
## Identification Key diagnostic features of Wyartite-II include its black color, metallic luster, characteristic form of radial aggregates, and very high radioactivity, easily detectable with a Geiger counter. High density is also a helpful feature. ## Distinguishing from Similar Minerals Wyartite-II can be confused with other black, secondary uranium minerals, such as uraninite or some manganese oxides. Uraninite less commonly forms such distinct radial aggregates of platy crystals and often has a pitchy rather than metallic luster. Final and certain differentiation from the very similar Wyartite-I and other rare uraninites requires advanced analytical methods, such as X-ray diffraction (XRD) and chemical composition analysis (EDS). ## Crystal Forms This mineral does not form well-developed, single crystals. It occurs as radial aggregates, rosettes, and crusts, composed of small, flattened bladed or platy crystals.
Geological environment
## Genesis Wyartite-II is a secondary mineral, forming in the oxidation zone of uranium deposits. It is formed as a result of weathering processes and transformations of primary uranium minerals, mainly uraninite, in a calcium-rich environment. ## Mineral Associations This mineral occurs in association with other secondary uranium minerals. The most commonly associated minerals at its only known locality are uraninite, schoepite, becquerelite, and ianthinite. ## Localities The only confirmed occurrence of Wyartite-II in the world is the Shinkolobwe mine in Haut-Katanga Province, Democratic Republic of Congo. This is its type locality.
Rarity
Extremely rare
For collectors
## Quality Criteria The quality of collector specimens of Wyartite-II, which are typically micromounts, is assessed based on several criteria. Specimens with clearly formed, undamaged rosettes or radial aggregates are most desirable. Aesthetic composition with associated minerals is also highly valued, especially if they create a color contrast (e.g., with yellow schoepite). The size and richness of aggregates on the rock matrix also significantly increase the value of the specimen. ## Popular Localities The only source of Wyartite-II specimens is the historic Shinkolobwe mine in the DR Congo. All materials available on the collector's market originate from this single location.
Care and storage
## Cleaning Cleaning Wyartite-II specimens is generally not recommended due to its fragility and radioactivity. If absolutely necessary, a very soft, dry brush can be used to remove dust. Avoid water and all chemical agents. ## What to Avoid The mineral is **highly radioactive**. Direct, prolonged contact, inhalation of dust, and storage near areas of permanent human presence must be strictly avoided. It should not be heated or exposed to chemicals. It is susceptible to abrasion. ## Storage Wyartite-II specimens must be stored in specialized, lead-lined or thick-walled plastic containers that minimize radiation emission. The container must be sealed and clearly marked with the international radioactivity symbol. Store in an isolated location, away from other minerals that could be damaged by radiation (e.g., discoloration of smoky quartz).