Zincorietveldite
Chemical formula: Zn<sup>2+</sup>(U<sup>6+</sup>O<sub>2</sub>)(S<sup>6+</sup>O<sub>4</sub>)<sub>2</sub>(H<sub>2</sub>O)<sub>5</sub>
Zincurietveldtite is a very rare, secondary uranyl mineral, being the zinc analogue of rietveldite.
Properties
- Mohs hardness
- 2
- Luster
- Vitreous to Pearly
- Streak
- Light yellow
- Density
- 3.55
- Cleavage
- Perfect on {010}
- Fracture
- Unknown
- Transparency
- Translucent
- Crystal system
- Orthorhombic
Diagnostic features
## Identification Key diagnostic features include its light yellow to yellowish-green color, habit in the form of small, radial aggregates of acicular or bladed crystals, and very strong radioactivity. It occurs in association with other secondary uranium minerals. ## Distinguishing from Similar Minerals It can be confused with other secondary uranyl minerals of similar color and habit, such as rietveldite, zippeite, or johannite. Differentiation requires advanced analytical methods, such as chemical analysis (EDS/WDS) to confirm the dominance of zinc over iron (unlike rietveldite) or magnesium (unlike magnesiozippeite). ## Crystal Forms Zincurietveldtite forms elongated, bladed crystals that combine into radial, spherical, or hemispherical aggregates and rosettes.
Geological environment
## Genesis It is a secondary mineral, formed in the oxidation zones of uranium deposits. It forms as a result of weathering and alteration of primary uranium minerals (e.g., uraninite) in the presence of sulfate- and zinc-rich solutions. It forms under low temperature and pressure conditions, often as coatings and crusts on host rocks. ## Mineral Associations It co-occurs with other secondary uranyl minerals and sulfates. In its type locality (Blue Lizard mine), it was found in association with gypsum, rietveldite, fermiite, meyerite, metavoltaite, opal (hyalite variety), pyrite, and a number of other, yet unnamed uranyl phases. ## Localities The only confirmed and described locality for zincurietveldtite worldwide is its discovery site – the Blue Lizard mine, Red Canyon, San Juan County, Utah, USA.
Rarity
Extremely rare
For collectors
## Quality Criteria As a microscopic mineral, the quality of a specimen is primarily determined by the richness and aesthetics of the crystal aggregates on the rock matrix. The most desirable specimens are those with well-formed, distinct rosettes or radial clusters of intense, yellowish-green color, contrasting with the substrate. The size of the crystals, though always small, also affects the value. ## Popular Localities The only source of specimens is the Blue Lizard mine in Utah, USA. Specimens from this locality are unique and define the species.
Care and storage
## Cleaning The mineral is extremely brittle and sensitive. Mechanical cleaning is not recommended. If absolutely necessary, a stream of compressed air from a distance can be used to remove loose dust particles. ## What to Avoid Contact with water and chemicals, which can dissolve or damage the delicate crystals, must be strictly avoided. The mineral is sensitive to changes in temperature and humidity. As a uranyl mineral, it is strongly radioactive and requires specialized precautions. It should not be stored without proper shielding and knowledge of handling radioactive materials. ## Storage Specimens must be stored in specialized, lead-lined or thick-glass containers to minimize radiation emission. The container should be airtight to protect the mineral from moisture and prevent the spread of radon dust. Store away from other minerals that may be sensitive to radiation.