Pendevilleite-(Y)
Chemical formula: Mg<sub>2</sub>Y<sub>3</sub>Al(U<sup>6+</sup>O<sub>2</sub>)<sub>2</sub>(CO<sub>3</sub>)<sub>7</sub>(OH)<sub>6</sub>(H<sub>2</sub>O)<sub>16</sub>
Pendevilleite-(Y) is an extremely rare, radioactive uranyl and yttrium carbonate mineral, forming microscopic, yellow needle-like crystals and rosettes.
Properties
- Luster
- Vitreous
- Streak
- Yellow
- Transparency
- Transparent
- Crystal system
- Orthorhombic
Diagnostic features
## Identification Identification of Pendevilleite-(Y) is only possible using advanced analytical methods, such as Raman spectroscopy, X-ray diffraction (XRD), and chemical analysis (EDS/WDS). Initial indications may include its intense yellow color, acicular crystal habit, strong green fluorescence under UV-SW, and high radioactivity. However, these features are common to many secondary uranium minerals. ## Distinguishing from Similar Minerals The mineral is visually almost identical to many other secondary uranyl minerals, such as studtite, compreignacite, or other uranyl carbonates. Certain differentiation without specialized analysis is impossible. ## Crystal Forms It forms very fine, acicular to hair-like crystals that combine into radial, stellate, or spherical aggregates (rosettes).
Geological environment
## Genesis It is a secondary mineral, formed in the oxidation zones of uranium deposits. It forms as a result of carbonate-rich waters acting on primary uranium minerals in the presence of aluminum, magnesium, and yttrium. At the type locality, it formed in voids within fossilized wood saturated with uraninite. ## Mineral Associations It co-occurs with other secondary uranium minerals, such as uraninite, gypsum, quartz, calcite, compreignacite, schröckingerite, metazellerite, and liebigite. ## Localities The only confirmed worldwide occurrence is its type locality – the Jomac Mine, located in White Canyon, San Juan County, Utah, USA.
Rarity
Extremely rare
For collectors
## Quality Criteria As a mineral of purely scientific and systematic importance, it is not subject to typical collector evaluation criteria. The value of a specimen depends on the richness of Pendevilleite-(Y) aggregates on the rock matrix and the quality and quantity of associated minerals. Due to its microscopic nature, the certainty of identification confirmed by analysis is paramount.
Care and storage
## Cleaning Due to the extreme rarity, small size, and fragility of specimens, mechanical cleaning is inadvisable and should only be performed by specialists under laboratory conditions. Specimens usually do not require cleaning. ## What to Avoid Avoid contact with water, chemicals, ultrasound, and any mechanical stress. As a uranyl mineral, it is sensitive to changes in humidity and temperature. It is highly radioactive – absolutely avoid inhaling dust and direct skin contact. It requires specialized handling in accordance with radiological protection principles. ## Storage Specimens must be stored in specialized, sealed, and appropriately labeled containers that protect against radiation. They should be kept away from other radiation-sensitive minerals and in a dry, stable environment, away from direct sunlight.