Alwilkinsite-(Y)

Chemical formula: Y(U₆+O₂)₃(S₆+O₄)₂O(OH)₃(H₂O)₇·₇H₂O

A very rare, secondary uranium and yttrium mineral, forming yellow, acicular crystals in radial aggregates.

## Characteristics Alwilkinsite-(Y) is a very rare, hydrated uranyl and yttrium sulfate. It occurs as coatings and crusts composed of small, prismatic or acicular crystals. These crystals often form visually attractive, radial or fan-shaped aggregates. Due to the small size of the crystals, it is a mineral primarily valued in the form of micromounts. ## Physical Properties The mineral is characterized by a vitreous luster, transitioning to silky on fibrous aggregates. It is transparent to translucent. The calculated density is approximately 3.69 g/cm³. Hardness has not been precisely determined, but similar to other secondary uranyl sulfates, it is low and estimated at around 2 on the Mohs scale, making it a very brittle and delicate mineral. ## Colors and Varieties Alwilkinsite-(Y) ranges in color from yellow to greenish-yellow. No color varieties or commercial forms are known. ## History and Name The mineral was first described in 2021 by Anthony R. Kampf and co-workers. Its name honors Dr. Alfred "Al" Wilkins (born 1946), an American collector specializing in uranium minerals. The suffix "-(Y)" indicates the dominance of yttrium in the chemical composition. The type locality is the Blue Lizard Mine in San Juan County, Utah, USA. ## Uses Due to its extreme rarity and occurrence in small quantities, alwilkinsite-(Y) has no industrial applications. It is of purely scientific and collector's interest, being a coveted object for specialists collecting uranium minerals and micromounts.

Properties

Luster: Vitreous to Silky
Streak: Light yellow
Density: 3.69
Transparency: Transparent to Translucent
Crystal system: Orthorhombic

Diagnostic features

## Identification Characteristic features of alwilkinsite-(Y) include its yellow color, acicular crystal habit forming radial aggregates, and specific environment of occurrence. The mineral exhibits strong, green fluorescence under ultraviolet light (both longwave and shortwave). A key diagnostic feature is its radioactivity, easily detectable with a Geiger counter. ## Differentiation from Similar Minerals Alwilkinsite-(Y) is visually very similar to many other yellow secondary uranium minerals, such as zippeite, natrozippeite, and johannite. Certain differentiation from these is usually impossible without advanced laboratory analyses, such as X-ray diffraction (XRD) or chemical analysis (EDS). ## Crystal Forms It forms acicular or elongated prismatic crystals, which combine into radial, stellar, or fan-shaped aggregates, and also form crusts and coatings.

Geological environment

## Genesis Alwilkinsite-(Y) is a secondary mineral, formed in the oxidation zones of uranium deposits. It forms under low temperature and pressure conditions as a result of the weathering of primary uranium minerals. It is a typical post-mining mineral, crystallizing on the walls of mine workings in a dry, desert climate. ## Mineral Associations This mineral occurs in association with other secondary uranyl sulfates, primarily gypsum and natrozippeite. It also co-occurs with other rare and often yet unidentified mineral phases. ## Localities The most important and also the type locality for alwilkinsite-(Y) is the Blue Lizard Mine, located in Red Canyon, San Juan County, Utah, USA. This is currently the only confirmed locality for this mineral worldwide.

Rarity

Very rare

For collectors

## Quality Criteria The most prized specimens are those that display well-formed, sharp, and long needles forming aesthetic, radial aggregates on a small rock matrix. The intensity of the yellow color, lack of damage to the delicate crystals, and abundance of the coating significantly increase collector value. Due to the nature of the mineral, most specimens are micromounts. ## Popular Localities The only source of collector specimens is currently the type locality – the Blue Lizard Mine in Utah, USA. Specimens from this locality are highly valued by specialists due to the mineral's rarity and its recent discovery.

Care and storage

## Cleaning Specimens should only be dry-cleaned, using a soft brush or carefully blowing off dust with compressed air. Any contact with water or other liquids should be avoided, as the mineral is soluble in them. ## What to Avoid The mineral is very sensitive to moisture and water. Avoid sudden temperature changes and exposure to direct sunlight, which can lead to dehydration and destruction of the specimen. As a uranium mineral, it is radioactive, and direct contact and exposure time should be limited. Dust is harmful if inhaled. ## Storage Alwilkinsite-(Y) specimens should be stored in dry conditions, in tightly sealed containers (e.g., "perky boxes"), which protect them from moisture and mechanical damage. Due to radioactivity, the collection should be stored away from areas of constant human presence, in a well-ventilated room. Each container must be clearly labeled as containing a radioactive mineral.

Sources

IMA Mineral List (CNMNC)