Paraschoepite

Chemical formula: U₆+O₃·(₂-x)H₂O

Paraschoepite is a rare, secondary uranium mineral that forms as a weathering product of uraninite and is distinguished by its intense yellow color.

## Characteristics Paraschoepite is a mineral from the uranyl hydroxide group, formed by the oxidation and hydration of uraninite in the weathering zones of uranium deposits. Typical specimens appear as microcrystalline, earthy, or powdery coatings and aggregates on the parent uraninite. Less commonly, it forms small, tabular or bladed crystals with an intense yellow, yellowish-orange, or straw-yellow color. Due to its nature, it is highly radioactive. ## Physical Properties Paraschoepite crystals, though rare, exhibit a vitreous to pearly luster on cleavage surfaces. The mineral is translucent to opaque. Its Mohs hardness is approximately 2.5, and its density is high, approximately 4.54 g/cm³. ## Colors and Varieties This mineral occurs in various shades of yellow – from lemon-yellow, through straw-yellow, to yellowish-orange. No distinct commercial or color varieties are distinguished. ## History and Name Paraschoepite was first described in 1947 by Clifford Frondel and Alice D. Weeks. Its name refers to the Greek word *παρά* (para), meaning "beside" or "near," and to the mineral schoepite, with which it is closely related chemically and structurally, and often co-occurs. It was distinguished from schoepite based on crystallographic studies. ## Uses Paraschoepite has no industrial application. Its significance is limited to the scientific sphere, as an indicator of weathering processes in uranium deposits, and to a narrow group of specialized collectors of radioactive minerals.

Properties

Mohs hardness: 2.5
Luster: Vitreous
Streak: Yellow
Density: 4.54
Cleavage: Perfect on {001}
Fracture: Uneven
Transparency: Translucent to opaque
Crystal system: Orthorhombic

Diagnostic features

## Identification The key diagnostic feature of paraschoepite is its intense yellow color, occurrence as coatings on uraninite, and strong radioactivity, easily detectable with a Geiger counter. Under ultraviolet light (both shortwave and longwave), it exhibits strong, greenish-yellow fluorescence. ## Distinguishing from Similar Minerals It can be confused with other yellow secondary uranium minerals, such as schoepite, metaschoepite, fourmarierite, or becquerelite. Distinguishing it from schoepite is particularly difficult and often requires advanced analytical methods, such as X-ray diffraction (XRD), as paraschoepite is its polymorph. In field conditions, distinguishing it from these minerals is practically impossible. ## Crystal Forms Paraschoepite most often forms microcrystalline, earthy, or powdery coatings and crusts. Less commonly, it is found as small, tabular crystals with a rectangular or bladed outline, which can form rosette-like or radial aggregates.

Geological environment

## Genesis Paraschoepite is a secondary mineral, forming exclusively in the oxidation (weathering) zones of uranium deposits. It forms as a result of the hydration and alteration of primary uraninite (UO₂) under the influence of oxygen-rich waters. It is an intermediate product in the complex sequence of uranyl mineral transformations. ## Mineral Associations It most often co-occurs with its parent mineral – uraninite. It is also accompanied by other secondary uranium minerals, such as schoepite, becquerelite, fourmarierite, ianthinite, as well as gypsum, calcite, and clay minerals. ## Localities Significant localities from which well-formed specimens originate include primarily the Shinkolobwe mine in the Democratic Republic of Congo (type locality), Great Bear Lake in Canada, and deposits in the Athabasca Lake region (Saskatchewan, Canada). It also occurs in numerous other locations worldwide where uranium deposits have been exploited, including Utah (USA) and the Czech Republic.

Rarity

Rare

For collectors

## Quality Criteria For collectors of radioactive minerals, the most desirable specimens are those with visible, well-formed paraschoepite crystals, which are very rare. Rich, intensely colored coatings with a vibrant yellow hue, contrasting with a dark uraninite matrix, are also highly valued. Precise documentation of the locality is important, as scientific and collector value is closely linked to it. ## Popular Localities The most classic and prized specimens come from historical finds in the Shinkolobwe mine in Congo. Specimens from Canadian localities, especially from the Great Bear Lake region, are also highly regarded in specialized collections.

Care and storage

## Cleaning Due to its fragility and solubility, mechanical or chemical cleaning is highly inadvisable. Specimens should be protected from dust and contaminants by storing them in sealed containers. Any dust removal should be done with the utmost care, preferably using a soft brush, while simultaneously employing appropriate personal protective equipment due to radioactivity. ## What to Avoid Contact with water and other liquids, which can dissolve or chemically alter the mineral, must be strictly avoided. It is sensitive to changes in temperature and humidity. Prolonged exposure to sunlight can cause dehydration and transformation into other, more stable uranium oxides, often accompanied by a change in color to a darker shade. As a highly radioactive mineral, it requires specialized and safe handling. ## Storage Paraschoepite specimens must be stored in dry, airtight, and appropriately labeled containers, preferably away from other minerals that could suffer radiation damage. They should be kept in a location with stable, low humidity and temperature, with restricted access, in accordance with regulations for radioactive materials.

Sources

IMA Mineral List (CNMNC)