Xiangjiangite

Chemical formula: Fe³⁺(U⁶⁺O₂)₄(PO₄)₂(S⁶⁺O₄)₂(OH)·₂₂H₂O

Xiangjiangite is a rare, secondary uranium mineral characterized by its distinctive light yellow to greenish-yellow color, found in the oxidation zones of uranium deposits.

## Characteristics Xiangjiangite is a hydrated uranyl iron sulfate-phosphate. It is a secondary mineral, meaning it forms as a result of the weathering and oxidation of pre-existing uranium minerals. It occurs as earthy, powdery, or dusty coatings and aggregates, as well as crusts on other minerals. Due to its nature, well-formed crystals are extremely rare and appear as tiny, scaly platelets. ## Physical Properties This mineral is very soft and light. Its crystals, if visible, exhibit a pearly luster on cleavage surfaces, while earthy aggregates are dull. It is transparent to translucent in individual, microscopic crystals. ## Colors and Varieties Xiangjiangite has a characteristic light yellow, greenish-yellow to lemon-yellow color. No color or commercial varieties are distinguished. ## History and Name The mineral was discovered in 1978 in the Chashan uranium mine in Hunan Province, China. Its name comes from the Xiang River (Xiangjiang), which flows through this province. It was approved by the International Mineralogical Association (IMA) in the same year. ## Uses Due to its rarity and occurrence in small quantities, xiangjiangite has no industrial application. It is of purely scientific and collector interest, being a subject of interest for specialists in uranium minerals.

Properties

Mohs hardness: 1-2
Color: Yellow.
Luster: Silky, earthy
Streak: Light yellow
Density: 2.9
Cleavage: Perfect on {001}
Fracture: Uneven
Transparency: Translucent
Crystal system: Tetragonal

Diagnostic features

## Identification Key diagnostic features include its light yellow to greenish-yellow color, earthy or scaly habit, and strong fluorescence under UV light. Its radioactivity, detectable with a Geiger counter, is also a characteristic feature. It occurs in the typical environment of oxidation zones of uranium deposits. ## Distinguishing from Similar Minerals It can be confused with many other yellow secondary uranium minerals, such as autunite, uranophane, carnotite, or tyuyamunite. Differentiation is often impossible without advanced research methods (chemical analysis, X-ray diffraction). Its exceptional softness and tendency to form dusty coatings can be a clue. ## Crystal Forms It forms microscopic, thin, scaly or platy crystals, often with a square or hexagonal outline. Most often, it occurs as very fine-grained, earthy, dusty, or powdery aggregates and coatings.

Geological environment

## Genesis Xiangjiangite is a secondary mineral, forming in the oxidation zones of hydrothermal uranium deposits located in granitic or sedimentary rocks. It forms as a result of the weathering and alteration of primary uranium minerals, such as uraninite, under conditions rich in oxygen, water, and phosphate and sulfate ions. ## Mineral Associations It most commonly co-occurs with other secondary uranium minerals, such as uranophane, metauranocircite, saleeite, torbernite, as well as with quartz, gypsum, kaolinite, and limonite. ## Localities The most important and type locality is the Chashan uranium mine in Hunan Province, China. It has also been identified in several other locations worldwide, including a uranium mine near Lodève in France and the White Canyon mine in San Juan County, Utah, USA.

Rarity

Rare

For collectors

## Quality Criteria The collector appeal of xiangjiangite primarily depends on the saturation and vividness of its yellow color and the richness of the coating on the host rock. Specimens with visible, even under a microscope, scaly crystals are much more valued than the more common earthy aggregates. The size of the specimen and aesthetic contrast with a darker host rock also increase its value. ## Popular Localities By far the most sought-after specimens by collectors come from the type locality – the Chashan mine in China. Material from other localities, such as Lodève in France or White Canyon in the USA, is also valued due to its rarity.

Care and storage

## Cleaning The mineral is extremely delicate, soft, and water-soluble. It must absolutely not be cleaned wet. Any dust can only be removed very carefully with a soft brush or a stream of compressed air from a distance. ## What to Avoid Avoid contact with water and any liquids that will dissolve it. Avoid vibrations, shocks, and abrasion due to its low hardness. As a uranium mineral, it is radioactive – limit exposure, avoid inhaling dust, and wash hands after any contact. Do not store in bedrooms or areas of permanent human presence. ## Storage Specimens should be stored in sealed, transparent containers (perky boxes) that protect them from mechanical damage, dust, and moisture, and also limit radon dispersion. The container should be clearly labeled as radioactive material.