Furongite

Chemical formula: Al<sub>13</sub>(U<sup>6+</sup>O<sub>2</sub>)<sub>7</sub>(PO<sub>4</sub>)<sub>13</sub>(OH)<sub>14</sub>·58H<sub>2</sub>O

Furongite is a very rare, secondary uranyl mineral, forming bright yellow, microscopic crystals and coatings.

## Characteristics Furongite is a hydrated aluminum and uranyl phosphate, occurring as microscopic, acicular or platy crystals. It forms aggregates in the shape of rosettes, bundles, as well as coatings and encrustations on rocks. Due to the very small size of the crystals, its visual features are difficult to observe without magnification. It has a characteristic bright yellow color. ## Physical Properties Furongite crystals exhibit a silky or dull luster. It is a very soft mineral, with a Mohs hardness of about 2. It is light, with a calculated density of 2.33 g/cm³. It is a strongly radioactive mineral due to its high uranium content. ## Colors and Varieties This mineral occurs in shades from bright yellow to canary yellow. No varieties are distinguished. ## History and Name Furongite was first described in 1976. Its name comes from the Chinese word "Furong," meaning hibiscus, and refers to the type locality – Uranium Mine No. 302 in Hunan Province, China, which is known as the "hibiscus mine." ## Uses Due to its rarity and microscopic size, furongite has no industrial application. It is of purely scientific importance and is an object of interest for specialized collectors of uranium minerals.

Properties

Mohs hardness
2
Luster
Silky
Streak
Light yellow
Density
2.33
Cleavage
Perfect on {100}
Fracture
Uneven
Transparency
Translucent
Crystal system
Monoclinic

Diagnostic features

## Identification Furongite is identified by its characteristic bright yellow color, its occurrence in the form of small, acicular crystals forming coatings and rosettes, and its very strong radioactivity. Identification usually requires advanced analytical techniques, such as X-ray diffraction (XRD). ## Distinguishing from Similar Minerals It can be confused with other secondary yellow uranium minerals, such as meta-autunite, phosphuranylite, or sabugalite. Differentiation with the naked eye is practically impossible. Laboratory tests, which determine the chemical composition and crystal structure, are key for distinction. ## Crystal Forms It forms very small, acicular or platy crystals, which usually do not exceed a fraction of a millimeter in length. These crystals group into rosettes, fan-shaped aggregates, bundles, or form thin, compact coatings on the surface of the host rock.

Geological environment

## Genesis Furongite is a secondary mineral forming in the oxidation zones of uranium deposits. It originates from the weathering and alteration of primary uranium minerals, such as uraninite, in the presence of phosphate- and aluminum-rich waters, derived from the decomposition of surrounding rocks, e.g., granites. ## Mineral Associations It often occurs in association with other secondary uranium minerals, such as meta-autunite, metatorbernite, phosphuranylite, sabugalite, as well as with quartz, kaolinite, and limonite. ## Localities The most important and also the type locality is Uranium Mine No. 302 in the Xincheng region, Hunan Province, China. It has also been identified in several other localities worldwide, including the Margnac mine in France and the uranium mine near Jáchymov in the Czech Republic.

Rarity

Very rare

For collectors

## Quality Criteria The most desirable specimens for collectors are those with clearly formed, albeit microscopic, crystalline aggregates (rosettes, bundles) on a contrasting host rock background. The intensity and purity of the yellow color also affect the attractiveness of the specimen. Due to its microscopic nature, the quality of the "micromount" preparation is crucial. ## Popular Localities The most classic and valued specimens come from the type locality in Hunan Province, China. Specimens from European localities, such as France or the Czech Republic, are also sought after by specialists.

Care and storage

## Cleaning This mineral is extremely delicate and fragile. It should not be cleaned mechanically or chemically. Any attempts at cleaning may irreversibly damage the specimen. ## What to Avoid Contact with water, which can dissolve or damage the microscopic crystals, should be strictly avoided. It should be protected from shocks, impacts, high temperatures, and direct sunlight. As a uranium mineral, it is strongly radioactive and requires special precautions. Avoid inhaling dust and direct skin contact. Wash hands thoroughly after each contact. ## Storage Furongite specimens must be stored in sealed, lead-lined, or appropriately shielded containers away from human presence to minimize radiation exposure. It is best stored in specialized "micromount" boxes, which protect delicate crystals from mechanical damage.

Sources

Read more