Xianhuaite-(La)

Chemical formula: K₂LaNb₅+₅O₁₅

A very rare potassium lanthanum niobate discovered in the famous Bayan Obo rare-earth element deposit in China.

## Characteristics Xianhuaite-(La) is an extremely rare mineral that is a complex potassium lanthanum niobate with the formula K₂LaNb₅O₁₅. It crystallizes in the tetragonal system. Due to its occurrence as microscopic grains, visual identification without specialized laboratory equipment is impossible. It belongs to a group of very rare mineral phases discovered in deposits enriched in rare-earth elements. ## Physical properties Detailed physical properties of this mineral are difficult to determine macroscopically due to its extreme rarity and microscopic crystal size. Identification relies on structural and chemical studies. ## Colors and varieties No known varieties. ## History and name The mineral was discovered in the famous Bayan Obo deposit in China, which is one of the world's largest sources of rare-earth metals. The suffix "-(La)" in the name (according to Levinson's modifier system for rare-earth minerals) indicates lanthanum as the dominant rare-earth element in its crystal structure. ## Uses Due to its extreme rarity, this mineral has no industrial application. It is solely an object of scientific research in the fields of mineralogy, crystal chemistry, and the geochemistry of rare-earth element deposits.

Properties

Crystal system: Tetragonal

Diagnostic features

## Identification Identifying the mineral in the field or based on macroscopic features is impossible. Definitive identification requires advanced analytical methods, such as X-ray diffraction (XRD) and micro-area chemical analysis (e.g., EDS/WDS spectrometry using a scanning electron microscope). ## Distinction from similar minerals It requires differentiation from other rare niobates and rare-earth minerals occurring in the Bayan Obo deposit. Differences are based solely on exact chemical composition and crystal structure parameters. ## Crystal habits Forms microscopic grains and inclusions in the host rock.

Geological environment

## Origin This mineral forms under specific geological conditions associated with the formation of unique, multi-element deposits of rare-earth metals, niobium, and iron. ## Mineral associations It occurs in paragenesis with other rare minerals of niobium and rare-earth elements that are characteristic of the Bayan Obo deposit. ## Localities The only confirmed occurrence (type locality) is the East Mine within the Bayan Obo deposit (Baotou Prefecture, Inner Mongolia, China).

Rarity

Extremely rare

For collectors

## Quality criteria In the case of such rare minerals, specimen value is primarily determined by analytical confirmation of its presence on the matrix. Specimens are solely of scientific and systematic interest, and their visual appeal is secondary. ## Notable localities The only source of specimens is the type locality at the East Mine (Bayan Obo) in China.

Care and storage

## Cleaning Specimens with this mineral should be cleaned exclusively using a gentle stream of compressed air. Mechanical cleaning with brushes, which could damage or remove microscopic crystals from the matrix, should be avoided. ## What to avoid Contact with acids, strong chemicals, and the use of ultrasonic cleaners must be strictly avoided, as these can lead to the chipping of fine grains. ## Storage Specimens should be stored in closed micromount boxes, protecting them from dust, moisture, and accidental mechanical damage.

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External references

https://www.mindat.org/min-499606.html