Longshoushanite-(Ce)

Chemical formula: Ce₃+₄MgAl₂Ti₄+₂(Si₂O₇)₂O₈

An extremely rare chevkinite-group silicate, discovered in 2023 in the Longshoushan uranium ore zone in China, rich in cerium, magnesium, aluminum, and titanium.

## Characteristics Longshoushanite-(Ce) is an extremely rare silicate mineral belonging to the complex chevkinite group. Chemically, it is a cerium, magnesium, aluminum, and titanium silicate. As a newly discovered mineral, it typically occurs as microscopic crystals or small inclusions in other minerals, which is typical for many rare accessory phases rich in rare earth elements. Due to its size, it does not form impressive macroscopic specimens. ## Physical properties Due to its recent discovery and the microscopic size of the crystals found, detailed physical properties of macroscopic specimens have not yet been extensively described in the literature. The mineral crystallizes in the monoclinic system. Like other minerals of the chevkinite group, it is characterized by a complex crystal structure that can undergo partial metamictization under the influence of radiation from adjacent uranium minerals. ## Colors and varieties Minerals of the chevkinite group typically assume dark colors, ranging from dark brown to completely black. The exact color of pure longshoushanite-(Ce) depends on the presence of trace element impurities and the degree of potential crystal structure damage (metamictization). No varieties of this mineral are known. ## History and name The mineral was officially approved by the International Mineralogical Association (IMA) in 2023 under the number IMA 2023-074. Its name comes directly from the type locality - the Longshoushan uranium ore zone, located in the Jinchuan District (Jinchang) of Gansu Province, China, where it was first identified. The suffix "-(Ce)" was added in accordance with the Levinson rule, indicating cerium as the dominant rare earth element in the corresponding structural position of the mineral.

Properties

Crystal system: Monoclinic

Diagnostic features

## Identification Macroscopic identification of longshoushanite-(Ce) in the field or in a collection is impossible. Identification requires advanced analytical techniques, such as electron probe microanalysis (EPMA) to determine the exact chemical composition and X-ray diffraction (XRD) to confirm the crystal structure. ## Distinguishing from similar minerals Distinguishing this mineral from other members of the chevkinite group (such as chevkinite-(Ce) or perrierite-(Ce)) relies exclusively on precise chemical analysis. Demonstrating the dominance of magnesium and aluminum in the corresponding structural positions of the crystal lattice is key. ## Crystal habits The mineral forms microscopic crystals in the monoclinic system. It is most commonly found as fine grains or inclusions inside other rock-forming and ore minerals.

Geological environment

## Origin Longshoushanite-(Ce) forms under specific geological conditions associated with hydrothermal or metasomatic processes. It crystallizes in environments enriched in rare earth elements (REE), titanium, and uranium. ## Mineral associations Given its discovery site, the mineral occurs in zones mineralized with uranium ores. It co-occurs with other rare mineral phases containing rare earth elements and uranyl minerals typical of this deposit. ## Localities The only confirmed occurrence of this mineral (the type locality) is the Longshoushan uranium ore zone, located in Jinchuan District, Jinchang, Gansu Province, China.

Rarity

Extremely rare

For collectors

## Quality criteria This mineral does not occur in the form of classic, aesthetic collector specimens. Its value relies exclusively on its extreme systematic rarity. For rarity collectors and systematic collectors, the most important criterion is confirmed origin from the type locality and the presence of the mineral verified by analytical research. ## Notable localities The world's only source of specimens is the type locality in China (the Longshoushan uranium ore zone).

Care and storage

## Cleaning Due to its microscopic size and occurrence as inclusions in the host rock, specimens are not subject to standard cleaning. Mechanical methods and ultrasonic cleaners, which could irreversibly damage the delicate material, must be strictly avoided. ## What to avoid Contact with any chemicals, including strong acids and bases that can etch silicates and co-occurring minerals in the rock, should be avoided. ## Storage Specimens should be stored in a dry environment, preferably in standard micromount boxes, protecting them from dust and mechanical damage. Because the mineral originates from a uranium ore zone, the host rock may exhibit elevated background radiation - standard precautions for radioactive minerals should be observed.

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External references

https://www.mindat.org/min-499371.html