Taipingite-(CeCa)

Chemical formula: (Ce₃+₇Ca₂)&#₉₇₄₄;Mg(SiO₄)₃[SiO₃(OH)]₄F₃

Taipingite-(CeCa) is a very rare cerium and calcium silicate, distinguished by its complex composition and occurrence exclusively in one location worldwide.

## Characteristics Taipingite-(CeCa) is a mineral with a complex chemical structure, belonging to the silicate group. It occurs as irregular or partially formed grains, which can form small aggregates up to 1.5 mm in size. Its color ranges from brownish-red to brown. It is a translucent mineral with a vitreous luster. ## Physical Properties This mineral is characterized by a vitreous luster and is translucent. Its density, calculated based on composition and structure, is 4.835 g/cm³. The Mohs hardness has not yet been determined. ## Colors and Varieties Observed colors are brownish-red and brown. Due to its extreme rarity and recent discovery, no varieties of this mineral have been distinguished. ## History and Name Taipingite-(CeCa) was officially recognized as a new mineral by the International Mineralogical Association (IMA) in 2022 (IMA 2022-030). Its name comes from the nearby village of Taiping. The suffix -(CeCa) in the name, according to the rules for naming rare earth minerals, indicates the dominance of cerium (Ce) and calcium (Ca) in its structure. The type locality (locus typicus) is the Weishan rare earth metal deposit in China. ## Applications Due to its extreme rarity and occurrence as microscopic grains, taipingite-(CeCa) has no commercial or industrial applications. It is solely an object of scientific interest and a valuable acquisition for specialized collectors of systematic minerals.

Properties

Luster: Vitreous
Streak: Light brown
Density: 4.835
Cleavage: None
Transparency: Translucent
Crystal system: Trigonal

Diagnostic features

## Identification Visual identification of taipingite-(CeCa) is practically impossible. Its physical characteristics, such as brown color and occurrence as small grains, are non-specific. Reliable identification requires advanced analytical techniques, such as X-ray diffraction (XRD) and chemical analysis (e.g., EDS/WDS), which allow for the determination of its unique crystal structure and composition. ## Distinguishing from Similar Minerals It can be confused with other brown rare-earth-rich silicates found in similar geological environments. Final differentiation from minerals such as some varieties of allanite, gadolinite, or titanite is only possible based on laboratory analysis. ## Crystal Forms This mineral forms anhedral (irregular) to subhedral (partially formed) grains. Well-formed, euhedral crystals have not yet been observed.

Geological environment

## Genesis Taipingite-(CeCa) forms in a specific geological environment, namely pegmatite dikes enriched in aegirine and arfvedsonite. These pegmatites intrude into a syenite massif, indicating a genesis related to magmatic processes in an alkaline environment. ## Mineral Associations This mineral occurs in association with aegirine, arfvedsonite, fluorite, and minerals from the zircon group. Co-occurrence with these minerals is an important diagnostic clue at its discovery site. ## Localities The only confirmed occurrence of taipingite-(CeCa) in the world is its type locality – the Weishan rare earth metal deposit, in Weishan County, Jining Prefecture, Shandong Province, China.

Rarity

Extremely rare

For collectors

## Quality Criteria For such a rare mineral, occurring exclusively as microscopic grains, the primary criterion for value is its mere presence and identifiability. The most valuable specimens are those where the amount of taipingite-(CeCa) is relatively large, and its association with other minerals is clearly visible. Confirmation of the specimen's authenticity through scientific analysis is of key importance. Aesthetics are of secondary importance. ## Popular Localities The only source of specimens is the type locality in China. This mineral is not widely available on the collector's market and is mainly acquired by scientific institutions and highly specialized systematic collections.

Care and storage

## Cleaning Specimens should only be cleaned mechanically, using a soft brush to remove dust. If necessary, distilled water can be used. Ultrasonic cleaners should be avoided, as the internal properties of the mineral are not fully known. ## What to Avoid The mineral should be protected from contact with all chemicals, especially acids. Avoid sudden temperature changes. Prolonged exposure to intense sunlight is not recommended, as its effect on color stability has not been studied. ## Storage It is recommended to store specimens in stable conditions, in a sealed, padded "membrane box" to protect them from mechanical damage, dust, and moisture.

Sources

IMA Mineral List (CNMNC)