Amableite-(Ce)

Chemical formula: Na15[(Ce3+1.5Na1.5)Mn2+3]Mn2+2Zr4+3☐Si[Si24O69(OH)3](OH)2·H2O

Amableite-(Ce) is an extremely rare mineral from the eudialyte supergroup, forming colorless or pale yellow, tabular crystals.

Description

## Characteristics Amableite-(Ce) is a very complex silicate of sodium, cerium, manganese, and zirconium, belonging to the eudialyte supergroup. It occurs as small aggregates, usually not exceeding 0.5 mm. It forms thin, tabular crystals that often arrange into rosette-like clusters. Its appearance is subtle, and specimens are typically colorless or take on a pale yellow hue. ## Physical Properties This mineral is characterized by a vitreous luster and is transparent. Its density, calculated based on chemical composition and crystal structure, is 2.95 g/cm³. Hardness has not yet been determined. ## Colors and Varieties The observed colors are colorless and pale yellow. Due to its recent discovery and extreme rarity, no color varieties or commercial forms are known. ## History and Name Amableite-(Ce) was officially recognized as a new mineral species by the International Mineralogical Association (IMA) in 2021 (IMA2021-024). Its name honors Joseph-Amable-Désir Lefranc (1930–2019), a Canadian mineral collector renowned for his intensive searches at the mineral's type locality – Mont Saint-Hilaire. The suffix "-(Ce)" indicates that cerium is the dominant rare-earth element in its structure. ## Applications As a microscopic and extremely rare mineral, amableite-(Ce) has no industrial applications. Its significance is purely scientific and for collectors, being an object of interest for specialized micromineral collectors.

Diagnostic features

## Identification Identifying amableite-(Ce) based on visual characteristics is practically impossible and requires advanced analytical techniques, such as energy-dispersive spectroscopy (EDS) or wavelength-dispersive spectroscopy (WDS) to confirm its unique chemical composition. The key is to confirm the presence of sodium, cerium, manganese, and zirconium in appropriate proportions. ## Distinguishing from Similar Minerals This mineral can be confused with many other colorless or pale yellow, rare silicates found at Mont Saint-Hilaire, such as catapleiite, elpidite, or other members of the eudialyte supergroup. Definitive distinction is only possible through chemical analysis. ## Crystal Forms Amableite-(Ce) forms hexagonal, tabular crystals. They most often occur as aggregates and small, radial clusters resembling rosettes.

Geological environment

## Genesis Amableite-(Ce) forms in a unique geological environment, specifically in pegmatite dikes associated with nepheline syenite intrusions. It is a mineral of the late stage of crystallization under conditions of high activity of rare and volatile elements. ## Mineral Associations This mineral occurs in association with other rare minerals typical of Mont Saint-Hilaire. Its main associations include: aegirine, albite, microcline, catapleiite, elpidite, eudialyte, lorenzenite, polylithionite, and serandite. ## Localities The only confirmed occurrence of amableite-(Ce) in the world is its type locality: the Poudrette quarry at Mont Saint-Hilaire, in the Montérégie region, Quebec, Canada. This is one of the most famous mineralogical localities worldwide.

Rarity

Extremely rare

Collector aspects

## Quality Criteria For micromineral collectors, the value of an amableite-(Ce) specimen depends on several factors. The most important are well-formed crystals, creating distinct tablets or aesthetic rosettes. Specimens with minimal damage, good transparency, and those that contrast with the rock matrix are highly valued. The size of aggregates, although always small, also matters – larger clusters are more desirable. The presence of interesting associated minerals can further increase the specimen's value. ## Popular Localities As this mineral is known exclusively from one location, all available specimens come from the Poudrette quarry at Mont Saint-Hilaire, Canada. This locality is the source of the most prized specimens of this mineral.

Care and storage

## Cleaning Due to the microscopic size and potential fragility of the crystals, mechanical or chemical cleaning is not recommended. Specimens should be protected from dust. If necessary, a gentle stream of air from a photographic blower can be used. ## What to Avoid Ultrasonic cleaners, all chemical solvents, acids, and sudden temperature changes should be absolutely avoided. The crystals are likely very delicate and susceptible to mechanical damage. ## Storage The safest storage method is to place the specimen in a "micromount" box, which protects it from dust, shocks, and damage. Avoid exposure to direct sunlight, although there is no data on its effect on the mineral.