Alnaperbøeite-(Ce)

Chemical formula: (CaCe₃+₂.₅Na₀.₅)Al₄(Si₂O₇)(SiO₄)₃O(OH)₂

A very rare mineral from the gatelite group, a complex cerium, calcium, and sodium aluminosilicate, known from only one locality worldwide.

## Characteristics Alnaperbøeite-(Ce) is a very rare, complex aluminosilicate belonging to the gatelite group. It occurs as irregular, anhedral grains, not exceeding 1 mm in size. This mineral is transparent and has a characteristic reddish-brown or brownish-red color. Due to its extreme rarity and microscopic form, it is primarily of scientific interest and sought after by specialized micromineral collectors. ## Physical Properties The Mohs hardness of alnaperbøeite-(Ce) is 6.5-7, placing it on par with quartz. It exhibits a vitreous luster. Its density, calculated based on chemical composition and unit cell parameters, is 4.54 g/cm³. ## Colors and Varieties This mineral occurs in a uniform reddish-brown to brownish-red coloration. No color varieties or commercial forms are known. ## History and Name Alnaperbøeite-(Ce) was officially recognized by the International Mineralogical Association (IMA) in 2019. Its name is tripartite: "Al" and "Na" come from aluminum and sodium, essential components of the mineral. The "perbøeite" part honors the Norwegian amateur mineralogist Per Bøe (1930–2017). The suffix "-(Ce)" indicates that cerium is the dominant rare-earth element in its structure. ## Uses Due to its extreme rarity and occurrence in microscopic quantities, alnaperbøeite-(Ce) has no industrial applications. It holds purely scientific and collector's significance.

Properties

Mohs hardness: 6.5-7
Luster: Vitreous
Streak: White
Density: 4.54
Cleavage: None
Transparency: Transparent
Crystal system: Monoclinic

Diagnostic features

## Identification Identification of alnaperbøeite-(Ce) is impossible based on visual characteristics alone. Due to its occurrence as small, anhedral grains, definitive identification requires advanced analytical techniques, such as X-ray microanalysis (EDS/WDS) to determine chemical composition and X-ray diffraction (XRD) to confirm crystal structure. ## Distinguishing from Similar Minerals In its natural environment, it may be confused with other reddish-brown minerals such as titanite, zircon, or allanite-(Ce), with which it co-occurs. Differentiation is only possible through laboratory analysis, which will reveal the unique chemical composition of alnaperbøeite-(Ce), particularly its high content of aluminum, cerium, and sodium. ## Crystal Forms This mineral forms only irregular, anhedral (lacking external crystal forms) grains up to 1 mm in size.

Geological environment

## Genesis Alnaperbøeite-(Ce) is a mineral formed under conditions of high-grade metamorphism. Its genesis is associated with the alteration of a calcite lens (marble) within gneisses. ## Mineral Associations This mineral occurs in association with other metamorphic minerals, such as phlogopite, zircon, titanite, allanite-(Ce), epidote, fluorapatite, and calcite. ## Localities The only confirmed locality of alnaperbøeite-(Ce) in the world is its type locality – the Bjørkåsen quarry in the municipality of Ofoten, Nordland county, Norway.

Rarity

Extremely rare

For collectors

## Quality Criteria As an extremely rare micromineral, the primary criterion for the value of any specimen is its unambiguous analytical identification. The most valuable samples are those where the alnaperbøeite-(Ce) grains are as large as possible (even if it's a fraction of a millimeter), clearly visible, and embedded in an aesthetic rock matrix, preferably accompanied by other rare minerals from this locality. ## Popular Localities The only source of specimens is the type locality in Bjørkåsen, Norway. Material from this location is extremely difficult to obtain and constitutes a rarity in specialized systematic and micromineral collections.

Care and storage

## Cleaning Specimens should be cleaned with utmost care, preferably using a soft brush or blown air to remove dust. Due to the microscopic size of the grains, avoid washing in water and mechanical cleaning, which could lead to material loss. ## What to Avoid Avoid contact with chemicals, especially strong acids. Ultrasonic cleaners are not recommended. As a mineral known from only one locality, every specimen is valuable and should be protected from any potentially harmful factors. ## Storage It is recommended to store specimens in specialized micromount boxes, which protect against dust, mechanical damage, and loss. Avoid exposure to extreme temperatures and humidity.

Sources

IMA Mineral List (CNMNC)