Alnaperbøeite-(Ce)
Chemical formula: (CaCe<sup>3+</sup><sub>2.5</sub>Na<sub>0.5</sub>)Al<sub>4</sub>(Si<sub>2</sub>O<sub>7</sub>)(SiO<sub>4</sub>)<sub>3</sub>O(OH)<sub>2</sub>
A very rare mineral from the gatelite group, a complex cerium, calcium, and sodium aluminosilicate, known from only one locality worldwide.
Description
## 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.
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
Collector aspects
## 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.