Cerite-(CeCa)

Chemical formula: (Ce³⁺₇Ca₂)&#₉₇₂₃;Mg(SiO₄)₃(SiO₃OH)₄(OH)₃

A rare cerium and calcium silicate, occurring in massive aggregates with a characteristic clove-brown color.

## Characteristics Cerite-(CeCa) is a complex silicate from the cerite group, primarily containing cerium and calcium. It rarely forms distinct crystals, most often occurring as granular or massive aggregates. Its appearance is usually inconspicuous, and specimens typically have a clove-brown color with a reddish tint. In thin fragments, it can be significantly lighter, from pale lilac to almost colorless. ## Physical Properties This mineral is characterized by a hardness of 5.5 on the Mohs scale, placing it in the same category as apatite. It has a relatively high density, approximately 4.75 g/cm³, which is palpable in hand even for small specimens. The luster is most often resinous or greasy. It is a brittle mineral with an uneven, irregular fracture. ## Colors and Varieties The dominant color of cerite-(CeCa) is clove-brown, often with a reddish or grayish tint. In thin fragments or at the edges of aggregates, its color lightens to pale lilac, grayish-brown, or even becomes colorless. No named color varieties or commercial varieties are distinguished. ## History and Name The name "cerite" comes from the discovery of the element cerium, which was first identified in a mineral from the Bastnäs mine in Sweden. The element's name refers to the then newly discovered dwarf planet Ceres. The suffix "-(CeCa)" was added to precisely define the chemical composition of this particular mineral variety, indicating the dominance of cerium and calcium in specific positions within its crystal structure. The type locality (locus typicus) is the St Görans mine in the Bastnäs mining complex in Riddarhyttan, Sweden. ## Uses Cerite-(CeCa), like other cerite minerals, was historically an ore of rare earth elements, mainly cerium. Currently, due to its rarity and occurrence in small quantities, it has no industrial significance. It is solely an object of interest for collectors specializing in rare minerals and rare earth element minerals.

Properties

Mohs hardness: 5.5
Luster: Resinous
Streak: Grayish white
Density: 4.75
Fracture: Irregular/Uneven
Transparency: Translucent,Opaque
Crystal system: Trigonal

Diagnostic features

## Identification Cerite-(CeCa) is primarily identified by its characteristic clove-brown color, resinous luster, and massive, granular form. Its relatively high density is also a helpful diagnostic feature. A grayish-white streak distinguishes it from many other brown minerals. ## Distinguishing from Similar Minerals It can be confused with other rare earth element minerals, such as allanite or monazite, which often occur in similar environments. Differentiation usually requires advanced analytical methods (e.g., EDS), although allanite is often black and has a more vitreous luster. It is distinguished from eudialyte by the absence of a characteristic pink color and a different occurrence environment. ## Crystal Forms Well-formed crystals are extremely rare. It typically forms massive, granular, or cryptocrystalline aggregates, often embedded in the host rock.

Geological environment

## Genesis Cerite-(CeCa) is a mineral of metamorphic and magmatic origin. It forms in skarns and pegmatites rich in rare earth elements. At its type locality in Bastnäs, it occurs in magnesian skarns that have been modified by hydrothermal processes. ## Mineral Associations This mineral often co-occurs with other rare earth element minerals. In Bastnäs, its typical associated minerals include cerite-(Ce), allanite-(Ce), bastnäsite-(Ce), ferriallanite-(Ce), törnebohmite-(Ce), as well as chalcopyrite, molybdenite, and fluorite. ## Localities The most important and historical occurrence of cerite-(CeCa) is its type locality - the Bastnäs mines in Riddarhyttan, Västmanland region, Sweden. This is a classic locality for many rare earth element minerals. Beyond Sweden, its presence has been noted in several other places worldwide, but these occurrences are of much lesser significance.

Rarity

Very rare

For collectors

## Quality Criteria The most valued by collectors are specimens rich in cerite-(CeCa), exhibiting an intense, clove-brown color. Since well-formed crystals practically do not exist, the quality of a specimen is assessed based on the richness of the aggregate and its purity. Co-occurrence with other, colorfully contrasting minerals from this locality adds to its attractiveness. ## Popular Localities The only source of specimens of collector's significance are the historical Bastnäs mines in Sweden. Material from this locality is considered classic and most desirable.

Care and storage

## Cleaning Cerite-(CeCa) specimens should be cleaned very carefully. It is safest to use a soft brush to remove dust. If necessary, compressed air can be used. Contact with water, especially tap water containing chlorine, is not recommended. ## What to Avoid Avoid contact with all chemicals, including acids and strong bases, which can damage the mineral's surface. The mineral is brittle, so it should be protected from impacts and falls. It should not be heated or subjected to sudden temperature changes. ## Storage Cerite-(CeCa) specimens are best stored in separate, padded display boxes to prevent scratching by harder minerals. It does not require special conditions regarding light or humidity, but standard room conditions are recommended.

External references

https://www.mindat.org/min-931.html