Chinleite-(Ce)

Chemical formula: NaCe³⁺(S⁶⁺O₄)₂(H₂O)

Chinleite-(Ce) is a rare, hydrated sodium and cerium sulfate, forming colorless, platy crystals with a vitreous luster.

## Characteristics Chinleite-(Ce) is a hydrated sodium and cerium sulfate, belonging to the group of rare minerals. It occurs as small, hexagonal or trigonal crystals with a platy habit, often forming rosette-like aggregates. It is a secondary mineral, formed in the oxidation zones of uranium-vanadium deposits. Specimens are usually colorless and transparent, which, combined with the small size of the crystals, makes them difficult to observe in the field. ## Physical Properties This mineral is characterized by a relatively low hardness of 2.5-3 on the Mohs scale, meaning it is quite soft and susceptible to scratching. Its density, calculated from crystallographic data, is approximately 3.15 g/cm³. The crystals exhibit a vitreous luster. It is a brittle mineral with a splintery fracture. ## Colors and Varieties Chinleite-(Ce) is typically colorless. No colored varieties or trade names have been distinguished. ## History and Name The mineral's name refers to the Chinle Formation, a group of Late Triassic sedimentary rocks where it was first identified. The -(Ce) suffix in the name indicates the dominant rare earth element in its chemical composition – cerium. The mineral was first described in 1998 by J.E. Taggart, Jr., E.E. Foord, A.C. Roberts, and T.A. Moffatt based on specimens found in the Blue Streak Mine in Montrose County, Colorado, USA. ## Uses Due to its extreme rarity and small crystal size, Chinleite-(Ce) has no industrial applications. It is of purely scientific interest and is sought after by specialized collectors of rare minerals.

Properties

Mohs hardness
2.5-3
Luster
Vitreous
Streak
white
Density
3.149
Cleavage
one good cleavage (probably on {100})
Fracture
Splintery
Transparency
Transparent
Crystal system
Trigonal

Diagnostic features

## Identification Chinleite-(Ce) is difficult to identify visually. It is recognized by its characteristic small, colorless, hexagonal, platy crystals, often forming rosette-like aggregates. It occurs in a specific geological environment – on sandstones in the oxidation zones of uranium-vanadium deposits. Final identification requires advanced analytical methods, such as X-ray diffraction (XRD) and chemical analysis (EDS). ## Distinguishing from Similar Minerals It can be confused with other secondary sulfates, such as gypsum or celestine, but differs from them in crystal habit and significantly smaller size. Co-occurring natrojarosite usually has a yellowish color. Key for differentiation are the environment of occurrence and mineral paragenesis. ## Crystal Forms It forms thin, platy crystals with a hexagonal or trigonal outline. These crystals often combine into small, rosette-like or radial aggregates.

Geological environment

## Genesis It is a secondary mineral that crystallizes as a result of weathering and oxidation processes of primary ore minerals (mainly uraninite) under low temperature and pressure conditions. It forms in voids and on fracture surfaces in sedimentary rocks, most commonly sandstones, within "roll-front" type uranium and vanadium deposits. ## Mineral Associations Chinleite-(Ce) co-occurs with other secondary minerals of the oxidation zone. It is most commonly associated with: natrojarosite, celestine, barite, anglesite, carniomarkite, as well as iron oxides (hematite, goethite) and clay minerals. ## Localities The most important and type locality for this mineral is the Blue Streak Mine in Bull Canyon, Montrose County, Colorado, USA. This is the only confirmed and well-documented locality in the world from which Chinleite-(Ce) specimens originate.

Rarity

Very rare

For collectors

## Quality Criteria The quality of Chinleite-(Ce) specimens is primarily assessed based on the abundance and development of crystals on the rock matrix. Most valued are samples with numerous, well-formed, transparent crystals forming aesthetically pleasing, rosette-like aggregates. Due to the mineral's colorless nature, contrast with a colored matrix (e.g., sandstone) enhances the specimen's attractiveness. Crystal size is also important, although they rarely exceed fractions of a millimeter. ## Popular Localities The only source of collector specimens is the type locality – the Blue Streak Mine in Colorado, USA. All samples available on the collector's market originate from this single location.

Care and storage

## Cleaning Specimens should be cleaned with utmost care, using only compressed air to remove dust. Due to its water solubility, contact with water and other liquids must be strictly avoided. Mechanical cleaning is not recommended due to its low hardness and brittleness. ## What to Avoid Avoid contact with water and chemical solutions, which can damage or dissolve the mineral. Its low hardness makes it very susceptible to scratching, so it should be protected from contact with harder minerals. Vibrations and impacts should also be avoided. ## Storage It is recommended to store specimens in sealed, airtight "micromount" containers that protect against dust, moisture, and mechanical damage. Display should be in stable conditions, away from sources of moisture and sudden temperature changes.

External references

Sources

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