Coskrenite-(Ce)

Chemical formula: Ce³⁺₂(S⁶⁺O₄)₂((C₂)⁶⁺O₄)·8H₂O

Coskrenite-(Ce) is a very rare, hydrated cerium sulfate-oxalate, forming tiny, transparent crystals with a vitreous luster.

## Characteristics Coskrenite-(Ce) is a mineral from the sulfate and oxalate group. It occurs as very small, bladed or tabular crystals, rarely exceeding 1 mm in length. They are transparent and characterized by a vitreous luster. Due to its extreme rarity and small crystal size, it is a mineral of purely scientific and collector's interest. ## Physical Properties Crystals exhibit a vitreous luster and are transparent. Hardness and density have not been precisely determined due to the lack of sufficient material for research. The streak of the mineral is white. ## Colors and Varieties Typical specimens range in color from creamy to pale pink, especially under incandescent light. No varieties of this mineral have been distinguished. ## History and Name The mineral was named in honor of T. Dennis Coskren (born 1943), an American geologist and researcher of secondary minerals. The -(Ce) suffix in the name indicates the dominance of cerium as a rare earth element in its chemical composition. It was approved as a new mineral species by the International Mineralogical Association (IMA) in 1996. The type locality (locus typicus) is Alum Cave Bluff in Sevier County, Tennessee, USA. ## Uses Coskrenite-(Ce) has no industrial applications. It is an object of interest for specialized collectors of rare minerals and scientists studying the mineralogy of rare earth elements.

Properties

Luster
Vitreous
Streak
White
Density
0
Cleavage
{001}
Transparency
Transparent
Crystal system
Triclinic

Diagnostic features

## Identification Identification of coskrenite-(Ce) under amateur conditions is practically impossible. It requires advanced analytical methods, such as X-ray diffraction (XRD) and chemical microanalysis (EDS/WDS) to confirm its composition and crystal structure. Visually, it is simply a microscopic, transparent mineral with a vitreous luster. ## Distinguishing from Similar Minerals It can be confused with many other secondary sulfates or oxalates found in similar parageneses, such as gypsum, epsomite, or whewellite. Definitive differentiation is only possible through specialized laboratory tests. ## Crystal Forms It forms very small, elongated, bladed or tabular crystals, often grouped into small aggregates. Crystals rarely reach 1 mm in length.

Geological environment

## Genesis Coskrenite-(Ce) is a secondary mineral, formed as a result of weathering processes of rocks rich in sulfides (mainly pyrite) and rare earth element minerals. It forms as a product of the reaction of acidic mine waters with organic matter (e.g., plant remains) within alum shales. ## Mineral Associations At its type locality, it co-occurs with epsomite, alunogen, potash alum, tschermigite, gypsum, melanterite, pickeringite, apjohnite, halotrichite, and rozenite. ## Localities The only confirmed occurrence of coskrenite-(Ce) in the world is its type locality: Alum Cave Bluff, in Great Smoky Mountains National Park, Sevier County, Tennessee, USA.

Rarity

Extremely rare

For collectors

## Quality Criteria The quality of a coskrenite-(Ce) specimen is primarily assessed based on the presence of well-formed, albeit microscopic, crystals that can be identified under magnification. Due to its extreme rarity, any analytically confirmed specimen is valuable. Contrast with the surrounding matrix also enhances its visual appeal. ## Popular Localities The only source of specimens is the type locality in Tennessee, USA. Mineral collecting within Great Smoky Mountains National Park is strictly prohibited, making new specimens virtually unavailable on the market. All existing samples in collections originate from old collections, acquired before the park's establishment or under special research permits.

Care and storage

## Cleaning Due to the extreme delicacy and small size of the crystals, mechanical cleaning is highly inadvisable. If absolutely necessary, compressed air can be used from a safe distance to remove loose dust particles. Avoid contact with water and any chemicals. ## What to Avoid Strictly avoid contact with water, acids, detergents, and other chemicals that may dissolve or damage the mineral. The crystals are very brittle and sensitive to shocks and temperature changes. Do not expose the specimen to direct sunlight. ## Storage Coskrenite-(Ce) specimens should only be stored in specialized, sealed "micromount" boxes that protect them from dust, moisture, and mechanical damage. It is best to keep them in stable room conditions, away from heat and light sources.

External references

Sources

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