Kokinosite

Chemical formula: Na₂Ca₂[V⁵⁺₁₀O₂₈]·24H₂O

Kokinosite is a very rare, hydrated sodium calcium vanadate, forming brittle, orange crystals and coatings.

## Characteristics Kokinosite is a very rare mineral from the decavanadate group, belonging to the pascoite family. It forms aggregates of small, tabular or bladed crystals, and also occurs as earthy coatings and crusts on host rocks. Typical specimens have an intense, yellow-orange to brownish-orange color. ## Physical Properties This mineral is extremely soft, with a hardness of only 1.5 on the Mohs scale, meaning it can be scratched with a fingernail. It is very brittle. Its density is approximately 2.35 g/cm³. Crystals exhibit a vitreous luster and are transparent. ## Colors and Varieties Kokinosite occurs in shades from yellow-orange to orange-brown. No distinct varieties have been identified. ## History and Name The mineral's name honors Kokino, an ancient megalithic astronomical observatory in North Macedonia. It was formally described and approved as a new mineral species by the International Mineralogical Association (IMA) in 2019. The type locality (locus typicus) is the Saint Jude mine in the Slick Rock district, Colorado, USA. ## Uses Due to its extreme rarity, small crystal size, and fragility, kokinosite has no industrial applications. It is solely an object of interest for collectors specializing in rare minerals, particularly vanadates.

Properties

Mohs hardness
1.5
Luster
Vitreous
Streak
Yellow
Density
2.353
Cleavage
cleavage good on <mi>{01_1}</mi>
Fracture
Irregular/Uneven
Transparency
Transparent
Crystal system
Triclinic

Diagnostic features

## Identification Kokinosite can be identified by its characteristic yellow-orange color, very low hardness (1.5 on the Mohs scale), and occurrence as small, tabular crystals or coatings on sedimentary rocks. A yellow streak is also an auxiliary feature. ## Distinguishing from Similar Minerals It can be confused with other secondary vanadium minerals, such as pascoite or hewettite. Pascoite has a similar color but crystallizes in the monoclinic system and has a slightly different chemical composition. Precise differentiation of these minerals often requires advanced chemical (EDS) or X-ray (XRD) analyses. ## Crystal Forms Kokinosite crystals are very small, usually not exceeding 1 mm. They take the form of thin, flattened tablets or blades. They often form radial aggregates, rosettes, or occur as earthy, powdery coatings.

Geological environment

## Genesis Kokinosite is a secondary mineral, formed in the oxidation zone of uranium-vanadium deposits located in sedimentary rocks, mainly sandstones. It forms as a result of the weathering of primary vanadium minerals in an arid climate. ## Mineral Associations This mineral co-occurs with other secondary vanadates, such as sherwoodite, pascoite, hewettite, as well as with montmorillonite, quartz, and calcite. ## Localities The only confirmed and described occurrence of kokinosite in the world is its type locality - the Saint Jude mine in the Slick Rock mining district, San Miguel County, Colorado, USA.

Rarity

Extremely rare

For collectors

## Quality Criteria The most desirable specimens are those with well-formed, sharp crystals forming aesthetic, radial aggregates on a contrasting rock matrix. The intensity and saturation of the orange color also increase the specimen's value. Due to the microscopic size of the crystals, specimens are primarily evaluated under magnification. ## Popular Localities The only source of kokinosite specimens is the Saint Jude mine in Colorado, USA. All samples available on the collector's market originate from this single locality.

Care and storage

## Cleaning Kokinosite specimens are extremely delicate and sensitive to water. They should not be wet cleaned. Only very careful dust removal with a soft brush or a stream of compressed air from a distance is permissible. ## What to Avoid Contact with water, which can dissolve or damage the mineral, must be strictly avoided. It should be protected from all chemicals, high temperatures, and direct sunlight, which can cause dehydration and color change. Due to its low hardness, it is extremely susceptible to mechanical damage. ## Storage Specimens should be stored in stable conditions, in a dry environment, preferably in a sealed, closable "micromount" box away from light and heat sources. Protect from vibrations and impacts.

External references

Sources

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