Saryarkite-(Y)

Chemical formula: Ca(Y,Th⁴⁺)Al₅(SiO₄)₂(PO₄)₂(OH)₇·6H₂O

Saryarkite-(Y) is a rare yttrium and calcium aluminosilicate-phosphate mineral, forming small, hexagonal crystals and radial aggregates.

## Characteristics Saryarkite-(Y) is a complex hydrated aluminosilicate and phosphate of calcium, yttrium, and thorium. It occurs as small, tabular or prismatic crystals with a hexagonal outline, which often form radial or stellate aggregates. Individual crystals rarely exceed 1-2 mm. It is a brittle mineral. ## Physical Properties The mineral is characterized by a Mohs hardness of 3.5-4 and a density of approximately 3.15 g/cm³. The luster is vitreous, and on fracture surfaces, it can be dull. It is transparent to translucent. ## Colors and Varieties Saryarkite-(Y) occurs in various shades of yellow – from light yellow and straw-yellow to yellowish-green. Colorless and white specimens have also been observed. No distinct varieties are recognized. ## History and Name The mineral's name comes from its discovery locality in the Saryarka (Сары-Арка) region of Kazakhstan, also known as the Kazakh Uplands. It was described and approved as a new mineral species in 1964 by E.I. Nefedov. The "-(Y)" suffix in the name indicates the dominance of yttrium in its chemical composition. ## Uses Due to its rarity and small crystal size, saryarkite-(Y) has no industrial applications. It is solely an object of interest for collectors specializing in rare minerals.

Properties

Mohs hardness
3.5-4
Color
White
Luster
Vitreous
Streak
White
Density
3.07
Cleavage
Perfect on {0001}
Fracture
Uneven
Transparency
Translucent
Crystal system
Tetragonal

Diagnostic features

## Identification Characteristic features of saryarkite-(Y) include its typical forms of occurrence as radial or stellate aggregates, composed of small, hexagonal crystals. The yellowish color, vitreous luster, and relatively low hardness are also helpful in identification. ## Distinguishing from Similar Minerals It can be confused with other rare secondary minerals of similar habit and color, such as some zeolites or other phosphates and silicates. Precise differentiation from minerals of the Dundasite group, such as kamotoite-(Y), requires advanced chemical (EDS) or X-ray (XRD) analyses due to visual similarity and similar occurrence environments. ## Crystal Forms It forms tabular or short-prismatic crystals with a hexagonal outline. It is most commonly found in the form of radial, spherulitic, or stellate aggregates and clusters, as well as thin coatings and crusts.

Geological environment

## Genesis Saryarkite-(Y) is a secondary mineral, forming in the oxidation (weathering) zones of polymetallic deposits, especially those containing fluorite, molybdenite, and rare earth minerals. It forms as a result of the alteration of primary minerals by surface waters. ## Mineral Associations It most commonly co-occurs with minerals such as fluorite, quartz, brochantite, chalcopyrite, galena, molybdenite, as well as rarer secondary minerals, including other yttrium minerals. ## Localities The most important and type locality, from which the best specimens originate, is the Kensu (or Kounrad) deposit in the Saryarka region of Kazakhstan. This is practically the only known locality where this mineral occurs in quantities and forms significant to collectors.

Rarity

Very rare

For collectors

## Quality Criteria The most prized specimens by collectors are those with well-formed, radial aggregates of intense yellow color, contrasting with the rock matrix (most often purple fluorite or quartz). The size of the aggregates and the absence of mechanical damage significantly increase the specimen's value. Due to the small size of the crystals, the aesthetics of the entire cluster is crucial. ## Popular Localities The only source of collectible specimens is the historical Kensu deposit in Kazakhstan. Specimens from this locality are considered classic and most desirable.

Care and storage

## Cleaning Specimens should be cleaned very carefully, using only a soft brush to remove dust. Due to its brittleness and potential reactivity, washing in water, and especially the use of any detergents or ultrasonics, should be avoided. ## What to Avoid The mineral is sensitive to acids. Contact with chemicals, sudden temperature changes, and mechanical shocks that could cause damage should be avoided. As a hydrated mineral, it may be sensitive to prolonged storage in overly dry environments. ## Storage It is recommended to store specimens in stable conditions, in closed display boxes, to protect them from dust, light, and mechanical damage. It is best to keep it away from other, harder minerals to prevent scratching.

External references

Sources

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