Shakhdaraite-(Y)

Chemical formula: ScYNb₅+₂O₈

Shakhdaraite-(Y) is an extremely rare scandium, yttrium, and niobium oxide, found in granitic pegmatites in Tajikistan.

## Characteristics Shakhdaraite-(Y) is a very rare mineral from the oxide group, chemically classified as a scandium and yttrium niobate. It occurs as very small, irregular (anhedral) grains, rarely forming poorly developed, prismatic crystals not exceeding 0.3 mm in size. Its grains are most often intergrown with other minerals, mainly albite. It is opaque and black in color. ## Physical Properties The mineral's hardness on the Mohs scale is approximately 6. It exhibits a submetallic luster and an uneven fracture. The density calculated based on the chemical formula and unit cell parameters is 5.53 g/cm³. It shows neither cleavage nor fluorescence under ultraviolet light. ## Colors and Varieties The mineral is uniformly black. Due to its extreme rarity and microscopic occurrence, no color varieties or commercial forms are distinguished. ## History and Name Shakhdaraite-(Y) was officially recognized by the International Mineralogical Association (IMA) in 2011. Its name comes from its discovery locality – the Shakhdara River valley in the Gorno-Badakhshan region of Tajikistan. The suffix -(Y) in the name (the so-called Levinson modifier) indicates that yttrium is the dominant rare earth element in its structure. The mineral was described by a team of mineralogists, including L.A. Pautov and A.A. Agakhanov. ## Applications Due to its extreme rarity and occurrence only as microscopic grains, shakhdaraite-(Y) has no commercial or industrial applications. It is solely an object of scientific research and a valuable acquisition for specialized collectors of microminerals.

Properties

Mohs hardness: 6
Luster: Sub-metallic
Streak: Brown
Density: 5.53
Cleavage: None
Fracture: Uneven
Transparency: Opaque
Crystal system: Monoclinic

Diagnostic features

## Identification Identification of shakhdaraite-(Y) based on visual characteristics is impossible. The mineral occurs as fine, black grains embedded in the rock. Positive identification requires advanced analytical techniques, such as X-ray microanalysis (EDS/WDS) in a scanning electron microscope (SEM), to confirm its unique chemical composition, rich in scandium, yttrium, and niobium. ## Differentiation from Similar Minerals Shakhdaraite-(Y) can be confused with other black, heavy oxide minerals, such as fergusonite, euxenite, or samarskite, which often occur in similar pegmatitic environments. The key distinguishing feature of shakhdaraite-(Y) is its unique chemical signature, especially its high scandium content, which is usually trace or absent in the aforementioned minerals. ## Crystal Forms The mineral primarily forms irregular, anhedral grains ranging from 10 to 200 micrometers in size. Very rarely, poorly developed, short, prismatic crystals are observed.

Geological environment

## Genesis Shakhdaraite-(Y) is a magmatic mineral, crystallizing in the late stage of evolution of granitic pegmatites, rich in rare earth elements (REE), niobium, and scandium. ## Mineral Associations This mineral occurs in close association with other pegmatitic minerals. At its type locality, it was found in association with albite (cleavelandite variety), quartz, mica (muscovite), potassium feldspars, as well as rarer minerals such as milarite, bazzite, beryl, euxenite-(Y), and fergusonite-(Y). ## Localities The only confirmed occurrence of shakhdaraite-(Y) in the world is its type locality: the Dara-i-Pioz pegmatite in the Shakhdara River valley, in the Alay Range, Gorno-Badakhshan region of Tajikistan. This is a famous mineralogical site known for the occurrence of many unique and rare minerals.

Rarity

Extremely rare

For collectors

## Quality Criteria For such a rare mineral, the primary criterion of value is its mere presence and the ability to confirm its diagnosis. Collector's specimens are usually fragments of the parent rock (matrix) with shakhdaraite-(Y) grains visible under a microscope. Specimens with more numerous, larger grains or accompanied by other rare associated minerals are more highly valued. Finding even a poorly formed crystal significantly increases the scientific and collector's value of the specimen. ## Popular Localities The only source of shakhdaraite-(Y) specimens is its type locality in Tajikistan. Material from this location is extremely difficult to obtain and appears on the collector's market sporadically, mainly through specialized dealers and micromineral collectors.

Care and storage

## Cleaning Specimens containing shakhdaraite-(Y) should be cleaned very carefully, preferably using compressed air to remove dust. For heavier soiling, a soft brush and distilled water can be used, followed by thorough drying of the specimen. Due to the microscopic nature of the grains, mechanical cleaning is highly risky. ## What to Avoid Ultrasonic cleaners should be absolutely avoided, as they can cause delicate grains to chip out of the rock matrix. Contact with acids and strong chemicals should be avoided. The mineral should be protected from sudden temperature changes. ## Storage Shakhdaraite-(Y) specimens are typically micromounts. The safest way to store them is in dedicated, enclosed "micromount" boxes, with a label containing the exact locality. This protects the specimen from dust, moisture, and mechanical damage.

Sources

IMA Mineral List (CNMNC)