Yttrotungstite-(Y)

Chemical formula: Y(W<sup>6+</sup>,Fe<sup>3+</sup>,Si,Al,Ti<sup>4+</sup>)<sub>2</sub>(O,OH,H<sub>2</sub>O)<sub>9</sub>

Itrorotungstite-(Y) is a rare, secondary tungsten and yttrium mineral, forming microscopic, yellow to brown crystals and coatings.

## Characteristics Itrorotungstite-(Y) is a secondary mineral, forming in the oxidation zones of tungsten deposits. It occurs as very small, tabular or bladed crystals, rarely exceeding 0.5 mm in length. Most often, it forms earthy or powdery aggregates, coatings, and crusts on other minerals, especially on ferberite and scheelite. Its color ranges from canary yellow, through yellowish-brown, to brown. ## Physical Properties Itrorotungstite-(Y) crystals exhibit a luster described as adamantine to resinous, while its earthy aggregates are dull. It is a translucent to opaque mineral. Due to the microscopic size of its crystals, its physical properties, such as hardness, are difficult to measure precisely. The density calculated based on its chemical formula and unit cell parameters is approximately 6.35 g/cm³. ## Colors and Varieties This mineral does not have named varieties. Its coloration is uniform and includes shades of yellow and brown, from canary yellow to dark brown. The color is a characteristic feature, related to its chemical composition. ## History and Name Itrorotungstite-(Y) was first described in 1927 by A. Scrivenor based on material from the Kramat Pulai mine in Perak, Malaysia. The name refers to its chemical composition – the dominance of yttrium (Y) and tungsten (W). The suffix -(Y) was added in 1987 by the International Mineralogical Association (IMA) to formally indicate yttrium as the dominant rare-earth element in this mineral, in accordance with current naming conventions.

Properties

Mohs hardness
1
Luster
Adamantine
Streak
Yellow
Density
6.35
Cleavage
Perfect on {010}
Fracture
Uneven
Transparency
Translucent to opaque
Crystal system
Monoclinic

Diagnostic features

## Identification Itrorotungstite-(Y) is identified by its characteristic canary yellow to brown color, earthy or powdery appearance, and occurrence as an oxidation product of tungsten minerals. Due to the microscopic size of its crystals, definitive 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 yellow-colored secondary tungsten minerals, such as tungstite (WO₃·H₂O) or ferritungstite. Tungstite is usually more purely yellow and has a different chemical composition (lacks yttrium). Reliable differentiation from these minerals is only possible through laboratory analysis. ## Crystal Forms It forms very small, thin, tabular crystals with a bladed habit, often grouped into rosette-like or radiating aggregates. Most often, however, it occurs in the form of earthy, dusty, or powdery coatings and masses.

Geological environment

## Genesis It is a secondary mineral, formed by the weathering and oxidation of primary tungsten minerals, such as wolframite (especially its iron-rich variety – ferberite) and scheelite. It forms in near-surface conditions, in the oxidized zones of hydrothermal and pegmatitic deposits containing tungsten. ## Mineral Associations It most commonly co-occurs with the minerals from which it forms, namely ferberite and scheelite. It is also accompanied by other secondary minerals such as tungstite, quartz, hematite, goethite, and various clay minerals. ## Localities The most important and classic locality, from which the type material originates, is the Kramat Pulai mine in Kinta, Perak, Malaysia. Other confirmed localities include the Hemerdon mine in Devon, England; the La Bellière mine in France; and some deposits in the Kiwira region in Tanzania.

Rarity

Very rare

For collectors

## Quality Criteria The collecting appeal of Itrorotungstite-(Y) specimens primarily depends on the intensity and saturation of the yellow color and the richness of the coating on the matrix. Since the crystals are microscopic, specimens with visible (under high magnification) crystalline aggregates or rosettes are much more valued than purely earthy coatings. Contrast with a dark matrix (e.g., ferberite) also enhances the visual appeal of the specimen. ## Popular Localities The most sought-after specimens by collectors come from the type locality in Kramat Pulai, Malaysia, which are historically most significant. Material from the English Hemerdon mine is also found in specialized collections.

Care and storage

## Cleaning Itrorotungstite-(Y) specimens are extremely delicate and usually occur as microscopic coatings. Mechanical or chemical cleaning is not recommended. If dust removal is necessary, use compressed air from a safe distance or a very soft brush, proceeding with utmost caution. ## What to Avoid Contact with water, acids, and other chemicals that may dissolve or damage this mineral should be strictly avoided. Earthy aggregates are brittle and susceptible to abrasion. Specimens should be protected from vibrations, shocks, and direct physical contact. ## Storage Specimens should be stored exclusively in stable, sealed "micromount" boxes to protect them from mechanical damage and dust. They do not require special conditions regarding light or humidity, however, standard collecting conditions (stable temperature and low humidity) are recommended.

Sources

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