Yttrotungstite-(Nd)
Chemical formula: NdW<sup>6+</sup><sub>2</sub>O<sub>7</sub>(OH)·H<sub>2</sub>O
An extremely rare neodymium tungstate hydroxide, forming soft, earthy, yellow aggregates.
Description
## Characteristics Yttrotungstite-(Nd) is a mineral from the yttrotungstite group, in which neodymium is the dominant rare earth element. It is the neodymium analogue of yttrotungstite-(Y). It most often occurs as earthy, powdery, or dusty coatings and aggregates on other minerals. Rarely, it forms microscopic, lath-like crystals gathered in spherical aggregates. Its appearance is usually inconspicuous, and its significance is mainly scientific. ## Physical Properties This mineral is extremely soft, with a Mohs hardness of only 1-2, meaning it can be scratched with a fingernail. Nevertheless, due to the presence of heavy elements like tungsten and neodymium, it has a high calculated density of approximately 6.5 g/cm³. The luster is described as resinous to greasy. It is translucent to opaque. ## Colors and Varieties Yttrotungstite-(Nd) has a characteristic yellow, yellowish-brown, or brownish color. No distinct color varieties or commercial varieties are distinguished. It is part of an isomorphic series with other minerals from this group, such as yttrotungstite-(Y) and yttrotungstite-(Ce), from which it can only be distinguished by advanced chemical analyses. ## History and Name The mineral's name refers to its chemical composition – the originally identified "yttrotungstite" group (tungsten and yttrium) and the dominant rare earth element in this particular mineral, neodymium (Nd). As a distinct mineral species, it was approved by the International Mineralogical Association (IMA) in 2009. ## Applications Due to its extreme rarity and occurrence only in small aggregates, yttrotungstite-(Nd) has no industrial applications. It is solely an object of scientific interest and a valuable acquisition for specialized collectors of rare minerals.
Diagnostic features
## Identification Helpful identification features include: yellow color, very low hardness (1-2 on the Mohs scale), high density, resinous or greasy luster, and occurrence in the form of earthy coatings. Its characteristic environment of occurrence – oxidation zones of tungsten deposits – is also distinctive. ## Distinguishing from Similar Minerals Yttrotungstite-(Nd) can be confused with other secondary yellow tungsten minerals, such as tungstite, ferritungstite, or members of its own group (yttrotungstite-(Y), yttrotungstite-(Ce)). Definitive distinction is possible only through chemical analysis (e.g., EDS, WDS) to determine the dominant rare earth element. ## Crystal Forms This mineral most often forms earthy, dusty, or powdery coatings and crusts. Aggregates consisting of microscopic, poorly formed lath-like or tabular crystals are very rarely observed.
Geological environment
## Genesis Yttrotungstite-(Nd) is a secondary mineral. It forms in the oxidation (weathering) zones of tungsten ore deposits, especially within greisens and granitic pegmatites. It is formed as a result of hydrothermal alteration of primary tungstates, such as scheelite or wolframite, in an environment rich in rare earth elements. ## Mineral Associations It most often co-occurs with primary ore minerals, such as scheelite, wolframite, and ferberite, as well as with other secondary minerals, e.g., antoinite. ## Localities The most important and classic occurrence (type locality) of yttrotungstite-(Nd) is the Kramat Pulai mine in the Kinta district, Perak state, Malaysia. This is practically the only known place in the world from which well-identified specimens of this mineral originate.
Rarity
Extremely rare
Collector aspects
## Quality Criteria The quality of specimens of this mineral is assessed primarily based on the richness and extent of the coating on the rock matrix. Samples showing (under high magnification) microcrystal aggregates, rather than just dusty coatings, are more highly valued. Well-documented provenance from the type locality is also of great importance. ## Popular Localities The only significant locality for collectors is the Kramat Pulai mine in Malaysia, from which the best and type specimens of this mineral originate.
Care and storage
## Cleaning Yttrotungstite-(Nd) specimens are extremely delicate and soft. They should be cleaned with the utmost care, preferably using only compressed air to remove dust. Brushes, water, or any chemical agents should not be used. ## What to Avoid Any physical contact and friction, which can irreversibly damage the fragile coatings, should be avoided. The mineral is sensitive to acids and other chemicals. Ultrasonic cleaners should not be used. It should be protected from moisture and sudden temperature changes. ## Storage It is recommended to store specimens only in closed, padded "micromount" boxes, away from harder minerals that could damage them. Display should be in closed showcases, protecting against dust and mechanical damage.