Ungavaite

Chemical formula: Pd<sub>4</sub>Sb<sub>3</sub>

Ungavaite is an extremely rare palladium antimonide, forming microscopic, metallic grains in ultramafic rocks.

## Characteristics Ungavaite is a palladium antimonide belonging to the platinum-group minerals (PGM). It occurs as extremely small, anhedral (irregularly shaped) grains, usually not exceeding 100 micrometers in size. It is observed exclusively as inclusions within other minerals, most commonly in isomertieite. Due to its microscopic size, it does not form macroscopic specimens, and its visual characteristics can only be studied under high magnification, where it reveals its metallic nature. ## Physical Properties As an opaque mineral with a metallic luster, ungavaite is too small and rare for standard physical properties such as hardness, density, fracture, or cleavage to be measured. These values remain unmeasurable. In reflected light (under a ore microscope), its color is described as creamy white. ## History and Name The mineral's name comes from the Ungava Peninsula in the Nord-du-Québec administrative region of Canada, where its type locality, the Mesamax deposit, is located. It was formally described and approved as a new mineral species by the International Mineralogical Association (IMA) in 1982. The discovery was made by T.T. Chen, J.T. Szymański, and L.J. Cabri. ## Applications Ungavaite has no industrial or commercial applications. Its significance is purely scientific, serving as an indicator of geochemical processes leading to the concentration of platinum-group elements in specific types of deposits.

Properties

Luster
Metallic
Transparency
Opaque
Crystal system
Hexagonal

Diagnostic features

## Identification Identification of ungavaite is impossible without advanced laboratory equipment. It requires analysis under an ore microscope in reflected light, and final confirmation is obtained using an electron microprobe (EDS/WDS) or X-ray diffraction (XRD), which allow for the determination of its precise chemical composition (Pd₄Sb₃). ## Distinguishing from similar minerals Under the microscope, it can be confused with other platinum-group minerals (PGM) of similar creamy or white color in reflected light, such as genkinite, mertieite-II, or stibiopalladinite. Definitive differentiation is only possible based on quantitative chemical composition analysis. ## Crystal forms Ungavaite occurs exclusively as anhedral, irregular grains of microscopic size. No euhedral, well-formed crystals have been observed.

Geological environment

## Genesis Ungavaite crystallizes in the late stages of magmatic processes within ultramafic rocks, such as peridotites and dunites. Its formation is associated with the hydrothermal redistribution of platinum-group elements in serpentinized rocks, often in association with chromitite ores. ## Mineral associations This mineral most commonly occurs as inclusions in isomertieite. It also co-occurs with other platinum-group minerals, such as genkinite, mertieite-II, stibiopalladinite, as well as with chromite, pentlandite, chalcopyrite, and serpentine-group minerals. ## Localities The only confirmed and described locality of ungavaite worldwide is its type locality: the Mesamax nickel and copper deposit, located on the Ungava Peninsula in Quebec, Canada.

Rarity

Extremely rare

For collectors

## Quality criteria The quality of a ungavaite specimen is assessed solely in a scientific context. The most valuable are professionally prepared microscopic slides (sections) in which ungavaite grains are clearly visible, well-defined, and occur in association with other rare platinum-group minerals. Grain size, although always microscopic, is important – larger inclusions are more desirable for research purposes.

Care and storage

## Cleaning Specimens containing ungavaite (typically polished rock samples or thin sections) should only be cleaned with a dry, soft microfiber cloth to remove dust. Do not use water or any chemical agents. ## What to avoid Avoid contact with chemicals, acids, and ultrasonic cleaners, which could damage both the microscopic ungavaite grains and the surrounding minerals. Protect samples from scratching. ## Storage Ungavaite samples, most often in the form of professional thin sections or polished sections, should be stored in specialized microscope slide boxes, protecting them from dust and mechanical damage.

Sources

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