Michenerite

Chemical formula: Pd<sup>3+</sup>(BiTe)<sup>3-</sup>

Michenerite is a rare palladium tellurobismuthide, forming tiny, metallic inclusions in nickel and copper ores.

## Characteristics Michenerite is a rare sulfide group mineral, specifically a palladium tellurobismuthide. It typically occurs as very small, rounded or irregular grains, rarely exceeding 0.1 mm in diameter. Most often, it forms inclusions within other ore minerals. It is opaque and has a metallic luster, with a color on fresh surfaces ranging from tin-white to silvery-white, often with a pinkish tint. Over time, it may tarnish and develop a dull coating. ## Physical Properties This mineral is characterized by a Mohs hardness of 2.5, indicating it is relatively soft. Its density is high, approximately 10 g/cm³. It exhibits a distinct metallic luster. It is brittle and has an uneven fracture. ## Colors and Varieties Michenerite is an idiochromatic mineral, meaning its chemical composition determines its color. It is tin-white to silvery-white, sometimes with a pinkish or yellowish tint. No distinct color varieties or commercial names are recognized for it. ## History and Name The mineral was first described in 1958 by J.E. Hawley and L.G. Berry. The name honors Canadian geologist Charles Edward Michener (1907-2004), who first discovered this mineral in the Frood Mine in the Sudbury region, Canada. This location is recognized as the type locality for michenerite. ## Uses Due to its rarity and occurrence as microscopic grains, michenerite has no direct industrial application. However, it constitutes a minor source of palladium, which is recovered during the processing of rich nickel-copper ores in which it co-occurs.

Properties

Mohs hardness
2.5
Luster
Metallic
Streak
Black
Density
10
Cleavage
None
Fracture
Uneven
Transparency
Opaque
Crystal system
Cubic

Diagnostic features

## Identification Identifying michenerite without specialized equipment is practically impossible due to the microscopic size of its grains. In polished sections under a reflected light microscope, it can be recognized by its tin-white color with a pinkish tint, high reflectivity, and isotropism. Final confirmation requires advanced methods, such as electron microprobe analysis (EDS/WDS). ## Distinguishing from Similar Minerals It can be confused with other platinum-group minerals (PGMs), such as sperrylite, kotulskite, or merenskyite, which often co-occur with it and have a similar appearance in polished sections. They differ subtly in tint, hardness, and most importantly, chemical composition, which is crucial for their differentiation. ## Crystal Forms Michenerite crystallizes in the isometric system. It rarely forms poorly developed, small cubic crystals. It typically occurs as irregular, rounded grains and anhedral (xenomorphic) aggregates.

Geological environment

## Genesis Michenerite is a mineral of magmatic origin. It forms through the crystallization from residual, platinum-group element-rich, sulfide and telluride silicate-sulfide melts. It is a typical component of magmatic nickel, copper, and platinum-group element deposits associated with intrusions of mafic and ultramafic rocks, such as norites and pyroxenites. ## Mineral Associations It most commonly co-occurs with other ore minerals, such as chalcopyrite, pentlandite, pyrrhotite, as well as with other platinum-group minerals, e.g., sperrylite, moncheite, merenskyite, kotulskite, and native gold. ## Localities The most important michenerite localities worldwide are associated with large magmatic complexes. Key localities include the Sudbury region in Ontario (Canada), the Bushveld Complex in South Africa, deposits in the Norilsk region in Siberia (Russia), and the Stillwater Complex in Montana (USA).

Rarity

Very rare

For collectors

## Quality Criteria Michenerite specimens are not typically traded by collectors due to their microscopic nature. Polished ore sections in which michenerite has been identified and is visible under a microscope hold scientific and collector value. In such cases, the value is determined by the richness of the mineral paragenesis (presence of other rare PGM minerals) and its origin from a classic, well-documented locality. ## Popular Localities From a scientific and collector's perspective, specimens from the type locality – the Frood Mine in Sudbury (Canada) – are most highly prized, as are those from the Bushveld Complex (South Africa) and Norilsk (Russia), which have yielded the best-formed and most studied examples of this mineral.

Care and storage

## Cleaning Specimens with visible michenerite, most often in the form of polished sections, should be cleaned only very gently, using a soft, dry microfiber cloth to remove dust. Any contact with water and chemical agents should be avoided. ## What to Avoid The mineral is sensitive to acids and other chemicals. Moisture should be avoided, as it can accelerate the oxidation and tarnishing process of the surface. It should not be heated or exposed to sudden temperature changes. ## Storage Michenerite samples, especially polished sections, are best stored in closed, dry containers or display cases, away from moisture and contaminants. It is advisable to isolate them from other minerals that could scratch them.

Sources

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