Norilskite

Chemical formula: (Pd,Ag)<sub>₇</sub>Pb<sub>₄</sub>

Norilskite is a discredited name for a material, originally described as an alloy of palladium, silver, and lead from the Norilsk region, which was later found to be a mixture of minerals.

## Characteristics Norilskite is a name that was discredited in 2022 by the International Mineralogical Association (IMA). It was originally described as a rare mineral belonging to the native metals and alloys group. This material occurs as very small, irregular grains with a metallic luster, dispersed in sulfide ores. It is opaque, and its color was described as steel-gray with a yellowish tint. Studies have shown that the material considered norilskite is actually a mechanical mixture of at least two other minerals, including zvyagintsevite (Pd₃Pb). Consequently, norilskite is not recognized as a distinct, independent mineral species. ## Physical Properties Due to norilskite being a mixture, its physical properties have not been unambiguously and reliably determined. It is characterized by a metallic luster and is completely opaque. Other data, such as hardness or density, are not provided for the discredited material. ## Colors and Varieties The described material has a steel-gray color, often with a distinct yellowish or creamy tint. No varieties are distinguished, as it is not a homogeneous mineral. ## History and Name The name "norilskite" comes from its first discovery location – the copper-nickel deposits in the Norilsk region on the Taimyr Peninsula in Russia. The material was first described in 1997. In 2022, based on IMA proposal 22-C, the name was officially discredited when re-examination showed it to be a polymineralic mixture, not a single crystalline phase.

Properties

Luster: Metallic
Transparency: Opaque

Diagnostic features

## Identification Identification of the material originally described as norilskite is impossible without advanced laboratory techniques. Recognition requires chemical analysis using an electron microprobe (EDS/WDS) to determine its composition and demonstrate that it is a mixture of different mineral phases. Visually, it is indistinguishable from many other associated ore minerals. ## Distinguishing from Similar Minerals Under a microscope (in reflected light), it resembles many other platinum-group minerals and native metals, such as zvyagintsevite, polarite, other palladium-lead alloys, and silver-bearing varieties of gold. Definitive differentiation is possible only based on chemical composition. ## Crystal Forms It does not form crystals. It occurs exclusively as fine, irregular grains, aggregates, or thin veinlets, typically micrometers in size, most often at the grain boundaries of other minerals, mainly sulfides.

Geological environment

## Genesis Norilskite is associated with magmatic copper-nickel sulfide deposits, which formed as a result of basaltic magma crystallization within large mafic and ultramafic intrusions. Platinum-group minerals (PGM) crystallize in the late stages of this process, often as the last phases filling spaces between previously crystallized sulfides. ## Mineral Associations This material co-occurs with major copper and nickel ore sulfides, such as chalcopyrite, pentlandite, cubanite, and troilite. It is also accompanied by numerous other rare platinum-group minerals, including zvyagintsevite (of which it is a component), polarite, maslovite, as well as native silver and gold. ## Localities The only confirmed occurrence of the material described as norilskite is the Talnakh and Oktyabrskoye deposits in the Norilsk region, Siberia, Russia. This is the type locality for this discredited mineral.

Rarity

Extremely rare

For collectors

## Quality Criteria Norilskite is not a collector's mineral. It has been discredited as a mineral species and occurs only as microscopic inclusions in ores, which have no aesthetic or market value for collectors. Interest in it is limited solely to scientific research. ## Market Prices There is no market for this material. It is not traded commercially. ## Popular Localities The only known locality (Norilsk, Russia) is of scientific, not collecting, significance.

Care and storage

## Cleaning The issue of cleaning has no practical application. Norilskite is a discredited mineral occurring only as microscopic grains within solid rock (ore) and does not form collectible specimens that would require care. ## What to Avoid Since this material is studied exclusively under laboratory conditions in the form of polished sections, there are no recommendations regarding avoiding specific factors in collecting conditions. ## Storage Rock specimens containing microscopic inclusions of the former "norilskite" should be stored under stable conditions, typical for scientific and systematic collections – in a dry place, away from chemical contaminants.

Sources

IMA Mineral List (CNMNC)