Nielsenite

Chemical formula: PdCu₃

Nielsenite is a very rare, naturally occurring palladium-copper alloy, forming microscopic inclusions in igneous rocks.

## Characteristics Nielsenite is a natural alloy (intermetallic compound) of palladium and copper. It occurs as extremely small, anhedral (irregularly shaped) grains, typically ranging from 1 to 35 micrometers in size. It is observed as inclusions within other minerals, primarily bornite. Due to its microscopic size, its visual characteristics are difficult to assess without specialized equipment. In reflected light, it has a steel-gray color. ## Physical Properties Due to the microscopic size of its grains, many physical properties of nielsenite have not been thoroughly investigated. It is an opaque mineral with a black streak. Hardness and density have not been measured. ## Colors and Varieties This mineral is homogeneous and does not exhibit color variation. Its only known color is steel-gray. It does not form varieties. ## History and Name Nielsenite was approved as a new mineral by the International Mineralogical Association (IMA) in 2018. Its name honors Troels F.D. Nielsen (born 1948), a Danish geologist and petrologist, for his significant contributions to the study of the Skaergaard intrusion in Greenland, where this mineral was discovered. It was described by a team of researchers, including Chris J. Stanley. ## Uses Nielsenite has no industrial application due to its extreme rarity and microscopic size. It is solely of scientific interest and is an object of interest for specialized collectors of rare minerals.

Properties

Luster
Metallic
Streak
Black
Density
0
Cleavage
None
Fracture
None observed
Transparency
Opaque
Crystal system
Tetragonal

Diagnostic features

## Identification Identification of nielsenite is impossible without advanced laboratory techniques. It requires analysis in reflected light using a polarizing microscope and confirmation of chemical composition using an electron microprobe (EDS/WDS) or X-ray diffraction (XRD). ## Distinguishing from Similar Minerals Due to its occurrence as microscopic, steel-gray grains, it can be confused with many other opaque ore minerals, such as other platinum-group minerals (PGM) or sulfides. Definitive differentiation is only possible based on chemical analysis. ## Crystal Forms Nielsenite forms only very small, anhedral (irregularly shaped) grains, most often as inclusions in bornite. No euhedral (well-formed) crystals have been observed.

Geological environment

## Genesis Nielsenite forms in the late stages of magma crystallization within large, differentiated layered igneous intrusions. It crystallizes from residual, copper- and platinum-group element (PGE)-rich sulfide melts under conditions of low sulfur fugacity. ## Mineral Associations This mineral occurs in close association with bornite (as inclusions), chalcopyrite, digenite, chalcocite, skaergaardite (PdCu), and other as-yet unnamed Pd-Cu-Au-Sn phases. ## Localities The only confirmed occurrence of nielsenite in the world is its type locality – the Skaergaard intrusion, near Kangerlussuaq Fjord on the east coast of Greenland.

Rarity

Extremely rare

For collectors

## Quality Criteria The quality of a nielsenite specimen is assessed solely based on the quality of the host rock and the richness of the mineral association. Nielsenite itself is invisible to the naked eye. The most highly valued samples are those with analytically confirmed presence of the mineral, originating directly from the type locality and containing rich parageneses of other rare minerals. ## Popular Localities The only source of specimens is the Skaergaard intrusion in Greenland. Material from this locality is extremely difficult to obtain and is available almost exclusively within scientific institutions and among highly specialized collectors.

Care and storage

## Cleaning Specimens containing nielsenite, due to its microscopic nature and occurrence as inclusions in other minerals, do not require and should not be subjected to cleaning. Any attempt at mechanical or chemical cleaning may damage the delicate mineral grains or the host rock. ## What to Avoid Avoid all chemicals, ultrasonics, and sudden temperature changes. The host specimen containing nielsenite should be protected from mechanical damage and abrasion. ## Storage It is recommended to store specimens in stable conditions, in sealed "micromount" boxes, to protect them from dust and physical damage. A label with precise location and identification is crucial.

External references

Sources

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