Niggliite

Chemical formula: PtSn

Niggliite is a very rare mineral from the platinum-tin alloy group, occurring as microscopic, metallic inclusions in other minerals.

## Characteristics Niggliite is an extremely rare mineral, a natural alloy of platinum and tin. It usually forms only microscopic, elongated or irregular inclusions and lamellae within sulfides or other platinum group minerals. Due to its size, its visual features are difficult to observe without specialized equipment. Under a microscope in reflected light, it has a creamy-white color with a pinkish hue. ## Physical Properties As an opaque mineral with a metallic luster, it is characterized by high density, typical for platinum group metal alloys. It is a malleable and ductile mineral. Its hardness on the Mohs scale is relatively high, at 4. ## History and Name The mineral was first described in 1937 by D.L. Scholtz. The name niggliite was given in honor of Paul Niggli (1888–1953), a Swiss crystallographer and petrologist from the University of Zurich, for his contributions to the study of ore deposits.

Properties

Mohs hardness
4
Luster
Metallic
Streak
Black
Density
13.19
Cleavage
None
Fracture
Uneven
Transparency
Opaque
Crystal system
Hexagonal

Diagnostic features

## Identification Identification of niggliite is possible only through advanced laboratory techniques, such as ore microscopy (reflected light analysis) and chemical analysis using an electron microprobe (EDS/WDS). Its characteristic features include a creamy-white color with a pinkish hue and strong anisotropy in polarized light. ## Distinguishing from Similar Minerals It can be confused with other platinum-tin minerals, such as atokite (Pd,Pt)₃Sn or rustenburgite (Pt,Pd)₃Sn. Final differentiation requires precise chemical composition analysis, as all these minerals form microscopic, metallic grains with a similar appearance. ## Crystal Forms Niggliite crystallizes in the hexagonal system. It most often occurs as anhedral (irregular) grains, lamellae, or elongated inclusions, with sizes not exceeding several hundred micrometers.

Geological environment

## Genesis Niggliite is a mineral of magmatic origin. It forms in ultramafic and mafic layered intrusions, where it crystallizes from residual, platinum- and tin-rich sulfide melts. It is one of the late minerals to crystallize during the magma differentiation process. ## Mineral Associations It most commonly co-occurs with other platinum group minerals (PGM), such as braggite, cooperite, rustenburgite, and atokite. It is also accompanied by base metal sulfides, mainly pentlandite, pyrite, and pyrrhotite, as well as minerals such as chalcopyrite, cubanite, and magnetite. ## Localities The most important localities worldwide, from which the best-studied specimens originate, are the platinum group element deposits in the Bushveld Igneous Complex in South Africa (especially in the Merensky Reef), the Sudbury Complex in Canada, and the Dovyren intrusion in Russia, Siberia.

Rarity

Very rare

For collectors

## Quality Criteria The collector's value of niggliite is almost exclusively scientific. Since this mineral occurs as microscopic grains, it does not form visually attractive specimens for the typical collector. The most valuable are rock samples (polished sections) with well-documented presence of niggliite, confirmed by analyses, originating from known type localities such as Bushveld.

Care and storage

## Cleaning Specimens containing niggliite, due to their microscopic nature and occurrence as inclusions, practically do not require cleaning and should not be subjected to any mechanical or chemical treatments. ## What to Avoid Avoid contact with strong acids, which could damage both niggliite and the surrounding minerals (matrix). There are no specific recommendations regarding light or temperature, but extreme conditions should generally be avoided. ## Storage Store in stable room conditions, in a closed display box, to protect the specimen from dust and mechanical damage. Due to its rarity and scientific value, each specimen should be carefully labeled with its locality.

Sources

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