Driekopite

Chemical formula: PtBi

Driekopite is a rare, metallic mineral from the platinum bismuthide group, occurring as small, hexagonal crystals and grains.

## Characteristics Driekopite is a rare mineral from the bismuthide group, composed of platinum and bismuth. It most commonly occurs as very small, hexagonal, tabular crystals, rarely exceeding 0.1 mm. It also forms irregular grains and inclusions within other ore minerals. Its appearance is typically metallic, with a color ranging from white to creamy white, often with a pinkish or yellowish tint. ## Physical Properties This mineral is characterized by a strong metallic luster. It is opaque. Due to the small size of its crystals, hardness and density have not been precisely measured, but only calculated based on its chemical composition and crystal structure. The calculated density is very high, approximately 14.88 g/cm³. ## Colors and Varieties The predominant color of driekopite is creamy white, often with a pinkish tint observed in reflected light. No varieties have been distinguished. ## History and Name The mineral's name comes from its discovery locality – the Driekop farm in South Africa. It was first described and approved as a new mineral by the International Mineralogical Association (IMA) in 1993. The discovery was made by a group of mineralogists, including C.J. Stanley, who was the lead author of the publication describing the mineral.

Properties

Luster
Metallic
Streak
Black
Density
12.91
Cleavage
None
Fracture
Uneven
Transparency
Opaque
Crystal system
Hexagonal

Diagnostic features

## Identification Identification of driekopite is impossible without specialized equipment. It requires analysis under a reflected light ore microscope, where it exhibits a characteristic creamy white color with a pinkish tint and strong anisotropy. Final confirmation is achieved through chemical composition analysis using methods such as electron microprobe (EDS/WDS). ## Distinguishing from Similar Minerals It can be confused with other platinum-group minerals (PGM) such as insizwaite (PtBi₂) or stumpflite (Pt(Sb,Bi)). They differ in the proportions of platinum to bismuth and antimony, which can only be determined by chemical analysis. In reflected light, insizwaite is more grayish-white compared to the creamy driekopite. ## Crystal Forms It forms very small, hexagonal, tabular crystals. Most commonly, it occurs as irregular grains and aggregates intergrown with other minerals.

Geological environment

## Genesis This is a magmatic mineral, associated with layered ultramafic and mafic intrusions. It forms in the late stages of crystallization of sulfide magma, rich in platinum-group elements (PGE). ## Mineral Associations It most commonly co-occurs with other platinum-group minerals such as braggite, cooperite, laurite, as well as with chalcopyrite, pentlandite, pyrrhotite, insizwaite, and stumpflite. ## Localities The most important and type locality is the Bushveld Igneous Complex in South Africa, specifically the deposits on the Driekop farm. It has also been reported in the Duluth Complex in Minnesota (USA) and in the Oktyabrskoye nickel deposit in Siberia (Russia).

Rarity

Very rare

For collectors

## Quality Criteria The quality of driekopite specimens is not assessed in the traditional way, as this mineral occurs exclusively as microscopic inclusions. The scientific and collector's value of a specimen depends on the richness of the mineral association (presence of other rare platinum-group minerals) and on the confirmation of its identity through analysis. Specimens from the type locality (Driekop) are most valued in scientific collections.

Care and storage

## Cleaning Driekopite specimens, due to their microscopic size and occurrence as inclusions, practically do not require cleaning. If necessary, only compressed air should be used to remove dust. ## What to Avoid Avoid contact with chemicals, acids, and cleaning agents that may react with sulfides and other associated minerals. Specimens should not be subjected to ultrasonic cleaning. ## Storage Specimens should be stored under stable conditions, in sealed boxes or display cases, to protect them from dust and mechanical damage. Due to the microscopic nature of the mineral, specialized micromount boxes are the best form of storage.

External references

Sources

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