Tulameenite

Chemical formula: Pt₂CuFe

Tulameenite is a rare alloy of platinum, iron, and copper, forming fine, metallic grains of a silvery-white color.

## Characteristics Tulameenite is a rare mineral from the native elements group, being a natural alloy of platinum, iron, and copper. It occurs as small, irregular grains or as rims around other platinum-group minerals. Typical specimens rarely exceed 1 mm in size. It is opaque and has a metallic luster, and its color on a fresh fracture is silvery-white, often with a pinkish hue. ## Physical Properties This mineral is characterized by significant hardness, ranging from 5 to 5.5 on the Mohs scale. It is a dense mineral, which is typical for platinum alloys. It exhibits no cleavage, and its fracture is hackly, meaning that upon impact, the surface becomes jagged and sharp. It is malleable and ductile. ## History and Name The name tulameenite comes from its discovery location along the Tulameen River in British Columbia, Canada. The mineral was first described in 1974 by Louis J. Cabri, J.H. Gilles Laflamme, and John M. Stewart. ## Uses Due to its extreme rarity and small crystal sizes, tulameenite has no industrial applications. It is solely an object of scientific interest and a collector's item for specialized micromineral collectors.

Properties

Mohs hardness: 5
Color: White
Luster: Metallic
Streak: Black
Density: 0
Cleavage: None
Fracture: Hackly
Transparency: Opaque
Crystal system: Tetragonal

Diagnostic features

## Identification Identifying tulameenite without specialized equipment is practically impossible. It requires chemical analysis (e.g., using an electron microprobe - EDS/WDS) to confirm its Pt₂CuFe composition. In polished sections under a reflected light microscope, it has a characteristic silvery-white color with a pinkish hue. ## Distinguishing from Similar Minerals It can be confused with other platinum-group minerals, such as tetraferroplatinum or native platinum. Differentiation relies solely on precise chemical composition analysis, as their physical properties and appearance are very similar. ## Crystal Forms Tulameenite forms irregular, anhedral (not exhibiting its own faces) grains, often with rounded shapes. Poorly developed, cubic forms are rarely observed. It usually occurs as granular aggregates or as inclusions in other minerals.

Geological environment

## Genesis Tulameenite crystallizes in ultramafic magmatic complexes, particularly in rocks such as dunites and pyroxenites, which are rich in chromite. It forms during magmatic processes as one of the minerals solidifying from a sulfide-platinum melt. ## Mineral Associations It most commonly co-occurs with other platinum-group minerals (PGM), such as native platinum, iridium, osmium, as well as with chromite, magnetite, and various copper, nickel, and iron sulfides. ## Localities The most important and classic locality, which is also the type locality, is the area around the Tulameen River in British Columbia, Canada. This mineral has also been identified in ultramafic complexes in the Urals (Russia), Ethiopia (Yubdo area), and several other places worldwide where platinum-group element deposits are associated with ultramafic rocks.

Rarity

Very rare

For collectors

## Quality Criteria The quality of a tulameenite specimen is primarily assessed based on the size and abundance of grains within the host rock. As it is a micromineral, even small but well-visible and analytically confirmed grains are considered valuable. Specimens from the type locality (Tulameen River) are most prized, especially those containing rich associations of other rare platinum-group elements. ## Popular Localities The only source of collector-grade specimens is the Tulameen River region in British Columbia, Canada. Specimens from other localities are usually only available in scientific institutions.

Care and storage

## Cleaning Tulameenite specimens, usually in the form of microscopic grains within the host rock, generally do not require cleaning. If necessary, compressed air can be used to remove dust. Avoid contact with water and chemicals. ## What to Avoid Avoid contact with acids and other aggressive chemicals that may react with the metals comprising the mineral. Although it is quite hard, it should be protected from scratching by harder minerals. ## Storage It is recommended to store specimens in stable, dry conditions, preferably in "micromount" boxes or display cases that protect them from dust and mechanical damage.

External references

https://www.mindat.org/min-4046.html